What is aphantasia? A conceptual articulation and empirical evaluation.

Abstract

In 2015, Adam Zeman and colleagues coined the term "aphantasia" to describe the apparent inability of some individuals to conjure mental images, leading to the virtual rediscovery of this condition and sparking renewed interest in the literature on mental imagery. Ten years later, where do we stand? This article surveys current empirical research on aphantasia, focusing on five recently published comparative neurophysiological studies and how they mesh with four hypotheses proposed to account for reports of absence of mental imagery. These hypotheses explain such reports in terms of (i) a discrepancy in the use of concepts, (ii) a failure of introspection, (iii) a deficit in access to imagistic representations, and (iv) an absence of imagistic representations. The article concludes that these studies reveal neural differences between aphantasics and other individuals that allow us to reject the first two hypotheses and to consolidate the latter two as plausible explanations of aphantasia, with the final hypothesis emerging in a comparatively stronger position to provide a general account. The nature of the neural differences between these groups and how to understand them, however, remain far from clear, and the resolution of this issue presupposes the resolution of an ongoing debate between two neural models of mental imagery.