https://www.pisavisionlab.org Research centre dedicated to frontier, interdisciplinary research of human perception Thu, 10 Sep 2026 08:48:13 +0000 en-US hourly 1 https://wordpress.org/?v=6.4.13 https://www.pisavisionlab.org/2024/04/08/investigating-cross-orientation-inhibition-with-continuous-tracking/ Mon, 08 Apr 2024 14:38:08 +0000 https://www.pisavisionlab.org/?p=4866 Journal of Vision 24 We investigated cross-orientation inhibition with the recently developed continuous tracking technique. We designed an experiment where participants tracked the horizontal motion of a narrow vertical grating. The target was superimposed on one of three different backgrounds, in separate sessions: a uniform gray background or a sinusoidal grating oriented either parallel or orthogonal to the target. Both mask and target where phase reversed. We cross-correlated target and mouse movements and compared the peaks and lags of response with the different masks. Our results are in agreement with previous findings on cross-orientation inhibition: The orthogonal mask had a weak effect on the peaks and lags of correlation as a function of target contrast, consistently with a divisive effect of the mask, while the parallel mask acted subtractively on the response. Interestingly, lags of correlation decreased approximately linearly with contrast, with decrements of the order of 100 ms, even at 10 times the detection threshold, confirming that it is possible to investigate behavioral differences above threshold using the continuous tracking paradigm. Ambrosi, Pierfrancesco, David Charles Burr, e Maria Concetta Morrone https://www.pisavisionlab.org/2024/04/08/investigating-cross-orientation-inhibition-with-continuous-tracking/i1534-7362-24-2-2_1706704546-25472/https://doi.org/10.1167/jov.24.2.2 https://www.pisavisionlab.org/2024/04/08/disambiguating-vision-with-sound/ Mon, 08 Apr 2024 14:42:19 +0000 https://www.pisavisionlab.org/?p=4869 Current Biology, 34(6), R235–R236 An important task for the visual system is to identify and segregate objects from background. Figure–ground illusions, such as Edgar Rubin’s bistable ‘vase–faces illusion’1, make the point clearly: we see either a central vase or lateral faces, alternating spontaneously, but never both images simultaneously. The border is perceptually assigned to either faces or vase, which become figure, the other shapeless background2. The stochastic alternation between figure and ground probably reflects mutual inhibitory processes that ensure a single perceptual outcome3. Which shape dominates perception depends on many factors, such as size, symmetry, convexity, enclosure, and so on, as well as attention and intention4. Here we show that the assignment of the visual border can be strongly influenced by auditory input, far more than is possible by voluntary intention. Gori, M., Burr, D., & Campus, C. https://www.pisavisionlab.org/2024/04/08/disambiguating-vision-with-sound/1-s2-0-s0960982224000782-main/https://doi.org/10.1016/j.cub.2024.01.043 https://www.pisavisionlab.org/2024/04/08/adaptation-to-numerosity-affects-the-pupillary-light-response/ Mon, 08 Apr 2024 15:19:01 +0000 https://www.pisavisionlab.org/?p=4878 Sci Rep 14, 6097 (2024) We recently showed that the gain of the pupillary light response depends on numerosity, with weaker responses to fewer items. Here we show that this effect holds when the stimuli are physically identical but are perceived as less numerous due to numerosity adaptation. Twenty-eight participants adapted to low (10 dots) or high (160 dots) numerosities and subsequently watched arrays of 10–40 dots, with variable or homogeneous dot size. Luminance was constant across all stimuli. Pupil size was measured with passive viewing, and the effects of adaptation were checked in a separate psychophysical session. We found that perceived numerosity was systematically lower, and pupillary light responses correspondingly smaller, following adaptation to high rather than low numerosities. This is consistent with numerosity being a primary visual feature, spontaneously encoded even when task irrelevant, and affecting automatic and unconscious behaviours like the pupillary light response. C.Caponi, E. Castaldi, D.C. Burr, P. Binda https://www.pisavisionlab.org/2024/04/08/adaptation-to-numerosity-affects-the-pupillary-light-response/s41598-024-55646-w/https://doi.org/10.1038/s41598-024-55646-w https://www.pisavisionlab.org/2024/09/03/neural-substrates-for-early-data-reduction-in-fast-vision-a-psychophysical-investigation/ Tue, 03 Sep 2024 09:39:03 +0000 https://www.pisavisionlab.org/?p=4923 Brain Sciences To ensure survival, the visual system must rapidly extract the most important elements from a large stream of information. This necessity clashes with the computational limitations of the human brain, so a strong early data reduction is required to efficiently process information in fast vision. A theoretical early vision model, recently developed to preserve maximum information using minimal computational resources, allows