https://www.pisavisionlab.org Research centre dedicated to frontier, interdisciplinary research of human perception Wed, 24 Nov 2021 20:35:38 +0000 en-US hourly 1 https://wordpress.org/?v=6.4.13 https://www.pisavisionlab.org/2019/12/24/three-systems-for-visual-numerosity-a-single-case-study-neuropsychologia-136-107259/ Tue, 24 Dec 2019 14:10:39 +0000 https://www.pisavisionlab.org/?p=1440 Neuropsychologia, 136, 107259 Humans possess the remarkable capacity to assess the numerosity of a set of items over a wide range of conditions, from a handful of items to hundreds of them. Recent evidence is starting to show that judgments over such a large range is possible because of the presence of three mechanisms, each tailored to specific stimulation conditions. Previous evidence in favour of this theory comes from the fact that discrimination thresholds and estimation reaction times are not constants across numerosity levels. Likewise, attention is capable of dissociating the three mechanisms: when healthy adult observers are asked to perform concurrently a taxing task, the judgments of low numerosities (<4 dots) or of high numerosities is affected greatly, not so however for intermediate numerosities. Here we bring evidence from a neuropsychological perspective. To this end we measured perceptual performance in PA, a 41 year-old patient who suffers simultanagnosia after a hypoxic brain injury. PA showed a profound deficit in attentively tracking objects over space and time (multiple object tracking), even in very simple conditions where controls made no errors. PA also showed a massive deficit on sensory thresholds when comparing dot-arrays containing extremely low (3 dots) or extremely high (64, 128 dots) numerosities as well as in comparing dot-distances. Surprisingly, PA discrimination thresholds were relatively spared for intermediate numerosity (12 and 16 dots). Overall his deficit on the numerosity task results in a U-shape function across numerosity which, combined with the attentional deficit and the inability to judge dot-distances, confirms previously suggested three-systems for numerosity judgments. Anobile, G., Tomaiuolo, F., Campana, S., & Cicchini, G. M. https://www.pisavisionlab.org/2019/12/24/three-systems-for-visual-numerosity-a-single-case-study-neuropsychologia-136-107259/2019_anobile_thrresystemsfor/https://doi.org/10.1016/j.neuropsychologia.2019.107259 https://www.pisavisionlab.org/2020/05/24/prova-2020/ Sun, 24 May 2020 04:59:06 +0000 https://www.pisavisionlab.org/?p=2344 Journal of Vision 2020;20(3):3 In paradigms of visual search where the search feature (say color) can change from trial to trials, responses are faster for trials where the search color is repeated than when it changes. This is a clear example of “priming” of attention. Here we test whether the priming effects can be revealed by pupillometry, and also whether they are related to autistic-like personality traits, as measured by the Autism-Spectrum Quotient (AQ). We repeated Maljkovic and Nakayama's (1994) classic priming experiment, asking subjects to identify rapidly the shape of a singleton target defined by color. As expected, reaction times were faster when target color repeated, and the effect accumulated over several trials; but the magnitude of the effect did not correlate with AQ. Reaction times were also faster when target position was repeated, again independent of AQ. Presentation of stimuli caused the pupil to dilate, and the magnitude of dilation was greater for switched than repeated trials. This effect did not accumulate over trials, and did not correlate with the reaction times difference, suggesting that the two indexes measure independent aspects of the priming phenomenon. Importantly, the amplitude of pupil modulation correlated negatively with AQ, and was significant only for those participants with low AQ. The results confirm that pupillometry can track perceptual and attentional processes, and furnish useful information unobtainable from standard psychophysics, including interesting dependencies on personality traits. Pomè, A., Binda, P., Cicchini, G.M., Burr. D.C. (2020). https://www.pisavisionlab.org/2020/05/24/prova-2020/pupillometry-correlates-of-visual-priming-and-their-dependency-on-autistic-traits/https://doi.org/10.1167/jovi.20.3.3 https://www.pisavisionlab.org/2020/05/30/neuroplasticity-in-adult-human-visual-cortex-neuroscience-biobehavioral-reviews-volume-112-may-2020-pages-542-552/ Sat, 30 May 2020 13:47:26 +0000 https://www.pisavisionlab.org/?p=2386 Neuroscience & Biobehavioral Reviews, 112, 542–552 Between 1-5:100 people worldwide have never experienced normotypic vision due to a condition called amblyopia, and about 1:4000 suffer from inherited retinal dystrophies that progressively lead to blindness. While a wide range of technologies and therapies are being developed to restore vision, a fundamental question still remains unanswered: would the adult visual brain retain a sufficient plastic potential to learn how to ‘see’ after a prolonged period of abnormal visual experience? In this review we summarize studies showing that the visual brain of sighted adults retains a type of developmental plasticity, called homeostatic plasticity, and this property has been recently exploited successfully for adult amblyopia recovery. Next, we discuss how the brain circuits reorganize when blindness occurs and when visual stimulation is partially restored by means of a ‘bionic eye’ in late blind adults with Retinitis Pigmentosa. The primary visual cortex in these patients slowly became activated by the artificial visual stimulation, indicating that sight restoration therapies can rely on a considerable degree of spared plasticity in adulthood. Castaldi, E., Lunghi, C., & Morrone, M. C. https://www.pisavisionlab.org/2020/05/30/neuroplasticity-in-adult-human-visual-cortex-neuroscience-biobehavioral-reviews-volume-112-may-2020-pages-542-552/1-s2-0-s0149763419303288-main/https://doi.org/10.1016/j.neubiorev.2020.02.028 https://www.pisavisionlab.org/2020/05/30/mapping-numerical-perception-and-operations-in-relation-to-functional-and-anatomical-landmarks-of-human-parietal-cortex/ Sat, 30 May 2020 13:57:02 +0000 https://www.pisavisionlab.org/?p=2390 NeuroImage, 221, 117210 Human functional imaging has identified the middle part of the intraparietal sulcus (IPS) as an important brain substrate for different types of numerical tasks. This area is often equated with the macaque ventral intraparietal area (VIP) where neuronal selectivity for non-symbolic numerical stimuli (sets of items) is found. However, the low spatial resolution and whole-brain averaging analysis performed in most fMRI studies limit the extent to which an exact correspondence of activations in different numerical tasks with specific sub-regions of the IPS can be established. Here we acquired high-resolution 7T fMRI data in a group of human adults and related the activations in several numerical contrasts (implying different numerical stimuli and tasks) to anatomical and functional landmarks on the cortical surface. Our results reveal a functional heterogeneity within human intraparietal cortex where the retinotopic visual field maps in superior/medial parts of the IPS and superior parietal gyrus respond preferentially to the visual processing of concrete sets of items (over single Arabic numerals), whereas lateral/inferior parts of the IPS are predominantly recruited during numerical operations such as calculation and quantitative comparison. Since calculation and comparison-related activity fell mainly outside the retinotopic visual field maps considered the human functional equivalent of the monkey VIP/LIP complex, the areas most activated during such numerical operations in humans are likely different from VIP. Castaldi, E., Vignaud, A., & Eger, E. https://www.pisavisionlab.org/2020/05/30/mapping-numerical-perception-and-operations-in-relation-to-functional-and-anatomical-landmarks-of-human-parietal-cortex/1-s2-0-s1053811920306960-main/https://doi.org/10.1016/j.neuroimage.2020.117210 https://www.pisavisionlab.org/2020/05/31/motor-adaptation-distorts-visual-space/ Sun, 31 May 2020 04:29:47 +0000 https://www.pisavisionlab.org/?p=2394 Vision Research, 171, 31-35. It has been suggested that the human visual system exploits an adaptable metric to implement a precise but plastic spatial representation. Indeed, adapting to a dense dot-texture reduces the apparent separation of subsequently presented dots pairs. Whether this metric is purely visual or shared between senses is still unknown. Here we present a new cross-modal after-effect revealing that the metric with which the visual system computes the relative spatial position of objects is shared with the motor system. A few seconds of mid-air self-produced tapping movements (adaptation) yielded a robust compression of the apparent separation of dot pairs subsequently displayed around the tapping region. This visuo-motor spatial metric could reflect an efficient functional architecture to program and execute actions aimed at efficient interaction with the objects in the environment. Petrizzo, I., Anobile, G., & Arrighi, R. https://www.pisavisionlab.org/2020/05/31/motor-adaptation-distorts-visual-space/1-s2-0-s0042698920300675-main/https://doi.org/10.1016/j.visres.2020.04.007 https://www.pisavisionlab.org/2020/05/31/math-anxiety-mediates-the-link-between-number-sense-and-math-achievements-in-high-math-anxiety-young-adults/ Sun, 31 May 2020 04:33:28 +0000 https://www.pisavisionlab.org/?p=2396 Frontiers in Psychology, 11, 1095 In the past few years, many studies have suggested that subjects with high sensory precision in the processing of non-symbolic numerical quantities (approximate number system; ANS) also have higher math abilities. At the same time, there has been interest in another non-cognitive factor affecting mathematical learning: mathematical anxiety (MA). MA is defined as a debilitating emotional reaction to mathematics that interferes with the manipulation of numbers and the solving of mathematical problems. Few studies have been dedicated to uncovering the interplay between ANS and MA and those have provided conflicting evidence. Here we measured ANS precision (numerosity discrimination thresholds) in a cohort of university students with either a high (>75th percentile; n = 49) or low (<25th percentile; n = 39) score on the Abbreviate Math Anxiety Scale (AMAS). We also assessed math proficiency using a standardized test (MPP: Mathematics Prerequisites for Psychometrics), visuo-spatial attention capacity by means of a Multiple Objects Tracking task (MOT) and sensory precision for non-numerical quantities (disk size). Our results confirmed previous studies showing that math abilities and ANS precision correlate in subjects with high math anxiety. Neither precision in size-discrimination nor visuo-spatial attentional capacity were found to correlate with math capacities. Interestingly, within the group with high MA, our data also revealed a relationship between ANS precision and MA, with MA playing a key role in mediating the correlation between ANS and math achievement. Taken together, our results suggest an interplay between extreme levels of MA and the sensory precision in the processing of non-symbolic numerosity. Maldonado Moscoso, P. A., Anobile, G., Primi, C., & Arrighi, R. https://www.pisavisionlab.org/2020/05/31/math-anxiety-mediates-the-link-between-number-sense-and-math-achievements-in-high-math-anxiety-young-adults/fpsyg-11-01095/https://doi.org/10.3389/fpsyg.2020.01095 