Mental imagery, reasoning, and blindness

TLDR

Evidence linking reasoning to visual imagery is inconclusive. Three experiments compared sighted, blindfolded sighted, and congenitally blind participants on deductive inference tasks involving visuo‑spatial, visual, and control relations. Blind participants performed worse overall but were unaffected by irrelevant visual details, whereas sighted participants’ reasoning was impeded by such visual relations, showing that visual imagery can hinder inference.

Abstract

Although reasoning seems to be inextricably linked to seeing in the "mind's eye", the evidence is equivocal. In three experiments, sighted, blindfolded sighted, and congenitally totally blind persons solved deductive inferences based on three sorts of relation: (a) visuo-spatial relations that are easy to envisage either visually or spatially, (b) visual relations that are easy to envisage visually but hard to envisage spatially, and (c) control relations that are hard to envisage both visually and spatially. In absolute terms, congenitally totally blind persons performed less accurately and more slowly than the sighted on all such tasks. In relative terms, however, the visual relations in comparison with control relations impeded the reasoning of sighted and blindfolded participants, whereas congenitally totally blind participants performed the same with the different sorts of relation. We conclude that mental images containing visual details that are irrelevant to an inference can even impede the process of reasoning. Persons who are blind from birth-and who thus do not tend to construct visual mental images-are immune to this visual-impedance effect.