https://www.pisavisionlab.org Research centre dedicated to frontier, interdisciplinary research of human perception Wed, 24 Nov 2021 20:26:08 +0000 en-US hourly 1 https://wordpress.org/?v=6.4.13 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/2020/06/30/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/2020/07/15/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/2020/07/20/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/2020/08/01/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/2020/09/24/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/2020/10/09/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/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/2020/11/17/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