https://www.pisavisionlab.org Research centre dedicated to frontier, interdisciplinary research of human perception Fri, 12 Jun 2026 08:29:45 +0000 en-US hourly 1 https://wordpress.org/?v=6.4.10 https://www.pisavisionlab.org/2023/11/19/action-shaped-perception-towards-a-reunification-of-two-systems/ Sun, 19 Nov 2023 11:38:17 +0000 https://www.pisavisionlab.org/?p=4783 PhD Thesis In this dissertation I investigated the relationship between action and perception in the processing of Space, Time and Numerosity. In the first chapter the most prominent literature on the topic is reviewed to introduce the conceptual framework in which the experimental paradigms were developed. In 2003 Vincent Walsh proposed A Theory of Magnitude (ATOM) which posits that space, time and numerosity share a common processing mechanism rooted in our need for information about the spatial and temporal structure of the external world. According to Walsh, we could learn about the association between the fundamental magnitudes through our interaction with the environment, as in real-life settings they often correlate with each other (for instance, a higher number of items takes up a larger space and requires a longer time to be retrieved). One of the functional consequences of the ATOM theory would be a perceptual interference across magnitudes, which would result in judgments regarding one magnitude being biased by another irrelevant one. In the second chapter of this thesis, I demonstrate that the interaction between duration and numerosity is task-dependent: participants’ judgments about stimulus duration were influenced by stimulus numerosity only when tested with a discrimination task. This suggests that the cross-magnitude interaction predicted by the ATOM Theory does not occur at the processing level, but it is dependent by the kind of task (ie. comparisons) the observer is required to perform. This, in turn, suggests that the interplay between time and numerosity occurs at a later stage after perceptual processing as for example, at the decisional level. In chapter 3 I report evidence for 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. As the influence of tapping on numerosity and duration perception had been previously demonstrated, these results offer clear evidence for a generalized interaction between the motor system and the processing of perceptual magnitude information in line with the ATOM Theory predictions (see above). After demonstrating the influence of upper-body movements on magnitude perception, Chapter 4 is dedicated to the investigation of the influence of lower-body movements on the perception of duration and numerosity. As already reported in previous literature, I found that running systematically interferes with duration perception as it causes an overestimation of perceived time. However, in order to overcome some of the discrepancies in the existing literature that might be caused by methodological differences, I applied a standardized motor paradigm to different time ranges and sensory modalities. This allowed me to generalize the effect induced by running on duration perception across visual and auditory modalities and across sub-second and supra-second duration ranges. On the other hand, I found no distortion of numerosity judgments because of running, suggesting that this effect does not generalize across magnitudes. Lastly, I focused on the importance of Peripersonal (PPS) and Extrapersonal (EPS) space in the investigation of the relationship between action and perception, which is often overlooked, but remains a vital component in the theoretical framework of ATOM theory. Indeed, action needs proximity with its target, and there is evidence of perceptual networks dedicated exclusively to PPS. As is often the case with magnitude perception, time has been the first domain investigated while taking into account the influence of stimulus distance. One of the research lines carried out during the PhD was aimed at generalizing the effects of PPS and EPS on time to numerosity perception. My results clearly indicate numerosity perception relies less on stimulus distance than time does, with participants showing the same perceptual precision and accuracy in both EPS and PPS. In the last chapter I applied the psychophysical methodologies I got familiar to during the PHD to study perception in a virtual reality (VR) environment that allow to test perceptual processes in highly ecological settings to make VR always more important in future research of perceptual neuroscience. This study was conducted in collaboration with the Center for Applied Neuroscience of