https://www.pisavisionlab.org/2020/06/01/shaping-the-visual-system-cortical-and-subcortical-plasticity-in-the-intact-and-the-lesioned-brain-neuropsychologia/ Mon, 01 Jun 2020 14:22:13 +0000 https://www.pisavisionlab.org/?p=2527 Neuropsychologia, 142, 107464 Visual system is endowed with an incredibly complex organization composed of multiple visual pathway affording both hierarchical and parallel processing. Even if most of the visual information is conveyed by the retina to the lateral geniculate nucleus of the thalamus and then to primary visual cortex, a wealth of alternative subcortical pathways is present. This complex organization is experience dependent and retains plastic properties throughout the lifespan enabling the system with a continuous update of its functions in response to variable external needs. Changes can be induced by several factors including learning and experience but can also be promoted by the use non-invasive brain stimulation techniques. Furthermore, besides the astonishing ability of our visual system to spontaneously reorganize after injuries, we now know that the exposure to specific reha­ bilitative training can produce not only important functional modifications but also long-lasting changes within cortical and subcortical structures. Grasso, P. A., Gallina, J., & Bertini, C. https://doi.org/10.1016/j.neuropsychologia.2020.107464 https://www.pisavisionlab.org/2020/06/01/effects-of-different-transcranial-direct-current-stimulation-protocols-on-visuo-spatial-contextual-learning-formation-evidence-of-homeostatic-regulatory-mechanisms-scientific-reports-101/ Mon, 01 Jun 2020 14:23:58 +0000 https://www.pisavisionlab.org/?p=2529 Scientific Reports, 10(1), 4622 In the present study we tested the effects of different transcranial direct current stimulation (tDCS) protocols in the formation of visuo-spatial contextual learning (VSCL). The study comprised three experiments designed to evaluate tDCS-induced changes in VSCL measures collected during the execution of a visual search task widely used to examine statistical learning in the visuo-spatial domain. In Experiment 1, we probed for the effects of left-posterior parietal cortex (PPC) anodal-tDCS (AtDCS) at different timings (i.e. offline and online) and intensities (i.e. 3 mA and 1.5 mA). The protocol producing the more robust effect in Experiment 1 was used in Experiment 2 over the right-PPC, while in Experiment 3, cathodal-tDCS (CtDCS) was applied over the left-PPC only at a high intensity (i.e. 3 mA) but varying timing of application (offline and online). Results revealed that high intensity offline AtDCS reduced VSCL regardless of the stimulation side (Experiment 1 and 2), while no significant behavioral changes were produced by both online AtDCS protocols (Experiment 1) and offline/online CtDCS (Experiment 3). The reduced VSCL could result from homeostatic regulatory mechanisms hindering normal task-related neuroplastic phenomena. Grasso, P. A., Tonolli, E., & Miniussi, C. https://www.pisavisionlab.org/2020/06/01/effects-of-different-transcranial-direct-current-stimulation-protocols-on-visuo-spatial-contextual-learning-formation-evidence-of-homeostatic-regulatory-mechanisms-scientific-reports-101/effects-of-different-transcranial-direct-current-stimulation-protocols-on-visuo-spatial-contextual-learning-formation-evidence-of-homeostatic-regulatory-mechanisms/https://www.nature.com/articles/s41598-020-61626-7 https://www.pisavisionlab.org/2020/06/01/alpha-oscillations-reveal-implicit-visual-processing-of-motion-in-hemianopia-cortex-122-81-96/ Mon, 01 Jun 2020 14:29:20 +0000 https://www.pisavisionlab.org/?p=2531 Cortex, 122, 81–96 After lesion or deafferentation of the primary visual cortex, hemianopic patients experience loss of conscious vision in their blind field. However, due to the spared colliculoextrastriate pathway, they might retain the ability to implicitly process motion stimuli through the activation of spared dorsal-extrastriate areas, despite the absence of awareness. To test this hypothesis, Electroencephalogram (EEG) was recorded from a group of hemianopic patients without blindsight (i.e., who performed at chance in different forcedchoice tasks), while motion stimuli, static stimuli or no stimuli (i.e., blank condition) were presented either in their intact or in their blind visual field. EEG analyses were performed in the time-frequency domain. The presentation of both motion and static stimuli in the intact field induced synchronization in the theta band and desynchronization both in the alpha and the beta band. In contrast, for stimuli presented in the blind field, significantly greater desynchronization in the alpha range was observed only after the presentation of motion stimuli, compared to the blank condition, over posterior parietal-occipital electrodes in the lesioned hemisphere, at a late time window (500e800 msec). No alpha desynchronization was elicited by static stimuli. These results show that hemianopic patients can process only visual signals relying on the activation of the dorsal pathway (i.e., motion stimuli) in the absence of awareness and suggest different patterns of electrophysiological activity for conscious and unconscious visual processing. Specifically, visual processing in the absence of awareness elicits an activity limited to the alpha range, most likely reflecting a “local” process, occurring within the extrastriate areas and not participating in inter-areal communication. This also suggests a response specificity in this frequency band for implicit visual processing. In contrast, visual awareness evokes changes in different frequency bands, suggesting a “global” process, accomplished by activity in a wide range of frequencies, probably within and across cortical areas. Grasso, P. A., Pietrelli, M., Zanon, M., Làdavas, E., & Bertini, C. https://doi.org/10.1016/j.cortex.2018.08.009 https://www.pisavisionlab.org/2020/06/29/vision-science-society-annual-meeting-on-line-event/ Mon, 29 Jun 2020 20:21:13 +0000 https://www.pisavisionlab.org/?p=2656 ["live talk"] Vision Science Society annual meeting (on-line event) 19/06/2020 24/06/2020 Paola Binda, Miriam Acquafredda, Claudia Lunghi https://www.pisavisionlab.org/2020/06/29/voluntary-action-rhythmically-modulates-7t-bold-visual-responses-in-primary-visual-cortex/ Mon, 29 Jun 2020 20:25:46 +0000 https://www.pisavisionlab.org/?p=2659 ["digital poster"] ISMRM 2020 Morrone Maria Concetta, Benedetto Alessandro, Costagli Mauro, Tosetti Michela, Binda Paola

Paris France

48.856614 2.3522219 14 ChIJD7fiBh9u5kcRYJSMaMOCCwQ Parigi Île-de-France IDF Francia FR https://www.pisavisionlab.org/2020/06/30/the-common-rhythm-of-action-and-perception-journal-of-cognitive-neuroscience-2/ Tue, 30 Jun 2020 18:41:17 +0000 https://www.pisavisionlab.org/?p=2666 Journal of Cognitive Neuroscience, 32(2), 187–200. Research in the last decade has undermined the idea of perception as a continuous process, providing strong empirical support for its rhythmic modulation. More recently, it has been revealed that the ongoing motor processes influence the rhythmic sampling of sensory information. In this review, we will focus on a growing body of evidence suggesting that oscillation-based mechanisms may structure the dynamic interplay between the motor and sensory system and provide a unified temporal frame for their effective coordination. We will describe neurophysiological data, primarily collected in animals, showing phase-locking of neuronal oscillations to the onset of (eye) movements. These data are complemented by novel evidence in humans, which demonstrate the behavioral relevance of these oscillatory modulations and their domain-general nature. Finally, we will discuss the possible implications of these modulations for action–perception coupling mechanisms. Benedetto, A., Morrone, M. C., & Tomassini, A. https://www.pisavisionlab.org/2020/06/30/the-common-rhythm-of-action-and-perception-journal-of-cognitive-neuroscience-2/2020-jcogneurosci/https://doi.org/10.1162/jocn_a_01436 https://www.pisavisionlab.org/2020/07/13/motor-adaptation-distorts-space/ Mon, 13 Jul 2020 09:25:38 +0000 https://www.pisavisionlab.org/?p=2804 ["poster"] European Workshop on Cognitive Neuropsychology EWCN 2020, Bressanone Introduction : It has been recently demonstrated that adapting to self-produced motion induces a compression of both perceived numerosity and duration. These results suggest the existence of visuomotor mechanisms that encode numerosity and duration of external as well as internal events. However, according to the ATOM theory, the perception of time and numerosity might also be linked to the processing of spatial information, with all these dimensions tapping a common neural mechanism. To test this hypothesis, we assessed whether motor adaptation also affects the perception of visual stimuli distance, and compared these results to visual adaptation (to high density texture), which is known to distort spatial separation.<br>Methods : We measured the effects of visual and motor adaptation on the perceived separation of dots. Participants were presented with two vertically aligned dot pairs, separated by about 4° (with random variation of 0.3°), and centered 9.55° either side of fixation. They indicated in 2AFC which pair appeared separated by the shorter distance. In the adaptation trials, the stimuli were preceded by a 5-sec presentation of dense visual texture (visual adaptation), or by the participant rapidly tapping in mid-air with their dominant hand (motor adaptation) for 6 secs (in separate sessions). The effect of adaptation was measured by the shift of the point of subjective equality (PSE) before and after adaptation.<br>Results : Our data show that adaptation to self-produced fast hand movement induces a significant compression of the perceived spatial separation of the stimuli presented around the tapping location. The magnitude of motor adaptation aftereffects was robust, around 3%, a little smaller than that achieved by visual adaptation (around 10%). Importantly, distortions of perceived distance occurred only for stimuli presented around the adapted location, showing that the effect of both motor and visual adaptation is spatially selective.<br>Discussion : We report here that the estimated distance of two visual stimuli was compressed by repetitive motor action, similarly to adaptation to dense visual patterns. The spatial selectivity of the aftereffects suggests they do not derive from a decisional bias, but points to spatially selective mechanisms combining motor and visual information. To conclude, our results extend previous reports about the interaction of the perceptual and motor systems in the processing of time and numerosity to the processing of visual space. This is in line with the core idea of the ATOM theory of a shared representation for time, numerosity and space that optimizes the combination of perceptual information with motor planning and execution.<br>References : Walsh V Trends in cogn sci 7.11 (2003) 483-488 Hisakata R et al Curr Bio 26.14 (2016) 1911-1915 Anobile G et al J of Exp Psychology: General in press<br>Keywords : Perception & imagery; normal population; group study; adults; not relevant; behavioural, behavioural. 26/01/2020 31/01/2020 Petrizzo, I., Anobile, G., Burr, D. C., & Arrighi, R.

