Effects of lateral reversal on recognition memory for photographs of faces.

Recognition memory for photographs of faces, which were initially shown in the normal orientation, then tested either normally (unchanged) or laterally reversed (changed), was examined in four experiments involving different experimental designs (between and within group) and different methods of testing (yes-no and forced-choice). Although the overall effect of the transformation was not as powerful as others (e.g. hair style change) which have been applied to faces, and even failed to attain statistical significance in a fifth experiment in which all the photographs were initially reversed at presentation then tested unchanged or changed back to their normal orientation, the main findings were as follows: (a) subjects recognized fewer reversed (changed) than normal (unchanged) photographs whether or not they were informed of the transformation; (b) the adverse effect of reversal occurred on faces looking straight ahead (full-faces) and, to a slightly lesser extent, on those looking to the left of the observer (left-lookers); (c) left-lookers and right-lookers (the left-lookers initially reversed in Expt 5) were less well recognized than full-faces; and (d) subjects had difficulty identifying orientation, where accuracy fell almost to chance level. These results are taken as support for a feature (rather than Gestalt) model of facial recognition in which the two sides of the face are differentiated in its memory representation.