https://www.pisavisionlab.org Research centre dedicated to frontier, interdisciplinary research of human perception Fri, 04 Oct 2024 08:11:20 +0000 en-US hourly 1 https://wordpress.org/?v=6.4.13 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/2024/09/06/pupillometry-indexes-ocular-dominance-plasticity/ Fri, 06 Sep 2024 13:06:16 +0000 https://www.pisavisionlab.org/?p=4931 Vision Research, Volume 222, 2024, 108449, ISSN 0042-6989 Short-term monocular deprivation in normally sighted adult humans produces a transient shift of ocular dominance, boosting the deprived eye. This effect has been documented with both perceptual tests and through physiological recordings, but no previous study simultaneously measured physiological responses and the perceptual effects of deprivation. Here we propose an integrated experimental paradigm that combines binocular rivalry with pupillometry, to introduce an objective physiological index of ocular dominance plasticity, acquired concurrently with perceptual testing. Ten participants reported the perceptual dynamics of binocular rivalry, while we measured pupil diameter. Stimuli were a white and a black disk, each presented monocularly. Rivalry dynamics and pupil-size traces were compared before and after 2 h of monocular deprivation, achieved by applying a translucent patch over the dominant eye. Consistent with prior research, we observed that monocular deprivation boosts the deprived-eye signal and consequently increases ocular dominance. In line with previous studies, we also observed subtle but systematic modulations of pupil size that tracked alternations between exclusive dominance phases of the black or white disk. Following monocular deprivation, the amplitude of these pupil-size modulations increased, which is consistent with the post-deprivation boost of the deprived eye and the increase of ocular dominance. This provides evidence that deprivation impacts the effective strength of monocular visual stimuli, coherently affecting perceptual reports and the automatic and unconscious regulation of pupil diameter. Our results show that a combined paradigm of binocular rivalry and pupillometry gives new insights into the physiological mechanisms underlying deprivation effects. Miriam Acquafredda, Paola Binda https://www.pisavisionlab.org/2024/09/06/pupillometry-indexes-ocular-dominance-plasticity/pupillometry-indexes-ocular-dominance-plasticity/https://doi.org/10.1016/j.visres.2024.108449 https://www.pisavisionlab.org/2024/09/09/correlated-p300b-and-phasic-pupil-dilation-responses-to-motivationally-significant-stimuli/ Mon, 09 Sep 2024 09:19:22 +0000 https://www.pisavisionlab.org/?p=4961 Psychophysiology, 61, e14550 Motivationally significant events like oddball stimuli elicit both a characteristic event-related potential (ERPs) known as P300 and a set of autonomic responses including a phasic pupil dilation. Although co-occurring, P300 and pupil-dilation responses to oddball events have been repeatedly found to be uncorrelated, suggesting separate origins. We re-examined their relationship in the context of a three-stimulus version of the auditory oddball task, independently manipulating the frequency (rare vs. repeated) and motivational significance (relevance for the participant's task) of the stimuli. We used independent component analysis to derive a P300b component from EEG traces and linear modeling to separate a stimulus-related pupil-dilation response from a potentially confounding action-related response. These steps revealed that, once the complexity of ERP and pupil-dilation responses to oddball targets is accounted for, the amplitude of phasic pupil dilations and P300b are tightly and positively correlated (across participants: r = .69 p = .002), supporting their coordinated generation. D. Menicucci, S. Animali, E. Malloggi,A. Gemignani, E. Bonanni, F. Fornai, F. Sean Giorgi, P. Binda https://www.pisavisionlab.org/2024/09/09/correlated-p300b-and-phasic-pupil-dilation-responses-to-motivationally-significant-stimuli/psychophysiology-2024-menicucci-correlated-p300b-and-phasic-pupil%e2%80%90dilation-responses-to-motivationally-significant/ https://doi.org/10.1111/psyp.14550