efficient image data reduction by extracting simplified sketches containing only optimally informative, salient features. Here, we investigate the neural substrates of this mechanism for optimal encoding of information, possibly located in early visual structures. We adopted a flicker adaptation paradigm, which has been demonstrated to specifically impair the contrast sensitivity of the magnocellular pathway. We compared flicker-induced contrast threshold changes in three different tasks. The results indicate that, after adapting to a uniform flickering field, thresholds for image discrimination using briefly presented sketches increase. Similar threshold elevations occur for motion discrimination, a task typically targeting the magnocellular system. Instead, contrast thresholds for orientation discrimination, a task typically targeting the parvocellular system, do not change with flicker adaptation. The computation performed by this early data reduction mechanism seems thus consistent with magnocellular processing. Serena Castellotti & Maria Michela Del Viva https://www.pisavisionlab.org/2024/09/03/neural-substrates-for-early-data-reduction-in-fast-vision-a-psychophysical-investigation/castellotti2024_flicker/https://doi.org/ 10.3390/brainsci14080753 https://www.pisavisionlab.org/2024/09/07/the-role-of-motor-effort-on-the-sensorimotor-number-system/ Sat, 07 Sep 2024 13:13:24 +0000 https://www.pisavisionlab.org/?p=4935 Psychological Research The integration of numerical information with motor processes has emerged as a fascinating area of investigation in both animal and human cognition. The interest in a sensorimotor number system has recently generated neurophysiological and psychophysical evidence which combine to highlight the importance of motor functions in the encoding of numerical information. Nevertheless, several key questions remain, such as the influence of non-numerical motor parameters over numerical perception. Here we tested the role of physical effort, a parameter positively correlated with the number of actions, in modulating the link between hand-actions and visual numerosity perception. Effort was manipulated during sensorimotor adaptation as well as during a new actions-estimation paradigm. The results of Experiment 1 shows that physical effort in the absence of actions (passive effort) is not sufficient to activate the sensorimotor number system, indicating that self-produced actions are instead necessary. Further experiments demonstrated that effort is marginally integrated during motor adaptation (Experiment 2) but discarded when estimating the number of self-produced hand actions (Experiment 3). Overall, the results indicate that the sensorimotor number system is largely fed by the number of discrete actions rather than the amount of effort but also indicates that effort (under specific circumstances) might be integrated. These findings provide novel insights into the sensorimotor numerical integration, paving the way for future investigations, such as on its functional role. Benedetto, A., Chelli, E., Petrizzo, I., Arrighi, R., & Anobile, G. https://www.pisavisionlab.org/2024/09/07/the-role-of-motor-effort-on-the-sensorimotor-number-system/s00426-024-02002-2/https://doi.org/10.1007/s00426-024-02002-2 https://www.pisavisionlab.org/2024/09/07/neurocognitive-assessment-of-mathematics-related-capacities-in-neurosurgical-patients/ Sat, 07 Sep 2024 13:18:07 +0000 https://www.pisavisionlab.org/?p=4938 Brain Sciences, 14(1) A precise neuropsychological assessment is of the utmost importance for neurosurgical patients undergoing the surgical excision of cerebral lesions. The assessment of mathematical abilities is usually limited to arithmetical operations while other fundamental visuo-spatial aspects closely linked to mathematics proficiency, such as the perception of numerical quantities and geometrical reasoning, are completely neglected. We evaluated these abilities with two objective and reproducible psychophysical tests, measuring numerosity perception and non-symbolic geometry, respectively. We tested sixteen neuro-oncological patients before the operation and six after the operation with classical neuropsychological tests and with two psychophysical tests. The scores of the classical neuropsychological tests were very heterogeneous, possibly due to the distinct location and histology of the tumors that might have spared (or not) brain areas subserving these abilities or allowed for plastic reorganization. Performance in the two non-symbolic tests reflected, on average, the presumed functional role of the lesioned areas, with participants with parietal and frontal lesions performing worse on these tests than patients with occipital and temporal lesions. Single-case analyses not only revealed some interesting exceptions to the group-level results (e.g., patients with parietal lesions performing well in the numerosity test), but also indicated that performance in the two tests was independent of non-verbal reasoning and visuo-spatial working