Imagining Shapes Reveals Cognitive Depth

Objective measurements of visual imagery can be gauged through pupil dilation responses. When participants visualize bright or dark objects, their pupils react similarly to actual visual stimuli—contracting for bright images and dilating for dark ones. This response is consistent in individuals with normal imagery capabilities, but those with aphantasia—characterized by the inability to visualize images—do not exhibit this pupil constriction, suggesting a potential disconnect in mental imagery processing. Additionally, introducing varying quantities of triangles influences pupil dilation, indicating that cognitive effort scales with the number of objects imagined. This set size effect appears consistent across both groups, highlighting a commonality in mental effort regardless of the presence or absence of imagery.