Bressanone

46.7177048 11.6572436 14 ChIJzQkqEmkFeEcR_Zac_Ls-KC8 Bressanone Trentino-Alto Adige BZ 39042 Italia IT https://www.pisavisionlab.org/2020/07/13/numerosity-adaptation-changes-in-sensory-processes-or-in-decision-making-2/ Mon, 13 Jul 2020 09:27:22 +0000 https://www.pisavisionlab.org/?p=2807 ["poster"] European Workshop on Cognitive Neuropsychology EWCN 2020 Bressanone Introduction : Humans and other animals can make rapid but approximate estimates of the numerosity of items in a scene, an ability often termed the number sense. Numerosity perception, like other senses, is susceptible to sensory adaptation: after an exposure to a patch containing many dots, subjects underestimate the numerosity of a second stimulus subsequently presented in the adapted region, with the opposite occurring for adaptation to small numerosities. Do these aftereffects arise from a change in the processing of sensory signals, or from a shift of criteria at the decisional stage? Methods : We addressed this question by investigating the effects of numerosity visual adaptation and motor adaptation in a 2AFC discrimination task on apparent numerosity (measured as point of subjective equality, or PSE), as well as on subjective confidence and reaction time. Results : Our results show that shifts in perceived numerosity after visual and motor adaptation are mirrored by shifts in both confidence and reaction time, with the maximum uncertainty and longest response time occurring at the point of subjective equality rather than at the point of physical equality. Discussion : Taken together these results are consistent with the hypothesis that numerosity adaptation aftereffects are perceptual in nature and not related to decisional processes. References : Morgan M. et al. Atten Percept Psychophys. (2012) 74(1):185-93. Abobile et al. eLife (2016) 5: e16161. Keywords : Numerical Cognition; normal population; group study; adults; not relevant; behavioural, behavioural. 26/01/2020 31/01/2020 Arrighi, R., Maldonado, P., Cicchini, G.M., Burr, D.

Bressanone

46.7177048 11.6572436 14 ChIJzQkqEmkFeEcR_Zac_Ls-KC8 Bressanone Trentino-Alto Adige BZ 39042 Italia IT https://www.pisavisionlab.org/2020/07/13/three-systems-for-visual-numerosity-a-single-case-study/ Mon, 13 Jul 2020 09:29:05 +0000 https://www.pisavisionlab.org/?p=2810 ["poster"] European Workshop on Cognitive Neuropsychology EWCN 2020 Introduction: Humans possess the capacity to assess the numerosity of a set of items over a wide range of conditions, from a handful to hundreds of items. Recent evidence shows that judgments over such a large range is facilitated by three separate mechanisms, each tuned to a specific range [1]. One means of dissociating the three mechanisms is attention: when healthy adults are asked to perform concurrently a taxing task, the judgments of low numerosities (<4 dots) and also high numerosities is affected greatly, but not intermediate numerosities [2]. Here we bring evidence from a neuropsychological perspective. We measured numerosity performance in PA, a 41-year-old patient who suffers a profound visual attentional deficit after a hypoxic brain injury. Methods: We psychophysically measured numerosity discrimination, object-distance discrimination and visual attention performance in healthy adults and in a 41-year-old patient (PA) who suffered from hypoxic insult due to a heart attack. Discrimination of numerosity and object-distance were indexed by thresholds measured in two alternative forced choice. Visual attention was measured by percent of correct choices on a multiple object tracking task. Statistical differences between accuracy rates and chance level in the Multiple Object Tracking were computed by binomial tests. Statistical differences on accuracy levels between PA and controls were calculated by Chisquare tests. The statistical differences on discrimination thresholds (WF) were calculated by a bootstrap technique. Results: PA showed a profound deficit in attentive tracking of objects over space and time (multiple object tracking), even in very simple conditions where typical participants made no errors. PA also showed a massive deficit on sensory thresholds when comparing dot-arrays containing extremely low (3 dots) or extremely high (64, 128 dots) numerosities as well as in comparing objects-distances. Surprisingly, PA discrimination thresholds were relatively spared for intermediate numerosities (12 and 16 dots). Discussion: We recently suggested that numerosity is processed by three mechanisms: 1) an attentional subitizing system working for low numerosities, up to about four; 2) a relatively attentional free estimation system, working at intermediate numerosities; and 3) an attentiondependent texture-density system coming into play for extremely high numerosities1-2. Here we tested the model from a neuropsychological perspective by measuring numerosity performance in a single patient (PA) suffering profound attentional losses after a hypoxic insult. Overall, PA deficit on the numerosity task is a U-shape function across numerosity levels which, combined with the attentional deficit, confirms the three-systems model for numerosity perception. References : 1. Anobile, G., et. al. Perception. (2016). 45, 5-31 2. Pomè, A., et. al. Atten Percept Psychophys. (2019) 81, 2604-2611 26/01/2020 31/01/2020 Giovanni Anobile, Francesco Tomaiuolo, Serena Campana, Guido Marci Cicchini https://www.pisavisionlab.org/2020/07/13/three-systems-for-visual-numerosity-a-single-case-study/1-s2-0-s002839321930301x-main-1/

Bressanone

46.7177048 11.6572436 14 ChIJzQkqEmkFeEcR_Zac_Ls-KC8 Bressanone Trentino-Alto Adige BZ 39042 Italia IT https://doi.org/10.1016/j.neuropsychologia.2019.107259 https://www.pisavisionlab.org/2020/07/13/adaptation-to-hand-tapping-affects-directly-sensory-processing-of-numerosity/ Mon, 13 Jul 2020 09:30:55 +0000 https://www.pisavisionlab.org/?p=2813 ["digital poster"] Vision Science Society annual meeting, 20th annual meeting on-line event Several studies have demonstrated that numerosity perception is susceptible to adaptation: after exposure to high numerosities, participants underestimate the numerosity of subsequently patterns, and over-estimate after adaptation to low numerosities. We have recently shown that motor routines such as hand-tapping also affect numerosity estimates, and that the motor adaptation is confined to the tapping region, pointing to shared mechanisms encoding the quantity of both internally generated actions and externally generated events. However, it has been suggested that adaptation studies may reflect response biases rather than alteration of sensory processing. To disentangle the two possibilities, we studied visual and motor adaptation on numerosity perception (determined by the point of subjective equality in a 2AFC discrimination task), while also measuring participant confidence and reaction-times. If adaptation occurs at the sensory level, peaks in reaction-times and troughs in confidence should shift with adaptation to follow the new PSE, where the stimuli are most difficult to discriminate (Gallagher et al., 2019). On the other hand, if they result from response biases when confidence is low, the confidence (and also reaction-time) curves should remain centered at the unadapted PSE after adaptation. We replicate previous studies showing that both sensory and motor adaptation robustly distort numerosity estimates by 23% and 14% respectively. Importantly, in both cases, the shifts in perceived numerosity were almost perfectly mirrored by shifts in confidence and reaction-times, with the maximum uncertainty and longest response-times occurring at the point of subjective equality rather than at the point of physical equality. Taken together our results suggest that both forms of numerosity adaptation do not arise by decisional processes but directly act on the sensory representation of numerosity Acknowledgements: This research was funded by EU Horizon 2020 – ERC Advanced “Spatio-temporal mechanisms of generative perception”, Grant number 832813 – GenPercept and by the Italian Ministry of Education, University, and Research under the PRIN2017 programme (Grant number 2017XBJN4F— ‘EnvironMag’ ) 19/06/2020 24/06/2020 Arrighi, R., Maldonado, P., Cicchini, G.M., Burr, D. https://www.pisavisionlab.org/2020/07/15/a-closer-look-at-the-timecourse-of-mind-wandering-pupillary-responses-and-behaviour/ Wed, 15 Jul 2020 08:36:03 +0000 https://www.pisavisionlab.org/?p=2873 PLOS ONE 15(4): e0226792 Mind wandering (MW) refers to the shift of attention away from a primary task and/or external environment towards thoughts unrelated to the task. Recent evidence has shown that pupillometry can be used as an objective marker of the onset and maintenance of externally-driven MW episodes. In the present study we aimed to further investigate pupillary changes associated with the onset and duration of self-reported MW episodes. We used a modified version of the joint behavioural-pupillometry paradigm we recently introduced. Participants were asked to perform a monotonous vigilance task which was intermixed with task-irrelevant cue-phrases (visually presented verbal cues); they were instructed to interrupt the task whenever a thought came to mind (self-caught method) and to indicate the trigger of their thought, if any. We found systematic pupil dilation after the presentation of verbal cues reported to have triggered MW, compared with other verbal cues presented during a supposedly on-task period (i.e., the period immediately following the resuming of the task after a self-caught interruption and MW report). These results confirm that pupil diameter is sensitive to the changes associated with the onset of MW and its unfolding over time. Moreover, by computing the latency between the trigger presentation and the task interruption (self-catch), we could also estimate the duration of MW episodes triggered by verbal cues. However, a high variability was found, implying very large inter-event variability, which could not be explained by any of the MW properties we acquired (including: temporal focus, specificity, emotional valence). Our behavioural and