The impact of mental images on reasoning: A study on aphantasia

There is a long-standing debate about the role of visual mental images in reasoning. Knauff and Johnson-Laird's (2002) Visual Imagery Impedance Effect (VIIE) suggests visual imagery can hinder abstract reasoning, as evidenced by slower responses to visual compared to spatial and control problems. Aphantasia, reduced or absent visual imagery, offers a unique opportunity to test this hypothesis. In an online version of the reasoning paradigm used in VIIE studies, aphantasics and typical imagers completed three problem types (visual, spatial, control), while reaction times and accuracy scores were measured. In addition, a second classification, based on the Object-Spatial Imagery and Verbal Questionnaire (OSIVQ), was employed to differentiate participants according to their cognitive style and explore possible performance differences between the visualiser, spatialiser and verbaliser clusters. While our study replicated the VIIE in typical imagers, demonstrating robust evidence of a slowdown for visual problems in comparison to spatial and control ones, the effect was inconclusive for aphantasics. Although inconclusive, our results suggest that the VIIE may be smaller in participants with aphantasia than in those without. Furthermore, when complete aphantasics are distinguished from hypophantasics, we observed that the former may have a smaller VIIE than the latter. Finally, our OSIVQ classification-based analyses revealed a meaningful slowdown in reasoning for the visualiser cluster, pointing to a possible influence of cognitive style on performance. Overall, our results demonstrated the importance of considering the influence of mental images and cognitive styles in theories of reasoning.