Probing the unimaginable: The impact of aphantasia on distinct domains of visual mental imagery and visual perception.
Jianghao Liu, Paolo Bartolomeo
Cortex; a journal devoted to the study of the nervous system and behavior September 1, 2023 Peer reviewed DOI: 10.1016/j.cortex.2023.06.003 via PubMed
Summary
People with aphantasia (absent or nearly absent visual imagery) can perform visual tasks as accurately as those with typical or unusually vivid imagery, but they are slower and less confident. In a study of 117 participants, 44 with aphantasia showed similar accuracy on tasks involving object shape, color, words, faces, and spatial relationships, but had slower response times in both imagery and perception tasks. Higher vividness correlated with faster response times across all domains. The findings suggest aphantasia involves slowed visual processing without loss of precision, possibly reflecting a deficit in phenomenal consciousness or use of alternative strategies.
Study at a glance
| Design | observational cohort |
|---|---|
| Sample size | 117 |
| Population | healthy adults with varying levels of visual imagery vividness |
| Key finding | Aphantasic participants showed similar accuracy to other groups on visual tasks but had slower response times and lower confidence in perceptual tasks. |
Abstract
Different individuals experience varying degrees of vividness in their visual mental images. The distribution of these variations across different imagery domains, such as object shape, color, written words, faces, and spatial relationships, remains unknown. To address this issue, we conducted a study with 117 healthy participants who reported different levels of imagery vividness. Of these participants, 44 reported experiencing absent or nearly absent visual imagery, a condition known as "aphantasia". These individuals were compared to those with typical (N = 42) or unusually vivid (N = 31) imagery ability. We used an online version of the French-language Battérie Imagination-Perception (eBIP), which consists of tasks tapping each of the above-mentioned domains, both in visual imagery and in visual perception. We recorded the accuracy and response times (RTs) of participants' responses. Aphantasic participants reached similar levels of accuracy on all tasks compared to the other groups (Bayesian repeated measures ANOVA, BF = .02). However, their RTs were slower in both imagery and perceptual tasks (BF = 266), and they had lower confidence in their responses on perceptual tasks (BF = 7.78e5). A Bayesian regression analysis revealed that there was an inverse correlation between subjective vividness and RTs for the entire participant group: higher levels of vividness were associated with faster RTs. The pattern was similar in all the explored domains. The findings suggest that individuals with congenital aphantasia experience a slowing in processing visual information in both imagery and perception, but the precision of their processing remains unaffected. The observed performance pattern lends support to the hypotheses that congenital aphantasia is primarily a deficit of phenomenal consciousness, or that it employs alternative strategies other than visualization to access preserved visual information.