Two techniques for investigating perception without awareness

Abstract

Most experiments on perception without awareness seek to show effects of stimulus processing even when some forced-choice discrimination concerning that stimulus is at chance. Stimulus identification and presence-absence judgment are forced-choice discriminations concerning different aspects of the stimulus, that is, different sets of alternative stimulus states. For presence-absence judgments the relevant alternatives are a blank display versus any nonblank stimulus, whereas for identification, the relevant alternatives are the different possible nonblank states. The general logic is one of dissociation. The aim is to show that forced-choice discrimination can be dissociated from other indices of stimulus processing, such as semantic priming. Since all stimuli have many attributes, it is important to ensure that the forced-choice discrimination and the other index of processing reflect processing of the same stimulus attributes, that is, that they reflect distinctions between the same sets of alternative stimulus states. Only then can one be sure that any dissociation observed reflects the difference in response measure, rather than a difference in relevant stimulus information. © 1985 Psychonomic Society, Inc.