pupillometry findings stress the need for objective measures about the temporal unfolding of MW (while most studies focus on arbitrary time-window preceding self-reports of MW). Pelagatti C, Binda P, Vannucci M (2020) https://www.pisavisionlab.org/2020/07/15/a-closer-look-at-the-timecourse-of-mind-wandering-pupillary-responses-and-behaviour/a-closer-look-at-the-timecourse-of-mind-wandering-pupillary-responses-and-behaviour/https://doi.org/10.1371/journal.pone.0226792 https://www.pisavisionlab.org/2020/07/17/a-closer-look-at-the-timecourse-of-mind-wandering-pupillary-responses-and-behaviour-2/ Fri, 17 Jul 2020 07:58:45 +0000 https://www.pisavisionlab.org/?p=2901 PLOS ONE 15(4): e0226792 Pelagatti C, Binda P, Vannucci M (2020) https://doi.org/10.5281/zenodo.3673044 https://www.pisavisionlab.org/2020/07/20/using-psychophysical-performance-to-predict-short-term-ocular-dominance-plasticity-in-human-adults/ Mon, 20 Jul 2020 06:56:20 +0000 https://www.pisavisionlab.org/?p=3003 Journal of Vision July 2020, Vol.20, 6. Binocular rivalry has become an important index of visual performance, both to measure ocular dominance or its plasticity, and to index bistable perception. We investigated its interindividual variability across 50 normal adults and found that the duration of dominance phases in rivalry is linked with the duration of dominance phases in another bistable phenomenon (structure from motion). Surprisingly, it also correlates with the strength of center–surround interactions (indexed by the tilt illusion), suggesting a common mechanism supporting both competitive interactions: center–surround and rivalry. In a subset of 34 participants, we further investigated the variability of short-term ocular dominance plasticity, measured with binocular rivalry before and after 2 hours of monocular deprivation. We found that ocular dominance shifts in favor of the deprived eye and that a large portion of ocular dominance variability after deprivation can be predicted from the dynamics of binocular rivalry before deprivation. The single best predictor is the proportion of mixed percepts (phases without dominance of either eye) before deprivation, which is positively related to ocular dominance unbalance after deprivation. Another predictor is the duration of dominance phases, which interacts with mixed percepts to explain nearly 50% of variance in ocular dominance unbalance after deprivation. A similar predictive power is achieved by substituting binocular rivalry dominance phase durations with tilt illusion magnitude, or structure from motion phase durations. Thus, we speculate that ocular dominance plasticity is modulated by two types of signals, estimated from psychophysical performance before deprivation, namely, interocular inhibition (promoting binocular fusion, hence mixed percepts) and inhibition for perceptual competition (promoting longer dominance phases and stronger center–surround interactions). Cecilia Steinwurzel; Silvia Animali; Guido Marco Cicchini; Maria Concetta Morrone; Paola Binda https://www.pisavisionlab.org/2020/07/20/using-psychophysical-performance-to-predict-short-term-ocular-dominance-plasticity-in-human-adults/i0035-8711-663-1-07322/https://doi.org/10.1167/jov.20.7.6 https://www.pisavisionlab.org/2020/07/21/serial-dependence-in-perception-requires-conscious-awareness/ Tue, 21 Jul 2020 06:04:20 +0000 https://www.pisavisionlab.org/?p=3036 Current Biology 30, R237–R262, March 23, 2020 Current visual perception is systematically biased towards the immediate past, an effect known as serial dependence. A variety of basic visual features, including orientation, motion and numerosity, show serial dependence, but it remains unclear whether perceptual awareness is necessary. We address this question by combining serial dependence for orientation with binocular rivalry between orthogonal gratings. Fourteen participants viewed trial sequences which alternated between rivalrous presentations, with orthogonal gratings to each eye, and monocularly presented test gratings. Participants indicate the orientation of the stimuli – either the dominant percept in rivalry or the orientation of the test – by matching with a rotatable line. Half of the rivalry trials were selected (at random) for the “dominant” condition, half for the “supressed” condition. The subsequent test was presented to the appropriate eye (dominant or suppressed) at an orientation rotated ±10° from the chosen rivalrous stimulus. We found that orientation estimates were strongly biased towards the preceding trial (positive serial dependence), but only in the dominance condition, not in the suppression condition. These results were replicated with test gratings presented binocularly in a separate experiment. These results show that only if stimuli are consciously perceived will they act as a prior to bias subsequent perception, suggesting that construction of the prior occurs at a relatively high level. However, the results do not speak to the issue of the stage of analysis where the prior distorts incoming sensory information. Sujin Kim, David Burr, Guido Marco Cicchini, David Alais https://www.pisavisionlab.org/2020/07/21/serial-dependence-in-perception-requires-conscious-awareness/kimetal_currbio2020/https://doi.org/10.1016/j.cub.2020.02.008 https://www.pisavisionlab.org/2020/08/01/excessive-visual-crowding-effects-in-developmental-dyscalculia/ Sat, 01 Aug 2020 13:54:20 +0000 https://www.pisavisionlab.org/?p=2388 Journal of Vision, 20(8), 7–7 Visual crowding refers to the inability to identify objects when surrounded by other similar items. Crowding-like mechanisms are thought to play a key role in numerical perception by determining the sensory mechanisms through which ensembles are perceived. Enhanced visual crowding might hence prevent the normal development of a system involved in segregating and perceiving discrete numbers of items and ultimately the acquisition of more abstract numerical skills. Here, we investigated whether excessive crowding occurs in developmental dyscalculia (DD), a neurodevelopmental disorder characterized by difficulty in learning the most basic numerical and arithmetical concepts, and whether it is found independently of associated major reading and attentional difficulties. We measured spatial crowding in two groups of adult individuals with DD and control subjects. In separate experiments, participants were asked to discriminate the orientation of a Gabor patch either in isolation or under spatial crowding. Orientation discrimination thresholds were comparable across groups when stimuli were shown in isolation, yet they were much higher for the DD group with respect to the control group when the target was crowded by closely neighbouring flanking gratings. The difficulty in discriminating orientation (as reflected by the combination of accuracy and reaction times) in the DD compared to the control group persisted over several larger target flanker distances. Finally, we found that the degree of such spatial crowding correlated with impairments in mathematical abilities even when controlling for visual attention and reading skills. These results suggest that excessive crowding effects might be a characteristic of DD, independent of other associated neurodevelopmental disorders. Castaldi, E., Turi, M., Gassama, S., Piazza, M., & Eger, E. https://www.pisavisionlab.org/2020/08/01/excessive-visual-crowding-effects-in-developmental-dyscalculia/i0035-8711-20-8-7/https://doi.org/10.1167/jov.20.8.7 https://www.pisavisionlab.org/2020/08/24/groupitizing-a-strategy-for-numerosity-estimation/ Mon, 24 Aug 2020 15:13:43 +0000 https://www.pisavisionlab.org/?p=3100 Scientific Reports, 10(1), 13436 Previous work has shown that when arrays of objects are grouped within clusters, participants can enumerate their numerosity more rapidly than when objects are randomly scattered, a phenomenon termed “groupitizing”. Importantly, the magnitude of the grouping advantage correlates with math abilities in children. Here we show that sensory precision of numerosity estimation is also improved when grouping cues are available, by up to 20%. The grouping can be induced by color and/or spatial proximity, and occurs in temporal sequences as well as spatial arrays. The improvement is strongest for participants with the highest thresholds in the random, ungrouped conditions. Taken together with previous research, our data suggest that measurements correlations between numerosity estimation and formal math skills may be driven by grouping strategies, which require a minimal level of basic arithmetic. Anobile, G., Castaldi, E., Moscoso, P. A. M., Burr, D. C., & Arrighi, R. https://www.pisavisionlab.org/2020/08/24/groupitizing-a-strategy-for-numerosity-estimation/s41598-020-68111-1/https://doi.org/10.1038/s41598-020-68111-1 https://www.pisavisionlab.org/2020/08/24/horace-barlow-1921-2020/ Mon, 24 Aug 2020 15:45:32 +0000 https://www.pisavisionlab.org/?p=3105 Current Biology July 2020 Horace Barlow was one of the truly great neuroscientists of his time, in the Cambridge tradition of quantitative neurophysiology and psychophysics. His fundamental theoretical and empirical contributions to our understanding of brain function have inspired and influenced generations of neurophysiologists, psychologists and computational neuroscientists and are certain to endure for generations to come. David Burr; Simon Laughlin https://www.pisavisionlab.org/2020/08/24/horace-barlow-1921-2020/piis096098222031085x/https://doi.org/10.1016/j.cub.2020.07.060 https://www.pisavisionlab.org/2020/08/24/adaptation-to-hand-tapping-affects-sensory-processing-of-numerosity-directly-evidence-from-reaction-times-and-confidence-2/ Mon, 24 Aug 2020 16:12:44 +0000 https://www.pisavisionlab.org/?p=3115 Proceedings of the Royal Society B: Biological Sciences, 287(1927), 20200801 Like most perceptual attributes, the perception of numerosity is susceptible to adaptation, both to prolonged viewing of spatial arrays and to repeated motor actions such as hand-tapping. However, the possibility has been raised that adaptation may reflect response biases rather than modification of sensory processing. To disentangle these two