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The behavioral performance and cortical structural properties of aphantasia

DOI: 10.1167/jov.23.9.5985
Chang, S., Wang, J., & Meng, M. (2023). The behavioral performance and cortical structural properties of aphantasia. Journal of Vision, 23(9), 5985. doi:10.1167/jov.23.9.5985

Abstract

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.

Authors

  • Shuai Chang4
  • Jinhui Wang1
  • Ming Meng4

Understanding Aphantasia: Insights into Visual Imagery and Brain Structure

Overview/Introduction

Aphantasia is a unique condition where individuals are unable to voluntarily create mental images. While most people can visualize images in their mind, those with aphantasia experience a blank mental canvas. This study delves into how aphantasia affects the ability to imagine visual stimuli and explores the brain's structural differences in individuals with this condition.

Methodology

The researchers employed a variety of tests to assess the mental imagery and visual working memory of individuals with aphantasia:
  • Participants: The study involved 14 individuals with aphantasia and 18 control participants with normal imagery abilities.
  • Binocular Rivalry Paradigm: This method was used to evaluate the ability to imagine static and moving visual stimuli.
  • Visual Working Memory Tests: These tests measured how well participants could retain visual information amidst different types of interference.
  • MRI Scans: Brain scans were conducted to examine structural differences in gray matter between the two groups.

Key Findings

  • Imagery Abilities: Aphantasic individuals struggled to imagine static images but could perceive motion aftereffects similarly to those with normal imagery abilities.
  • Visual Working Memory: Both groups showed similar capacities, but their performance was affected differently:
  • Aphantasic individuals were more impacted by semantic interference (e.g., language-based distractions).
  • Control participants were more affected by changes in external luminance (e.g., light intensity).
  • Brain Structure Differences: MRI scans revealed that individuals with aphantasia had smaller gray matter volumes in specific brain regions:
  • Anterior Cingulate Cortex (ACC): Linked to executive functions.
  • Medial Frontal Gyrus (MFG): Associated with attention.

Implications

These findings suggest that aphantasia does not significantly impair cognitive functions like visual working memory. Instead, individuals with aphantasia may rely more on semantic strategies to process visual information. Understanding these differences can help tailor cognitive and educational strategies for those with aphantasia, enhancing their learning and memory retention.

Limitations

While the study provides valuable insights, it is limited by a small sample size, which may affect the generalizability of the findings. Further research with larger groups is needed to confirm these results and explore additional cognitive aspects of aphantasia.
In summary, this study sheds light on the intriguing condition of aphantasia, revealing how it affects mental imagery and brain structure, and offering a foundation for future research and practical applications.