We report three experiments on visual mental imagery in de-ductive reasoning. Reasoning performance of sighted partici-pants was impeded if the materials were easy to envisage as visual mental images. Congenitally totally blind participants did not show this visual-impedance effect. Blindfolded par-ticipants with normal vision showed the same pattern of per-formance as the sighted. We conclude that irrelevant visual detail can be a nuisance in reasoning and impedes the process