the University of Cyprus where I spent 7 months during my period abroad. My aim was to validate in VR a paradigm that has been replicated multiple times in real world settings to measure the size of participants’ PPS. Following this, I also experimented a tool-training method aimed at reshaping participants’ PPS. My results show that, similarly to real world settings, a short period of tool-training is sufficient to cause a significant enlargement of the PPS. This result is of primary importance, as it shows for the first time that PPS in Virtual Reality has similar characteristics of Peripersonal space as measured in real life settings, thus offering evidence towards a valuable validation of VR as a tool to study the characteristics of Peripersonal space. Irene Petrizzo https://www.pisavisionlab.org/2023/11/19/action-shaped-perception-towards-a-reunification-of-two-systems/phdthesis_petrizzo/https://hdl.handle.net/2158/1321552 https://www.pisavisionlab.org/2023/11/19/similar-effect-of-running-on-visual-and-auditory-time-perception-in-the-ranges-of-milliseconds-and-seconds/ Sun, 19 Nov 2023 13:45:52 +0000 https://www.pisavisionlab.org/?p=4787 Frontiers in Psychology Introduction: The ability to accurately encode events’ duration is of critical importance for almost all everyday activities, yet numerous factors have been reported to robustly distort time perception. One of these is physical activity (i.e., running, walking) but, partly due to the variety of methodologies employed, a full comprehension of the role of exercise on the encoding of time has still to be achieved. Methods: Here we tackle the issue with a multifaceted approach by measuring the effect of vigorous running with a time generalization task for visual and auditory stimuli in the range of milliseconds (0.2–0.8 s) as well as seconds (1–4 s). At baseline, participants performed both the encoding and decoding at rest while in the experimental conditions the decoding was performed while running. Results: Our results indicate that physical activity in both duration ranges (sub-second and seconds) was expanded during running regardless of the sensory modality used to present the stimuli. Despite this generalized effect of running on perceived duration, we found evidence for the existence of independent timing mechanisms: (1) the perceptual biases induced by running in the two temporal regimes were uncorrelated, (2) sensory precision levels (Weber fraction) were higher for stimuli in the seconds range, (3) sensory precision levels were higher for auditory than for visual stimuli, but only within the sub-second range. Discussion: Overall, our results support previous findings suggesting (at least partially) separate timing mechanisms for short/long durations and for visual and auditory stimuli. However, they also indicate that physical activity affects all these temporal modules, suggesting a generalized interaction—via generalized and shared resources—between the motor system and the brain time mechanisms. Irene Petrizzo, Eleonora Chelli, Tommaso Bartolini, Roberto Arrighi, Giovanni Anobile https://www.pisavisionlab.org/2023/11/19/similar-effect-of-running-on-visual-and-auditory-time-perception-in-the-ranges-of-milliseconds-and-seconds/fpsyg-14-1146675-1/https://doi.org/10.3389/fpsyg.2023.1146675 https://www.pisavisionlab.org/2023/11/19/reshaping-the-peripersonal-space-in-virtual-reality/ Sun, 19 Nov 2023 15:15:02 +0000 https://www.pisavisionlab.org/?p=4791 Scientific Reports (under review) Peripersonal space (PPS) refers to the space around us that lies within reach, in which most of our interactions with the environment occur. However, the PPS is not a static bubble surrounding our body. Rather, it can be dynamically reshaped in size, for instance as a consequence of the use of tools extending the arm’s reach. Here we employed a visuo-tactile detection task in an immersive VR environment to measure the size of participants’ PPS before and after different kinds of tool training. A short training period in which participants pulled objects from the Extrapersonal space (EPS) towards themselves via a tool was effective in enlarging the PPS, a result that nicely complements previous studies carried out in real life studies. However, no signicant change in PPS size was achieved via training with other motor routines such as pulling, hammering or shooting, each of which involving a different kind of interaction between the agent and the targets. Taken together, our results suggest that the reshaping of the PPS is a complex phenomenon in which the kind of motor routines exploited to interact with the