memory. Our results highlight the importance of assessing non-symbolic numerical and geometrical abilities to complement typical neuropsychological batteries. However, they also suggest an avoidance of reliance on an excessively rigid localizationist approach when evaluating the neuropsychological profile of oncological patients. Castaldi, E., Bonaudo, C., Maduli, G., Anobile, G., Pedone, A., Capelli, F., Arrighi, R., & Della Puppa, A https://www.pisavisionlab.org/2024/09/07/neurocognitive-assessment-of-mathematics-related-capacities-in-neurosurgical-patients/brainsci-14-00069/https://doi.org/10.3390/brainsci14010069 https://www.pisavisionlab.org/2024/09/07/auditory-time-perception-impairment-in-children-with-developmental-dyscalculia/ Sat, 07 Sep 2024 13:20:51 +0000 https://www.pisavisionlab.org/?p=4941 Research in Developmental Disabilities, 149, 104733 Developmental dyscalculia (DD) is a specific learning disability which prevents children from acquiring adequate numerical and arithmetical competences. We investigated whether difficulties in children with DD spread beyond the numerical domain and impact also their ability to perceive time. A group of 37 children/adolescent with and without DD were tested with an auditory categorization task measuring time perception thresholds in the sub-second (0.25–1 s) and supra-second (0.75–3 s) ranges. Results showed that auditory time perception was strongly impaired in children with DD at both time scales. The impairment remained even when age, non-verbal reasoning, and gender were regressed out. Overall, our results show that the difficulties of DD can affect magnitudes other than numerical and contribute to the increasing evidence that frames dyscalculia as a disorder affecting multiple neurocognitive and perceptual systems. Castaldi, E., Tinelli, F., Filippo, G., Bartoli, M., & Anobile, G. https://www.pisavisionlab.org/2024/09/07/auditory-time-perception-impairment-in-children-with-developmental-dyscalculia/1-s2-0-s0891422224000659-main/https://doi.org/10.1016/j.ridd.2024.104733 https://www.pisavisionlab.org/2024/09/07/serial-dependence-in-perception/ Sat, 07 Sep 2024 13:24:51 +0000 https://www.pisavisionlab.org/?p=4944 Annual Review of Psychology Much evidence has shown that perception is biased towards previously presented similar stimuli, an effect recently termed serial dependence. Serial dependence affects nearly every aspect of perception, often causing gross perceptual distortions, especially for weak and ambiguous stimuli. Despite unwanted side-effects, empirical evidence and Bayesian modeling show that serial dependence acts to improve efficiency and is generally beneficial to the system. Consistent with models of predictive coding, the Bayesian priors of serial dependence are generated at high levels of cortical analysis, incorporating much perceptual experience, but feed back to lower sensory areas. These feedback loops may drive oscillations in the alpha range, linked strongly with serial dependence. The discovery of top-down predictive perceptual processes is not new, but the new, more quantitative approach characterizing serial dependence promises to lead to a deeper understanding of predictive perceptual processes and their underlying neural mechanisms. Cicchini, G. M., Mikellidou, K., & Burr, D. C. https://www.pisavisionlab.org/2024/09/07/serial-dependence-in-perception/annurev-psych-021523-104939/https://doi.org/10.1146/annurev-psych-021523-104939 https://www.pisavisionlab.org/2024/09/07/electrophysiological-correlates-of-temporal-numerosity-adaptation/ Sat, 07 Sep 2024 13:29:47 +0000 https://www.pisavisionlab.org/?p=4948 Front. Neurosci. Introduction: Much research has revealed the human visual system is capable to estimate numerical quantities, rapidly and reliably, in both the spatial and the temporal domain. This ability is highly susceptible to short-term plastic phenomena related to previous exposure to visual numerical information (i.e., adaptation). However, while determinants of spatial numerosity adaptation have been widely investigated, little is known about the neural underpinnings of short-term plastic phenomena related to the encoding of temporal numerical information. In the present study we investigated the electrophysiological correlates of temporal numerosity adaptation. Methods: Participants were asked to estimate the numerosity of a test sequence of flashes after being exposed to either a high or low numerous adapting sequence. Behavioral results confirmed the expected underestimation of test stimulus when this was preceded by a high numerous sequence as compared to when preceded by a low numerous sequence. Results: Electrophysiological data revealed that this behavior was tightly linked to the amplitude of the steady-state visual evoked (ssVEP) response elicited by the test stimulus. When preceded by a high numerous sequence, the test stimulus elicited larger ssVEP responses as compared to when preceded by a low numerous sequence with this pattern being robustly correlated with