A bias in saccadic suppression of shape change

Area of Science:

• Neuroscience
• Cognitive Science
• Visual Perception

Background:

• Visual information processing significantly differs between the central (foveal) and peripheral visual fields.
• The visual system must compensate for these processing disparities to maintain a stable perception of the visual world during eye movements (saccades).

Purpose of the Study:

• To investigate how differences in visual field processing influence transsaccadic perception of shape changes.
• To test the hypothesis that visual field disparities and learned expectations impact the perception of shape morphing across saccades.

Main Methods:

• Participants performed a change-discrimination task involving morphed shapes (triangle to circle) presented across saccades.
• Shape perception was analyzed under conditions where stimuli were presented exclusively in the periphery or fovea to isolate visual field effects.
• The relationship between individual differences in visual field appearance and perceptual bias was examined.

Main Results:

• Observers showed a disproportionate bias towards perceiving circularity increases, regardless of the actual change direction.
• Shapes were perceived as more circular when presented in the periphery compared to the fovea.
• A stronger perception of circularity in the periphery relative to the fovea correlated with a reduced bias for reporting circularity increases.

Conclusions:

• Visual field differences exert both direct and indirect influences on transsaccadic shape perception.
• Direct influence stems from distinct shape appearances in central vs. peripheral vision, affecting perceived change magnitude.
• Indirect influence arises from transsaccadic expectations, where deviations from learned patterns generate error signals that enhance change detection.