possibilities, we studied visual and motor adaptation of numerosity perception while measuring confidence and reaction times. Both sensory and motor adaptation robustly distorted numerosity estimates, and these shifts in perceived numerosity were accompanied by similar shifts in confidence and reaction-time distributions. After adaptation, maximum uncertainty and slowest response-times occurred at the point of subjective (rather than physical) equality of the matching task, suggesting that adaptation acts directly on the sensory representation of numerosity, before the decisional processes. On the other hand, making reward response-contingent, which also caused robust shifts in the psychometric function, caused no significant shifts in confidence or reaction-time distributions. These results reinforce evidence for shared mechanisms that encode the quantity of both internally and externally generated events, and advance a useful general technique to test whether contextual effects like adaptation and serial dependence really affect sensory processing. Maldonado Moscoso, P. A., Cicchini, G. M., Arrighi, R., & Burr, D. C. https://www.pisavisionlab.org/2020/08/24/adaptation-to-hand-tapping-affects-sensory-processing-of-numerosity-directly-evidence-from-reaction-times-and-confidence-2/adaptation-to-hand-tapping-affects-sensory-processing-of-numerosity-directly-evidence-from-reaction-times-and-confidence-2/https://doi.org/10.1098/rspb.2020.0801 https://www.pisavisionlab.org/2020/08/25/the-visual-white-matter-connecting-human-area-prostriata-and-the-thalamus-is-retinotopically-organized/ Tue, 25 Aug 2020 08:55:37 +0000 https://www.pisavisionlab.org/?p=3132 Brain Structure and Function, 1-15 The human visual system is capable of processing visual information from fovea to the far peripheral visual feld. Recent fMRI studies have shown a full and detailed retinotopic map in area prostriata, located ventro-dorsally and anterior to the calcarine sulcus along the parieto-occipital sulcus with strong preference for peripheral and wide-feld stimulation. Here, we report the anatomical pattern of white matter connections between area prostriata and the thalamus encompassing the lateral geniculate nucleus (LGN). To this end, we developed and utilized an automated pipeline comprising a series of Apps that run openly on the cloud computing platform brainlife.io to analyse 139 subjects of the Human Connectome Project (HCP). We observe a continuous and extended bundle of white matter fbers from which two subcomponents can be extracted: one passing ventrally parallel to the optic radiations (OR) and another passing dorsally circumventing the lateral ventricle. Interestingly, the loop travelling dorsally connects the thalamus with the central visual feld representation of prostriata located anteriorly, while the other loop travelling more ventrally connects the LGN with the more peripheral visual feld representation located posteriorly. We then analyse an additional cohort of 10 HCP subjects using a manual plane extraction method outside brainlife.io to study the relationship between the two extracted white matter subcomponents and eccentricity, myelin and cortical thickness gradients within prostriata. Our results are consistent with a retinotopic segregation recently demonstrated in the OR, connecting the LGN and V1 in humans and reveal for the frst time a retinotopic segregation regarding the trajectory of a fber bundle between the thalamus and an associative visual area. JW Kurzawski, K Mikellidou, MC Morrone, F Pestilli https://www.pisavisionlab.org/2020/08/25/the-visual-white-matter-connecting-human-area-prostriata-and-the-thalamus-is-retinotopically-organized/the_visual_white_matter_connecting_human_area_pros/https://doi.org/10.1007/s00429-020-02096-5 https://www.pisavisionlab.org/2020/09/24/fast-saccadic-eye-movements-in-humans-suggest-that-numerosity-perception-is-automatic-and-direct/ Thu, 24 Sep 2020 13:00:59 +0000 https://www.pisavisionlab.org/?p=3160 Proceedings of the Royal Society B: Biological Sciences, 287(1935), 20201884 Fast saccades are rapid automatic oculomotor responses to salient and ecologically important visual stimuli such as animals and faces. Discriminating the number of friends, foe, or prey may also have an evolutionary advantage. In this study, participants were asked to saccade rapidly towards the more numerous of two arrays. Participants could discriminate numerosities with high accuracy and great speed, as fast as 190 ms. Intermediate numerosities were more likely to elicit fast saccades than very low or very high numerosities. Reaction-times for vocal responses (collected in a separate experiment) were slower, did not depend on numerical range, and correlated only with the slow not the fast saccades, pointing to different systems. The short saccadic reaction-times we observe are surprising given that discrimination using numerosity estimation is thought to require a relatively complex neural circuit, with several relays of information through the parietal and prefrontal cortex. Our results suggest that fast numerosity-driven saccades may be generated on a single feed-forward pass of information recruiting a primitive system that cuts through the cortical hierarchy and rapidly transforms the numerosity information into a saccade command. Castaldi, E., Burr, D., Turi, M., & Binda, P. https://www.pisavisionlab.org/2020/09/24/fast-saccadic-eye-movements-in-humans-suggest-that-numerosity-perception-is-automatic-and-direct/rspb-2020-1884/https://doi.org/10.1098/rspb.2020.1884 https://www.pisavisionlab.org/2020/09/24/fast-saccadic-eye-movements-in-humans-suggest-that-numerosity-perception-is-automatic-and-direct-2/ Thu, 24 Sep 2020 13:13:03 +0000 https://www.pisavisionlab.org/?p=3164 Proc. R. Soc. B 287: 20201884. Fast saccades are rapid automatic oculomotor responses to salient and ecologically important visual stimuli such as animals and faces. Discriminating the number of friends, foe, or prey may also have an evolutionary advantage. In this study, participants were asked to saccade rapidly towards the more numerous of two arrays. Participants could discriminate numerosities with high accuracy and great speed, as fast as 190 ms. Intermediate numerosities were more likely to elicit fast saccades than very low or very high numerosities. Reaction-times for vocal responses (collected in a separate experiment) were slower, did not depend on numerical range, and correlated only with the slow not the fast saccades, pointing to different systems. The short saccadic reaction-times we observe are surprising given that discrimination using numerosity estimation is thought to require a relatively complex neural circuit, with several relays of information through the parietal and prefrontal cortex. Our results suggest that fast numerosity-driven saccades may be generated on a single feed-forward pass of information recruiting a primitive system that cuts through the cortical hierarchy and rapidly transforms the numerosity information into a saccade command. Elisa Castaldi, David Burr, Marco Turi and Paola Binda https://doi.org/10.5061/dryad.7d7wm37s6 https://www.pisavisionlab.org/2020/10/09/spontaneous-pupillary-oscillations-increase-during-mindfulness-meditation/ Fri, 09 Oct 2020 14:37:09 +0000 https://www.pisavisionlab.org/?p=3218 Current Biology Volume 30, Issue 18, 21 September 2020, Pages R1030-R1031 A significant body of literature has shown that pupil size varies with cognitive and perceptual states [1,2]. Furthermore, the pupil diameter oscillates spontaneously at low frequencies, sometimes referred to as pupillary hippus [3,4]. Oscillation amplitude varies with many neural factors, including arousal and cortical excitability. Here we show that pupillary oscillations are modulated by mindfulness meditation, increasing by 53% compared to pre- and post-meditation baselines. The effect occurs only in trained meditators and is specific for low frequencies (below 1 Hz), with delta frequencies (1–5 Hz) unchanged. The study suggests that pupil size may be a useful marker of the altered cortical state during meditation. Antonella Pomè, David C.Burr, Annalisa Capuozzo, Paola Binda https://www.pisavisionlab.org/2020/10/09/spontaneous-pupillary-oscillations-increase-during-mindfulness-meditation/1-s2-0-s0960982220310897-main/https://doi.org/10.1016/j.cub.2020.07.064 https://www.pisavisionlab.org/2020/10/09/non-spatial-skills-differ-in-the-front-and-rear-peri-personal-space/ Fri, 09 Oct 2020 14:43:51 +0000 https://www.pisavisionlab.org/?p=3223 Neuropsychologia Volume 147, October 2020, 107619 In measuring behavioural and pupillary responses to auditory oddball stimuli delivered in the front and rear peri-personal space, we find that pupils dilate in response to rare stimuli, both target and distracters. Dilation in response to targets is stronger than the response to distracters, implying a task relevance effect on pupil responses. Crucially, pupil dilation in response to targets is also selectively modulated by the location of sound sources: stronger in the front than in the rear peri-personal space, in spite of matching behavioural performance. This supports the concept that even non-spatial skills, such as the ability to alert in response to behaviourally relevant events, are differentially engaged across subregions of the peri-personal space. Elena Aggius-Vella, Monica Gori, Silvia Animali, Claudio Campus, Paola Binda https://www.pisavisionlab.org/2020/10/09/non-spatial-skills-differ-in-the-front-and-rear-peri-personal-space/1-s2-0-s0028393220302918-main/https://doi.org/10.1016/j.neuropsychologia.2020.107619 https://www.pisavisionlab.org/2020/10/09/adaptation-to-the-speed-of-biological-motion-in-autism-2/ Fri, 09 Oct 2020 14:47:27 +0000 https://www.pisavisionlab.org/?p=3224 Journal of Autism and Developmental Disorders, 50(2), 373–385 Autistic individuals often present atypicalities in adaptation—the continuous recalibration of perceptual systems driven by recent sensory experiences. Here, we examined such atypicalities in human biological motion. We used a dual-task paradigm, including a running-speed discrimination task (‘comparing the