Mental imagery, reasoning, and blindness
Quarterly Journal of Experimental Psychology
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. One of the most fundamental and frequently asked questions within cognitive psychology is: "What type of mental representation is used when people think, solve problems, or make decisions?" If you ask people with no education in psychology how they reason, many of them say that they rely on visual mental images. For instance, with a problem such as: Adam is taller than Brenda. Brenda is taller than Cathy.