behavior. Finally, topographical maps showed that this difference was mostly evident across two antero-posterior distributed clusters of electrodes and correlated with changes in functional connectivity. Discussion: Taken together, our results suggest that visual plastic phenomena related to the encoding of temporal numerosity information reflect changes in rhythmic evoked activity that are likely related to long range communications between distinct brain regions. Grasso, P. A., Petrizzo, I., Coniglio, F., & Arrighi, R. https://www.pisavisionlab.org/2024/09/07/electrophysiological-correlates-of-temporal-numerosity-adaptation/fnins-18-1349540/https://doi.org/10.3389/fnins.2024.1349540 https://www.pisavisionlab.org/2024/09/07/reshaping-the-peripersonal-space-in-virtual-reality-2/ Sat, 07 Sep 2024 13:32:25 +0000 https://www.pisavisionlab.org/?p=4951 Scientific reports Peripersonal space (PPS) is defined as the space that lies within reach. Previous research revealed that PPS can be dynamically reshaped with the use of tools extending the arm’s reach. Here we investigated whether PPS reshaping depends on the kind of selected tool and/or the motor routine associated with its use. Participants carried out a visuo-tactile detection task in an immersive VR environment that allowed to measure the PPS size before and after a short period of tools use. In Experiment 1, participants had to pull or push objects towards or away from themselves using a shovel. In Experiment 2, they were required to either hammer or shoot an avatar placed in the Extrapersonal space. We found, for the first time in a VR environment, that a period of pull training was effective in enlarging the PPS, a result that replicates and expands previous findings carried out in real life conditions. However, no significant change in PPS size was achieved for training with other tools and motor routines. Our results suggest that the reshaping of PPS is a complex phenomenon in which the kind of interaction between the agent, the targets and the exploited motor routines all play a critical role. Petrizzo, I., Mikellidou, K., Avraam, S., Avraamides, M., & Arrighi, R. https://www.pisavisionlab.org/2024/09/07/reshaping-the-peripersonal-space-in-virtual-reality-2/s41598-024-52383-y/https://doi.org/10.1038/s41598-024-52383-y https://www.pisavisionlab.org/2024/09/07/what-pupil-size-can-and-cannot-tell-about-math-anxiety/ Sat, 07 Sep 2024 13:35:14 +0000 https://www.pisavisionlab.org/?p=4954 Psychological Research Math Anxiety (MA) consists of excessive fear and worry about math-related situations. It represents a major barrier to numerical competence and the pursuit of STEM careers. Yet, we currently do not dispose of many tools that can capture its multifaceted nature, e.g. moving beyond the exclusive reliance on self-reports and meta-cognition. Here we sought to probe Pupil Size (PS) as a viable tool in the study of MA by administering arithmetic problems to university students in the humanities (N = 70) with various levels of MA. We found that arithmetic competence and performance are indeed negatively associated with MA, and this is accurately tracked by PS. When performance is accounted for, MA does not further modulate PS (before, during, or after calculation). However, the latency of PS peak dilation can add a significant contribution to predicting MA scores, indicating that high MA may be accompanied by more prolonged cognitive effort. Results show that MA and mathematical competence may be too crystalized in young university students to be discernible. We therefore call for early educational interventions to tackle and mitigate this dysfunctional association early on. Blini, E., Anobile, G., & Arrighi, R. https://www.pisavisionlab.org/2024/09/07/what-pupil-size-can-and-cannot-tell-about-math-anxiety/s00426-024-02020-0/https://doi.org/10.1007/s00426-024-02020-0 https://www.pisavisionlab.org/2024/09/07/number-adaptation-reply/ Sat, 07 Sep 2024 13:39:52 +0000 https://www.pisavisionlab.org/?p=4957 SSRN Scholarly Paper 4839798 Adaptation is a ubiquitous property of perceptual systems, allowing them to operate over a large dynamic range, and increasing sensitivity to change. The number sense, like most other perceptual systems, shows strong adaptation. In this issue, Yousef et al challenge the existence of number adaptation, offering an alternate explanation that they term the “old news hypothesis”. Here we consider the major evidence advanced for their theory and show that, while their predicted effects may reach statistical significance, they are far too small to begin to explain the robust phenomenon of adaptation. We also highlight a series of studies using fMRI, EEG, pupillometry and psycho­physical techniques that support the existence of adaption, and are inconsistent with “old news”. We conclude that number adaptation, while not entirely understood, remains an invaluable concept for understanding the number sense. Burr, D. C., Anobile, G., & Arrighi, R. https://www.pisavisionlab.org/2024/09/07/number-adaptation-reply/ssrn-4839798-2/https://doi.org/10.2139/ssrn.4839798 