speed of two running silhouettes’) and a change-detection task (‘detecting fixation-point shrinkages’) assessing attention. We tested 19 school-age autistic and 19 age- and ability-matched typical participants, also recording eye-movements. The two groups presented comparable speed-discrimination abilities and, unexpectedly, comparable adaptation. Accuracy in the change-detection task and the scatter of eye-fixations around the fixation point were also similar across groups. Yet, the scatter of fixations reliably predicted the magnitude of adaptation, demonstrating the importance of controlling for attention in adaptation studies. Karaminis, T., Arrighi, R., Forth, G., Burr, D., & Pellicano, E. https://www.pisavisionlab.org/2020/10/09/adaptation-to-the-speed-of-biological-motion-in-autism-2/karaminis2020_article_adaptationtothespeedofbiologic/https://doi.org/10.1007/s10803-019-04241-4 https://www.pisavisionlab.org/2020/10/09/learning-disabilities-developmental-dyscalculia/ Fri, 09 Oct 2020 14:58:12 +0000 https://www.pisavisionlab.org/?p=3236 In A. Gallagher, C. Bulteau, D. Cohen, & J. L. Michaud (Eds.), Handbook of Clinical Neurology (Vol. 174, pp. 61–75). Elsevier Developmental dyscalculia (DD) is a developmental learning disability that manifests as a persistent difficulty in comprehending even the most basic numeric and arithmetic concepts, despite normal intelligence and schooling opportunities. Given the predominant use of numbers in modern society, this condition can pose major challenges in the sufferer’s everyday life, both in personal and professional development. Since, to date, we still lack a universally recognized and psychometrically driven definition of DD, its diagnosis has been applied to a wide variety of cognitive profiles. In this chapter, we review the behavioral and neural characterization of DD as well as the different neurocognitive and etiologic accounts of this neurodevelopmental disorder. We underline the multicomponential nature of this heterogeneous disability: different aspects of mathematical competence can be affected by both the suboptimal recruitment of general cognitive functions supporting mathematical cognition (such as attention, memory, and cognitive control) and specific deficits in mastering numeric concepts and operations. Accordingly, both intervention paradigms focused on core numeric abilities and more comprehensive protocols targeting multiple neurocognitive systems have provided evidence for effective positive outcomes. Castaldi, E., Piazza, M., & Iuculano, T. https://doi.org/10.1016/B978-0-444-64148-9.00005-3 https://www.pisavisionlab.org/2020/10/09/grouping-strategies-in-number-estimation-extend-the-subitizing-range/ Fri, 09 Oct 2020 14:58:57 +0000 https://www.pisavisionlab.org/?p=3235 Scientific Reports, 10(1), 14979 When asked to estimate the number of items in a visual array, educated adults and children are more precise and rapid if the items are clustered into small subgroups rather than randomly distributed. This phenomenon, termed “groupitizing”, is thought to rely on the recruitment of the subitizing system (dedicated to the perception of very small numbers), with the aid of simple arithmetical calculations. The aim of current study is to verify whether the advantage for clustered stimuli does rely on subitizing, by manipulating attention, known to strongly affect attention. Participants estimated the numerosity of grouped or ungrouped arrays in condition of full attention or while attention was diverted with a dual-task. Depriving visual attention strongly decreased estimation precision of grouped but not of ungrouped arrays, as well as increasing the tendency for numerosity estimation to regress towards the mean. Additional explorative analyses suggested that calculation skills correlated with the estimation precision of grouped, but not of ungrouped, arrays. The results suggest that groupitizing is an attention-based process that leverages on the subitizing system. They also suggest that measuring numerosity estimation thresholds with grouped stimuli may be a sensitive correlate of math abilities. Maldonado Moscoso, P. A., Castaldi, E., Burr, D. C., Arrighi, R., & Anobile, G. https://www.pisavisionlab.org/2020/10/09/grouping-strategies-in-number-estimation-extend-the-subitizing-range/s41598-020-71871-5/https://doi.org/10.1038/s41598-020-71871-5 https://www.pisavisionlab.org/2020/10/09/object-identity-determines-trans-saccadic-integration/ Fri, 09 Oct 2020 15:04:10 +0000 https://www.pisavisionlab.org/?p=3245 Journal of Vision July 2020, Vol.20, 33 Humans make two to four rapid eye movements (saccades) per second, which, surprisingly, does not lead to abrupt changes in vision. To the contrary, we perceive a stable world. Hence, an important question is how information is integrated across saccades. To investigate this question, we used the sequential metacontrast paradigm (SQM), where two expanding streams of lines are presented. When one line is spatially offset, the other lines are perceived as being offset, too. When more lines are offset, all offsets integrate mandatorily; that is, observers cannot report the individual offsets but perceive one integrated offset. Here, we asked observers to make a saccade during the SQM. Even though the saccades caused a highly disrupted motion trajectory on the retina, offsets presented before and after the saccade integrated mandatorily. When observers made no saccade and the streams were displaced on the screen so that a similarly disrupted retinal image occurred as in the previous condition, no integration occurred. We suggest that trans-saccadic integration and perception are determined by object identity in spatiotopic coordinates and not by the retinal image. Leila Drissi-Daoudi; Haluk Öğmen; Michael H. Herzog; Guido Marco Cicchini https://www.pisavisionlab.org/2020/10/09/object-identity-determines-trans-saccadic-integration/i0035-8711-719-1-07244/https://doi.org/10.1167/jov.20.7.33 https://www.pisavisionlab.org/2020/10/09/perceptual-oscillations-in-gender-classification-of-faces-contingent-on-stimulus-history/ Fri, 09 Oct 2020 15:06:15 +0000 https://www.pisavisionlab.org/?p=3249 iScience Volume 23, Issue 10, 23 October 2020, 101573 Perception is a proactive ‘‘predictive’’ process, in which the brain takes advantage of past experience to make informed guesses about the world to test against sensory data. Here we demonstrate that in the judgment of the gender of faces, beta rhythms play an important role in communicating perceptual experience. Observers classified in forced choice as male or female, a sequence of face stimuli, which were physically constructed to be male or female or androgynous (equal morph). Classification of the androgynous stimuli oscillated rhythmically between male and female, following a complex waveform comprising 13.5 and 17 Hz. Parsing the trials based on the preceding stimulus showed that responses to androgynous stimuli preceded by male stimuli oscillated reliably at 17 Hz, whereas those preceded by female stimuli oscillated at 13.5 Hz. These results suggest that perceptual priors for face perception from recent perceptual memory are communicated through frequency-coded beta rhythms. Jason Bell, David C.Burr, Kate Crookes, Maria Concetta Morrone https://www.pisavisionlab.org/2020/10/09/perceptual-oscillations-in-gender-classification-of-faces-contingent-on-stimulus-history/1-s2-0-s2589004220307653-main/https://doi.org/10.1016/j.isci.2020.101573 https://www.pisavisionlab.org/2020/10/09/the-role-of-temporal-and-spatial-attention-in-size-adaptation/ Fri, 09 Oct 2020 15:11:12 +0000 https://www.pisavisionlab.org/?p=3259 Frontiers in Neuroscience, 14, 539 One of the most important tasks for the visual system is to construct an internal representation of the spatial properties of objects, including their size. Size perception includes a combination of bottom-up (retinal inputs) and top-down (e.g., expectations) information, which makes the estimates of object size malleable and susceptible to numerous contextual cues. For example, it has been shown that size perception is prone to adaptation: brief previous presentations of larger or smaller adapting stimuli at the same region of space changes the perceived size of a subsequent test stimulus. Large adapting stimuli cause the test to appear smaller than its veridical size and vice versa. Here, we investigated whether size adaptation is susceptible to attentional modulation. First, we measured the magnitude of adaptation aftereffects for a size discrimination task. Then, we compared these aftereffects (on average 15–20%) with those measured while participants were engaged, during the adaptation phase, in one of the two highly demanding central visual tasks: Multiple Object Tracking (MOT) or Rapid Serial Visual Presentation (RSVP). Our results indicate that deploying visual attention away from the adapters did not significantly affect the distortions of perceived size induced by adaptation, with accuracy and precision in the discrimination task being almost identical in all experimental conditions. Taken together, these results suggest that visual attention does not play a key role in size adaptation, in line with the idea that this phenomenon can be accounted for by local gain control mechanisms within area V1. Tonelli, A., Pooresmaeili, A., & Arrighi, R. https://www.pisavisionlab.org/2020/10/09/the-role-of-temporal-and-spatial-attention-in-size-adaptation/fnins-14-00539/https://doi.org/10.3389/fnins.2020.00539 https://www.pisavisionlab.org/2020/10/09/temporal-context-affects-interval-timing-at-the-perceptual-level/ Fri, 09 Oct 2020 15:11:22 +0000 https://www.pisavisionlab.org/?p=3260 Sci Rep 10, 8767 (2020) There is now ample evidence that when observers are asked to estimate features of an object they take into account recent stimulation history and blend the current sensory evidence with the recent stimulus intensity according to their reliability. Most of this evidence has been obtained via estimation or production paradigms both of which entail a conspicuous post-perceptual decision stage. So it is an unsolved question, as to whether the trace of previous