Assessing the inter-hemispheric transfer of symbolic numeral adaptation effect
Presented During: Poster Session 3
Friday, June 27, 2025: 01:45 PM - 03:45 PM
Friday, June 27, 2025: 01:45 PM - 03:45 PM
Presented During: Poster Session 4
Saturday, June 28, 2025: 01:45 PM - 03:45 PM
Saturday, June 28, 2025: 01:45 PM - 03:45 PM
Poster No:
2064
Submission Type:
Abstract Submission
Authors:
Ayuka Nakamura1, Junxiang Luo1, Isao Yokoi1, Hiromasa Takemura1,2,3
Institutions:
1National Institute for Physiological Sciences, Okazaki, Aichi, Japan, 2SOKENDAI, Hayama, Kanagawa, Japan, 3Core for Spin Life Sciences, Okazaki Collaborative Platform, National Institutes of Natural Sciences, Okazaki, Aichi, Japan
First Author:
Co-Author(s):
Hiromasa Takemura
National Institute for Physiological Sciences|SOKENDAI|Core for Spin Life Sciences, Okazaki Collaborative Platform, National Institutes of Natural Sciences
Okazaki, Aichi, Japan|Hayama, Kanagawa, Japan|Okazaki, Aichi, Japan
National Institute for Physiological Sciences|SOKENDAI|Core for Spin Life Sciences, Okazaki Collaborative Platform, National Institutes of Natural Sciences
Okazaki, Aichi, Japan|Hayama, Kanagawa, Japan|Okazaki, Aichi, Japan
Introduction:
Perception of symbolic numbers, such as Arabic numerals, is an essential visual function for humans. However, the exact neural mechanisms determining the subjective experience of symbolic number perception still need to be fully understood. A recent study (Luo, 2024) reported that a partial occlusion of digital numerals causes bistable perception and adaptation to symbolic numbers biased perception for partially occluded digital numerals. To further assess neural correlates of this phenomenon, testing the generalizability of adaptation between the left and right visual field is an essential approach as it reveals the involvement of mechanisms requiring interhemispheric information transfer, given the fact that the earlier visual areas predominantly respond to stimuli presented in the contralateral visual fields (Tootell, 1998; Amano, 2009). Here, we address this question by performing a psychophysical experiment that compares conditions in which adaptation and test stimuli are presented in the same or opposite visual field.
Methods:
Seventeen healthy adults (mean age 28.5; 5 males and 12 females) with normal or corrected-to-normal vision participated in this study after written informed consent. Participants were instructed to see visual stimuli presented on display (Display ++, Cambridge Research Systems) in a dark room while maintaining their fixation and head position using a chin rest. Visual stimuli were generated by using MATLAB Psychtoolbox (Brainard, 1997). Figure 1 shows the stimulus and task design of the psychophysical experiment. The experimental block began with a prolonged (30 second) adaptation to adaptation stimuli, which were digital numerals 6, 8, or control white noise, shown in either left or right visual fields. In each trial, test stimuli (Figure 1B; unmasked digital numerals or partially occluded digital numerals) were shown at either same or opposite visual fields to the adaptation stimuli. Participants were asked to report their perception of test stimuli by a button press.
We analyzed perceptual reports in trials where test stimuli were perceptually ambiguous partially occluded digital numerals. We quantified a perceptual bias in each condition by calculating the bias index, which is a difference between the proportion of trials reporting "6" and "8." We performed a paired t-test and calculated Cohen's d to assess differences in bias indexes between different adaptation conditions.
We analyzed perceptual reports in trials where test stimuli were perceptually ambiguous partially occluded digital numerals. We quantified a perceptual bias in each condition by calculating the bias index, which is a difference between the proportion of trials reporting "6" and "8." We performed a paired t-test and calculated Cohen's d to assess differences in bias indexes between different adaptation conditions.
Results:
Figure 2A depicts the results of the condition in which adaptation and test stimuli were presented in the same (left or right) visual field. We replicated the initial finding by Luo et al. (2024), showing that adaptation to 6 induces perceptual bias to 8, whereas adaptation to 8 induces perceptual bias to 6. The population results shown in the violin plot (Figure 2A, right panel) indicate that perceptual reports were significantly affected by a type of adaptation stimuli (d = -1.65; p = 0.0003). Importantly, we found that the same effect was also observed when test stimuli were presented in the opposite visual field from that of adaptation stimuli (Figure 2B). Results showed statistically significant perceptual bias depending on adaptation stimuli, while effect size becomes smaller (d = -0.82; p = 0.0005).
Conclusions:
These results suggest an involvement of visual mechanisms after the integration of information between left and right visual fields to the symbolic numeral adaptation effects. Our findings are essential for designing future neuroimaging experiments to evaluate neural correlates of number perception by measuring functional response to the bistable perception of symbolic numerals or evaluating the relationship with tissue properties of the callosal white matter pathway connecting two hemispheres.
Higher Cognitive Functions:
Space, Time and Number Coding 2
Perception, Attention and Motor Behavior:
Perception: Visual 1
Keywords:
Cognition
Perception
Vision
Other - Psychophysics
1|2Indicates the priority used for review
Abstract Information
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Provide references using APA citation style.
Brainard, D. H. (1997). The Psychophysics Toolbox. Spatial Vision, 10, 433–436.
Luo, J. (2024). Bistable perception of symbolic numbers. Journal of Vision, 24(9), 12.
Tootell, R.B.H. (1998). The representation of the ipsilateral visual field in human cerebral cortex. Proc. Natl. Acad. Sci. U.S.A., 95 (3), 818-824.