Some properties of the visual imagery system investigated through backward spelling

Kosslyn (1973) and Kosslyn, Ball and Reiser (in press) have claimed that a quasi perceptual “scanning” process operates on visual images. Lea (1975) has suggested that this process should be redescribed in terms of iteration through an underlying list structure. It is known that images are subject to capacity limitations. This restriction of processing capacity suggests a model of imagery in which only information displayed in the image may be scanned, while iteration operates between such successive information displays. Three experiments on backward spelling from images support this view. Words of greater length involve more iteration problems. In Experiment I, backward spelling took longer than forward spelling for 8-letter but not for 4-letter words. Experiment II provides evidence for a directional scanning process, using a Brooksian interference technique. Experiment III demonstrates that the structure of the internal representation affects the manner in which it is iterated and that subjects can modify their iteration strategies.