stimulation contributes at the decision stage or as early as the perceptual stage. To this aim we focused on duration judgments, which typically exhibit strong central tendency effects and asked a duration comparison between two intervals, one of which characterized by high uncertainty. We found that the perceived duration of this interval regressed toward the average duration, demonstrating a genuine perceptual bias. Regression did not transfer between the visual and the auditory modality, indicating it is modality specific, but generalized across passively observed and actively produced intervals. These findings suggest that temporal central tendency effects modulate how long an interval appears to us and that integration of current sensory evidence can occur as early as in the sensory systems. Eckart Zimmermann & Guido Marco Cicchini https://www.pisavisionlab.org/2020/10/09/temporal-context-affects-interval-timing-at-the-perceptual-level/s41598-020-65609-6/https://doi.org/10.1038/s41598-020-65609-6 https://www.pisavisionlab.org/2020/10/09/the-shared-numerical-representation-for-action-and-perception-develops-independently-from-vision-2/ Fri, 09 Oct 2020 15:14:43 +0000 https://www.pisavisionlab.org/?p=3269 Cortex, 129, 436–445 Humans share with other animals a number sense, a system allowing a rapid and approximate estimate of the number of items in a scene. Recently, it has been shown that numerosity is shared between action and perception as the number of repetitions of self-produced actions affects the perceived numerosity of subsequent visual stimuli presented around the area where actions occurred. Here we investigate whether this interplay between action and perception for numerosity depends on visual input and visual experience. We measured the effects of adaptation to motor routines (finger tapping) on numerical estimates of auditory sequences in sighted and congenitally blind people. In both groups, our results show a consistent adaptation effect with relative under- or over-estimation of perceived auditory numerosity following rapid or slow tapping adaptation, respectively. Moreover, adaptation occurred around the tapping area irrespective of the hand posture (crossed or uncrossed hands), indicating that motor adaptation was coded using external (not hand-centred) coordinates in both groups. Overall, these results support the existence of a generalized interaction between action and perception for numerosity that occurs in external space and manifests independently of visual input or even visual experience. Togoli, I., Crollen, V., Arrighi, R., & Collignon, O. https://www.pisavisionlab.org/2020/10/09/the-shared-numerical-representation-for-action-and-perception-develops-independently-from-vision-2/1-s2-0-s001094522030191x-main/https://doi.org/10.1016/j.cortex.2020.05.004 https://www.pisavisionlab.org/2020/10/09/spontaneous-pupillary-oscillations-increase-during-mindfulness-meditation-2/ Fri, 09 Oct 2020 15:44:45 +0000 https://www.pisavisionlab.org/?p=3273 Current Biology Volume 30, Issue 18, 21 September 2020, Pages R1030-R1031 A significant body of literature has shown that pupil size varies with cognitive and perceptual states [1,2]. Furthermore, the pupil diameter oscillates spontaneously at low frequencies, sometimes referred to as pupillary hippus [3,4]. Oscillation amplitude varies with many neural factors, including arousal and cortical excitability. Here we show that pupillary oscillations are modulated by mindfulness meditation, increasing by 53% compared to pre- and post-meditation baselines. The effect occurs only in trained meditators and is specific for low frequencies (below 1 Hz), with delta frequencies (1–5 Hz) unchanged. The study suggests that pupil size may be a useful marker of the altered cortical state during meditation. Antonella Pome' ; David C. Burr; Analisa Capuozzo; Paola Binda https://doi.org/10.5281/zenodo.3939009 https://www.pisavisionlab.org/2020/11/12/pupillometry-in-mind-wandering-and-non-trial-based-experiments/ Thu, 12 Nov 2020 16:28:42 +0000 https://www.pisavisionlab.org/?p=3376 ["live talk"] Advancing Methods for Pupillometry conference 2020 (on-line event) Paola Binda https://www.pisavisionlab.org/2020/11/16/location-and-object-based-attention-enhance-number-estimation/ Mon, 16 Nov 2020 09:55:43 +0000 https://www.pisavisionlab.org/?p=3382 Atten Percept Psychophys (2020) Humans and non-humans can extract an estimate of the number of items in a collection very rapidly, raising the question of whether attention is necessary for this process. Visual attention operates in various modes, showing selectivity both to spatial location and to objects. Here, we tested whether each form of attention can enhance number estimation, by measuring whether presenting a visual cue to increase attentional engagement will lead to a more accurate and precise representation of number, both when attention is directed to location and when it is directed to objects. Results revealed that enumeration of a collection of dots in the location previously cued led to faster, more precise, and more accurate judgments than enumeration in un-cued locations, and a similar benefit was seen when the cue and collection appeared on the same object. This work shows that like many other perceptual tasks, numerical estimation may be enhanced by the spread of active attention inside a pre-cued object. Antonella Pomè, Diego Thompson, David Charles Burr & Justin Halberda https://www.pisavisionlab.org/2020/11/16/location-and-object-based-attention-enhance-number-estimation/pome2020_article_location-andobject-basedattent/https://doi.org/10.3758/s13414-020-02178-w https://www.pisavisionlab.org/2020/11/17/pupillary-responses-obey-emmerts-law-and-co-vary-with-autistic-traits/ Tue, 17 Nov 2020 17:09:34 +0000 https://www.pisavisionlab.org/?p=3389 J Autism Dev Disord (2020) We measured the pupil response to a light stimulus subject to a size illusion and found that stimuli perceived as larger evoke a stronger pupillary response. The size illusion depends on combining retinal signals with contextual 3D information; contextual processing is thought to vary across individuals, being weaker in individuals with stronger autistic traits. Consistent with this theory, autistic traits correlated negatively with the magnitude of pupil modulations in our sample of neurotypical adults; however, psychophysical measurements of the illusion did not correlate with autistic traits, or with the pupil modulations. This shows that pupillometry provides an accurate objective index of complex perceptual processes, particularly useful for quantifying interindividual differences, and potentially more informative than standard psychophysical measures. Chiara Tortelli, Marco Turi, David C. Burr & Paola Binda https://www.pisavisionlab.org/2020/11/17/pupillary-responses-obey-emmerts-law-and-co-vary-with-autistic-traits/tortelli2020_article_pupillaryresponsesobeyemmertsl/https://doi.org/10.1007/s10803-020-04718-7 https://www.pisavisionlab.org/2020/11/23/a-sensorimotor-numerosity-system/ Mon, 23 Nov 2020 09:32:20 +0000 https://www.pisavisionlab.org/?p=3471 Trends in Cognitive Sciences, 25(1), 24–36 Incoming sensory input provides information for the planning and execution of actions, which yield motor outcomes that are themselves sensory inputs. One dimension where action and perception strongly interact is numerosity perception. Many non-human animals can estimate approximately the number of external elements as well as their own actions, and neurons have been identified that respond to both. Recent psychophysical adaptation studies on humans also provide evidence for neural mechanisms responding to both the number of externally generated events and self-produced actions. Here we advance the idea that these strong connections may arise from dedicated sensorimotor mechanisms in the brain, part of a more generalized system interfacing action with the processing of other quantitative magnitudes such as space and time. Anobile, G., Arrighi, R., Castaldi, E., & Burr, D. C. https://www.pisavisionlab.org/2020/11/23/a-sensorimotor-numerosity-system/1-s2-0-s1364661320302709-main/https://doi.org/10.1016/j.tics.2020.10.009 https://www.pisavisionlab.org/2020/11/26/pupillary-response-to-representations-of-light-in-paintings/ Thu, 26 Nov 2020 15:02:50 +0000 https://www.pisavisionlab.org/?p=3483 Journal of Vision, 20(10), 14–14. It is known that, although the level of light is the primary determinant of pupil size, cognitive factors can also affect pupil diameter. It has been demonstrated that photographs of the sun produce pupil constriction independently of their luminance and other low-level features, suggesting that high-level visual processing may also modulate pupil response. Here, we measure pupil response to artistic paintings of the sun, moon, or containing a uniform lighting, that, being mediated by the artist’s interpretation of reality and his technical rendering, require an even higher level of interpretation compared with photographs. We also study how chromatic content and spatial layout affect the results by presenting grey-scale and inverted versions of each painting. Finally, we assess directly with a categorization test how subjective image interpretation affects pupil response. We find that paintings with the sun elicit a smaller pupil size than paintings with the moon, or paintings containing no visible light source. The effect produced by sun paintings is reduced by disrupting contextual information, such as by removing color or manipulating the relations between paintings features that make more difficult to identify the source of light. Finally, and more importantly, pupil diameter changes according to observers’ interpretation of the scene represented in the same stimulus. In conclusion, results show that the subcortical pupillary response to light is modulated by subjective interpretation of luminous objects, suggesting the involvement of cortical systems in charge of cognitive processes, such as attention, object recognition, familiarity, memory, and imagination. Castellotti, S., Conti, M., Feitosa-Santana, C., & Del