surrounding objects, plays a critical role. Irene Petrizzo, Kyriaki Mikellidou, Savvas Avraam, Marios Avraamides and Roberto Arrighi https://www.pisavisionlab.org/2023/11/19/reshaping-the-peripersonal-space-in-virtual-reality/dc33a18f-ab8c-464b-814d-1d05893af17a/https://doi.org/10.21203/rs.3.rs-3101264/v1 https://www.pisavisionlab.org/2023/11/19/sensorimotor-mechanisms-selective-to-numerosity-evidence-from-individual-differences/ Sun, 19 Nov 2023 15:21:08 +0000 https://www.pisavisionlab.org/?p=4795 eLife We have previously shown that after few seconds of adaptation by finger-tapping, the perceived numerosity of spatial arrays and temporal sequences of visual objects displayed near the tapping region is increased or decreased, implying the existence of a sensorimotor numerosity system (Anobile et al., 2016). To date, this mechanism has been evidenced only by adaptation. Here, we extend our finding by leveraging on a well-established covariance technique, used to unveil and characterize ‘channels’ for basic visual features such as colour, motion, contrast, and spatial frequency. Participants were required to press rapidly a key a specific number of times, without counting. We then correlated the precision of reproduction for various target number presses between participants. The results showed high positive correlations for nearby target numbers, scaling down with numerical distance, implying tuning selectivity. Factor analysis identified two factors, one for low and the other for higher numbers. Principal component analysis revealed two bell-shaped covariance channels, peaking at different numerical values. Two control experiments ruled out the role of non-numerical strategies based on tapping frequency and response duration. These results reinforce our previous reports based on adaptation, and further suggest the existence of at least two sensorimotor number channels responsible for translating symbolic numbers into action sequences. Giovanni Anobile, Irene Petrizzo, Daisy Paiardini, David Burr, Guido Marco Cicchini https://www.pisavisionlab.org/2023/11/19/sensorimotor-mechanisms-selective-to-numerosity-evidence-from-individual-differences/elife-92169-v1/https://doi.org/10.7554/eLife.92169.3 https://www.pisavisionlab.org/2023/12/21/drivers-performance-assessment-approaching-pedestrian-crossings-through-the-analysis-of-the-speed-and-perceptive-data-recorded-during-on-field-tests/ Thu, 21 Dec 2023 11:49:47 +0000 https://www.pisavisionlab.org/?p=4845 Heliyon (in press) Pedestrian fatalities in road accidents represent one of the biggest causes of death in the world despite the great efforts that have been made to decrease the involvement of vulnerable road users in road accidents. Literature analysis revealed the presence of several studies aimed at investigating the phenomenon and proposing strategies to improve pedestrian safety, but this is still not enough to considerably reduce the number of pedestrians killed on the road. In this context, with the aim to take a step forward in the topic, this paper describes a naturalistic driving assessment carried out in Firenze aimed at evaluating the effect of different pedestrian crossing configurations on the drivers’ behavior, especially concerning the reduction of the speeding phenomenon approaching a pedestrian crossing. The experiment was conducted on a section of an urban collector road within the Firenze suburban area. Crucially, over the past few years, different traffic calming interventions have been implemented along this street. Among the different traffic calming countermeasures, both the presence of a traffic light and trapezoidal deflection have been considered to assess their effect on drivers’ behavior, also with reference to specific aspects related to the drivers’ perception. During the experiment, thirty-six users drove their own vehicles along the street, encountering different pedestrian crossing configurations. During the driving speed, deceleration and ocular fixation were recorded. This study shows the difference in drivers’ behavior in response to different traffic calming countermeasures. It demonstrates also that the raised pedestrian crossing caused a significant effect on reducing the speed approaching a pedestrian crossing. Moreover, it is observed that, when perceptive countermeasures are present, the drivers’ behavior changes only if the pedestrian crossing configuration is perceived in foveal vision; suggesting that the correct identification of the configuration is crucial to implement a congruent and safe driving behavior. Meocci, M., Terrosi, A., Paliotto, A., Arrighi, R. & Petrizzo, I.