The behavioral performance and cortical structural properties of aphantasia

Mental imagery is an important cognitive function in human beings, but its neural mechanism remains largely unclear. Recent studies reported that some people were not able to voluntarily generate visual imagery, and this phenomenon was termed “aphantasia”. Further research on aphantasia found that, besides imagery, other cognitive functions in aphantasic individuals seemed to be similar as the normal population, such as visual working memory. The current study quantitatively measured aphantasic individuals’ abilities to imagine static and moving visual stimuli, and investigated the possible strategies to complete visual working memory tasks. Using the binocular rivalry paradigm with static stimuli, we confirmed that aphantasic individuals could not imagine static stimuli. However, after imagining dots moving in a coherent direction, a motion aftereffect was observed in aphantasic participants, which was similar to control participants with normal imagery ability. For visual working memory tests, aphantasic individuals showed similar capacities as control, and their performances were attenuated by semantic interference but not by external luminance. Control participants showed a different interference pattern, where they were impacted by concurrent luminant but not semantic disruptions. This suggested that aphantasic individuals used semantic ways to maintain visual information to compensate for the loss of visual imagery. In addition, the gray matter volumes were measured with MRI for aphantasic individuals. The results showed that compared with control (N = 18), aphantasic individuals (N = 14) had smaller anterior cingulate cortex (ACC) in the right hemisphere and medial frontal gyrus (MFG) in both hemispheres, which were related to the executive functions and attention, respectively, of the brain. The current study provided more evidence on the behavioral performances in aphantasia, and explored structural differences in the gray matters between aphantasia and control groups.