Viva, M. M. https://www.pisavisionlab.org/2020/11/26/pupillary-response-to-representations-of-light-in-paintings/i1534-7362-20-10-14_1602668521-01028/ https://doi.org/10.1167/jov.20.10.14 https://www.pisavisionlab.org/2020/12/16/not-only-faces-specialized-visual-representation-of-human-hands-revealed-by-adaptation/ Wed, 16 Dec 2020 15:49:52 +0000 https://www.pisavisionlab.org/?p=3510 Royal Society, Open Science Classical neurophysiological studies demonstrated that the monkey brain is equipped with neurons selectively representing the visual shape of the primate hand. Neuroimaging in humans provided data suggesting that a similar representation can be found in humans. Here, we investigated the selectivity of hand representation in humans by means of the visual adaptation technique. Results showed that participants' judgement of human-likeness of a visual probe representing a human hand was specifically reduced by a visual adaptation procedure when using a human hand adaptor but not when using an anthropoid robotic hand or a non-primate animal paw adaptor. Instead, human-likeness of the anthropoid robotic hand was affected by both human and robotic adaptors. No effect was found when using a non-primate animal paw as adaptor or probe. These results support the existence of specific neural mechanisms encoding human hand in the human's visual system. Massimiliano Conson, Francesco Polito, Alessandro Di Rosa, Luigi Trojano, Gennaro Cordasco, Anna Esposito and Marco Turi https://www.pisavisionlab.org/2020/12/16/not-only-faces-specialized-visual-representation-of-human-hands-revealed-by-adaptation/rsos-200948/https://doi.org/10.1098/rsos.200948 https://www.pisavisionlab.org/2021/01/12/perceptual-history-propagates-down-to-early-levels-of-sensory-analysis/ Tue, 12 Jan 2021 08:50:03 +0000 https://www.pisavisionlab.org/?p=3544 Current Biology, 31(6), 1245-1250.e2. One function of perceptual systems is to construct and maintain a reliable representation of the environment. A useful strategy intrinsic to modern “Bayesian” theories of perception1, 2, 3, 4, 5, 6 is to take advantage of the relative stability of the input and use perceptual history (priors) to predict current perception. This strategy is efficient1, 2, 3, 4, 5, 6, 7 but can lead to stimuli being biased toward perceptual history, clearly revealed in a phenomenon known as serial dependence.8, 9, 10, 11, 12, 13, 14 However, it is still unclear whether serial dependence biases sensory encoding or only perceptual decisions.15,16 We leveraged on the “surround tilt illusion”—where tilted flanking stimuli strongly bias perceived orientation—to measure its influence on the pattern of serial dependence, which is typically maximal for similar orientations of past and present stimuli.7,10 Maximal serial dependence for a neutral stimulus preceded by an illusory one occurred when the perceived, not the physical, orientations of the two stimuli matched, suggesting that the priors biasing current perception incorporate the effect of the illusion. However, maximal serial dependence of illusory stimuli induced by neutral stimuli occurred when their physical (not perceived) orientations were matched, suggesting that priors interact with incoming sensory signals before they are biased by flanking stimuli. The evidence suggests that priors are high-level constructs incorporating contextual information, which interact directly with early sensory signals, not with highly processed perceptual representations. Cicchini, G. M., Benedetto, A., & Burr, D. C. https://www.pisavisionlab.org/2021/01/12/perceptual-history-propagates-down-to-early-levels-of-sensory-analysis/1-s2-0-s0960982220318248-main/https://doi.org/10.1016/j.cub.2020.12.004 https://www.pisavisionlab.org/2021/01/12/perceptual-history-propagates-down-to-early-levels-of-sensory-analysis-2/ Tue, 12 Jan 2021 08:57:57 +0000 https://www.pisavisionlab.org/?p=3551 Current Biology One function of perceptual systems is to construct and maintain a reliable representation of the environment. A useful strategy intrinsic to modern “Bayesian” theories of perception is to take advantage of the relative stability of the input and use perceptual history (priors) to predict current perception. This strategy is efficient but can lead to stimuli being biased toward perceptual history, clearly revealed in a phenomenon known as serial dependence. However, it is still unclear whether serial dependence biases sensory encoding or only perceptual decisions. We leveraged on the “surround tilt illusion”—where tilted flanking stimuli strongly bias perceived orientation—to measure its influence on the pattern of serial dependence, which is typically maximal for similar orientations of past and present stimuli. Maximal serial dependence for a neutral stimulus preceded by an illusory one occurred when the perceived, not the physical, orientations of the two stimuli matched, suggesting that the priors biasing current perception incorporate the effect of the illusion. However, maximal serial dependence of illusory stimuli induced by neutral stimuli occurred when their physical (not perceived) orientations were matched, suggesting that priors interact with incoming sensory signals before they are biased by flanking stimuli. The evidence suggests that priors are high-level constructs incorporating contextual information, which interact directly with early sensory signals, not with highly processed perceptual representations. Cicchini, Guido Marco; Benedetto, Alessandro; Burr, David https://zenodo.org/record/4362291#.X94jCthKhPY https://www.pisavisionlab.org/2021/01/15/voluntary-action-rhythmically-modulates-7t-bold-visual-responses-in-primary-visual-cortex-2/ Fri, 15 Jan 2021 12:50:40 +0000 https://www.pisavisionlab.org/?p=3594 ["digital poster"] AIRMM XI Congress Behavioral visual sensitivity varies rhythmically over time when synchronized by an attention cue, a sensory stimulus, or the onset of a voluntary action. These rhythms may emerge from phase-resetting of endogenous neuronal oscillations by motor preparation, implicating them in sensory-motor coordination. Here we measure the BOLD correlates of behavioral oscillations by monitoring activity in early visual and motor cortex, using ultra-high field fMRI (GE MR950 7T research system). METHODS Participants (21 healthy adults) made voluntary keypresses (one every 30 s on average) followed by a brief (33 ms) visual stimulus, with four possible delays between the keypress and the visual stimulus (70, 150, 230, 310 ms). The visual presentation consisted of two half-gratings with slightly different spatial frequencies; participants were instructed to report which half-grating had the higher spatial frequency, with a second keypress (different key). fMRI sequences were T2*-weighted GE-EPI with TR = 3 s and 1.5 mm isotropic voxels. Functional data were corrected for EPI distortions, motion and slice-time acquisition, and aligned to high-resolution 3D anatomies (FSPGR 1mm isotropic voxels) with FSL/Freesurfer. fMRI data were also projected to the cortical surfaces of the individual subject and to an average surface template. We defined regions of interest over primary visual cortex V1 and later visual areas using retinotopic mapping data acquired in a separate scan. We also placed regions of interest over the motor and somatosensory cortex using responses to keypresses-only events, made to perform the discrimination task. Within these visual and somatosensory/motor regions, we analyzed BOLD responses to keypress+visual events, i.e. keypresses immediately followed by the visual stimulation. RESULTS We find that visual-evoked BOLD responses in V1 are strongly modulated by voluntary actions (keypresses). V1 activity is modulated by the delay between the keypress and the visual stimulus: lower for stimuli delivered 70 ms or 230 ms after the keypress, higher for stimuli at 150 ms or 310 ms, paralleling the behavioral oscillations of visual sensitivity. A similar oscillatory pattern is seen across early visual areas, but no such effect is seen in motor and somatosensory cortex. Nevertheless, we find strong and systematic associations between M1 activity at the time of voluntary keypress and V1 modulations, suggesting that cortical connectivity between these areas drives the oscillation of visual sensitivity. Our findings are consistent with EEG and behavioral studies and suggest that motor cortex modulates the output signals from early visual cortex to prioritize the processing of information relevant for visuo-motor coordination, and that this mechanism may rely on synchronization of endogenous rhythms. Alessandro Benedetto, Paola Binda, Mauro Costagli, Michela Tosetti, and Maria Concetta Morrone https://www.pisavisionlab.org/2021/01/15/voluntary-action-rhythmically-modulates-7t-bold-visual-responses-in-primary-visual-cortex-2/eposterbenedetto/ https://www.pisavisionlab.org/2021/11/24/subitizing-unlike-estimation-does-not-process-sets-in-parallel/ Wed, 24 Nov 2021 20:35:31 +0000 https://www.pisavisionlab.org/?p=3986 Scientific Reports, 10(1), 15689 Enumeration of very small quantities is a common task that we perform everyday. Much research has highlighted that in these conditions humans display fast, near errorless performance, a phenomenon dubbed subitizing. It has been suggested that this regime has a pivotal role in numerosity perception. Here we asked if this system can process multiple sets of items in parallel. At odds with what happens for moderate numerosities, we found a strong impairment caused already by the introduction of a second group of items marked by a different color. Adding shape as a cue provided no benefit. The only case in which subitizing was possible was when the target and distractor group were held constant through the experimental block. These results show the surprising fact that whilst being rapid and errorless, subitizing does not have the capability to disentangle multiple groups of items and deals only with coarse stimulus statistics. Liu, W., Zheng, P., Huang, S., & Cicchini, G. M. https://www.pisavisionlab.org/2021/11/24/subitizing-unlike-estimation-does-not-process-sets-in-parallel/s41598-020-72860-4/https://doi.org/10.1038/s41598-020-72860-4