https://www.pisavisionlab.org/2024/10/23/positive-serial-dependence-in-ratings-of-food-images-for-appeal-and-calories/ Wed, 23 Oct 2024 18:58:25 +0000 https://www.pisavisionlab.org/?p=4994 Current Biology Food is fundamental to survival, and our brains are highly attuned to rapidly process food stimuli. Neural signals show that foods can be discriminated as edible or inedible as early as 85 ms after stimulus onset,1 distinguished as processed or unprocessed beginning at 130 ms,2 and as high or low density from 165 ms.3 Recent evidence revealed specialized processing of food stimuli in the ventral visual pathway,4,5,6 an area that underlies perception of faces and other important objects. For many visual objects, perception can be biased toward recent perceptual history (known as serial dependence7,8). We examined serial dependence for food in two large samples (n > 300) who rated sequences of food images for either “appeal” or “calories.” Ratings for calories were highly correlated between participants and were similar for males and females. Appeal ratings varied considerably between participants, consistent with the idiosyncratic nature of food preferences, and tended to be higher for males than females. High-calorie ratings were associated with high appeal, especially in males. Importantly, response biases showed clear positive serial dependences: higher stimulus values in the previous trials led to positive biases, and vice versa. The effects were similar for males and females and for calories and appeal ratings and were remarkably consistent across participants. These findings square with recently found food selectively in the visual temporal cortex, reveal a new mechanism influencing food decision-making, and suggest a new sensory-level component that could complement cognitive strategies in diet intervention. Alais, D., Burr, D., & Carlson, T. A. https://www.pisavisionlab.org/2024/10/23/positive-serial-dependence-in-ratings-of-food-images-for-appeal-and-calories/piis0960982224012235/https://doi.org/10.1016/j.cub.2024.09.012 https://www.pisavisionlab.org/2025/09/01/color-crowding-considered-as-adaptive-spatial-integration/ Mon, 01 Sep 2025 10:14:18 +0000 https://www.pisavisionlab.org/?p=5187 Journal of Vision, 24(13), 9 Crowding is the inability to recognize an object in clutter, classically considered a fundamental low-level bottleneck to object recognition. Recently, however, it has been suggested that crowding, like predictive phenomena such as serial dependence, may result from optimizing strategies that exploit redundancies in natural scenes. This notion leads to several testable predictions, such as crowding being greater for nonsalient targets and, counterintuitively, that flanker interference should be associated with higher precision in judgements, leading to a lower overall error rate. Here we measured color discrimination for targets flanked by stimuli of variable color. The results verified both predictions, showing that although crowding can affect object recognition, it may be better understood not as a processing bottleneck, but rather as a consequence of mechanisms evolved to efficiently exploit the spatial redundancies of the natural world. Analyses of reaction times of judgments shows that the integration occurs at sensory rather than decisional levels. Cicchini, G. M., D’Errico, G., & Burr, D. C. https://www.pisavisionlab.org/2025/09/01/color-crowding-considered-as-adaptive-spatial-integration/i1534-7362-24-13-9_1733745989-28729/https://doi.org/10.1167/jov.24.13.9 https://www.pisavisionlab.org/2026/09/10/development-of-higher-level-vision-a-network-perspective/ Thu, 10 Sep 2026 08:48:12 +0000 https://www.pisavisionlab.org/?p=5434 The Journal of Neuroscience Most studies on the development of the visual system have focused on the mechanisms shaping early visual stages up to the level of primary visual cortex (V1). Much less is known about the development of the stages after V1 that handle the higher visual functions fundamental to everyday life. The standard model for the maturation of these areas is that it occurs sequentially, according to the positions of areas in the adult hierarchy. Yet, the existing literature reviewed here paints a different picture, one in which the adult configuration emerges through a sequence of unique network configurations that are not mere partial versions of the adult hierarchy. In addition to studying higher visual development per se to fill major gaps in knowledge, it will be crucial to adopt a network-level perspective in future investigations to unravel normal developmental mechanisms, identify vulnerabilities to developmental disorders, and eventually devise treatments for these disorders. James A. Bourne, Radoslaw M. Cichy, Lynne Kiorpes, Maria Concetta Morrone, Michael J. Arcaro and Kristina J. Nielsen https://www.pisavisionlab.org/2026/09/10/development-of-higher-level-vision-a-network-perspective/e1291242024-full/https://doi.org/10.1523/JNEUROSCI.1291-24.2024