Multimodal mental comparisons in those with and without aphantasia

People self-report a vast range of mental imagery experiences, from vivid and realistic to none whatsoever (i.e., aphantasia). Aphantasia aside, quantifying and measuring individual differences in mental imagery skill remains a significant challenge, with research reliant on the self-report Vividness of Visual Imagery Questionnaire (VVIQ). Currently, there are very few behavioural tasks measuring mental imagery, hence we used the mental comparisons task (MCT - Suggate, 2024) in which participants mentally compare a visual, auditory, or tactile property of stimuli in the physical absence of those objects. Using an online pre-registered study, we tested performance on the MCT for participants who have aphantasia (n = 48) versus those without (n = 95). In addition to the MCT and VVIQ, measures included the Plymouth Sensory Imagery Questionnaire, and questions on how they solved the MCT task. Consistent with other work, there appeared to be small non-significant correlations between self-report and behavioural measures. Aphantasics as a group appeared generally slower, but more accurate, on the MCT. Correcting for speed-accuracy trade-offs via balanced integration scores revealed that aphantasics had an advantage on tactile stimuli. In summary, findings support the idea that aphantasic participants have preserved performance generally, with better tactile mental processing. The extent to which the MCT measures voluntary mental imagery, or can be solved without imagery altogether, is discussed.