Schedule of Events | Symposia

Attention induces a left hemispheric lateralization for three-dimensional shape from shading: an ERP study

Poster Session A - Saturday, March 29, 2025, 3:00 – 5:00 pm EDT, Back Bay Ballroom/Republic Ballroom

Joshua Matthews¹ (jsm22cvd@bangor.ac.uk), Paloma Marí-Beffa¹, Debra Mills¹, Ayelet Sapir¹; ¹Bangor University

Despite retinal input providing only two-dimensional (2D) information, three-dimensional (3D) shape can be inferred from depth cues in the environment. For instance, the shading pattern across an object can be used to derive 3D shape in a process termed shape from shading. Early evidence suggested that shape from shading is a pre-attentive process, however recent findings imply that attention is necessary to perceive 3D shape from shading. Here, we explore this notion using event-related potentials (ERPs), specifically by examining the N2pc (posterior contralateral) component as a measure of attentional resources. We hypothesised that 3D stimuli would evoke a larger N2pc amplitude than 2D stimuli. Furthermore, in line with evidence suggesting a right hemispheric dominance in 3D perception, we predicted that this effect would be lateralized to the right hemisphere. Participants were presented with 2D and 3D stimuli in the left and right visual field. At the beginning of each experimental block, a target shape was defined, and participants were asked to indicate the location of the target stimulus. We found that N2pc amplitude was greater for 3D targets compared to 2D targets, but this effect was only significant over the left hemisphere. Thus, the current study demonstrates that increased attentional resources are necessary to identify 3D shapes defined by shading cues. Interestingly, as we also found that this effect was lateralized to the left hemisphere, it supports alternative suggestions that the ventral visual pathway in the left hemisphere is involved in processing 3D shape.

Topic Area: ATTENTION: Other