Can only what we attend to be subliminally processed? 

Grega Repovs
Department of Psychology, Washington University in Saint Louis, Saint Louis, MO

Previous research has shown (e.g. Draine and Greenwald, 1998) that subliminal presented stimuli can influence the processing of subsequent stimuli, a phenomenon known as subliminal priming. Later studies have shown that subliminal priming occurs only when attention is directed towards the subliminal stimuli at the time of their presentation (Naccache, Blandin and Dehaene, 2002). The question arises, whether attention needs to be directed towards the relevant task and stimuli features as well, for the stimuli to be successfully subliminally processed. Asked differently, do only the features that one attends to get to be subliminally processed? To study that, a subliminal semantic priming study was set up. The participants were requested to make speeded judgments about either animacy or gender of the presented words. The task was carried out in three conditions. The information about the required judgment was provided either at the beginning of the block, as a cue two seconds before the presentation of the target, or simultaneously with the target word. In all cases subliminal primes - either congruent or incongruent in relation to the requested judgment - were presented before the target word. At the time the subliminal stimuli were presented, the subject paid preparatory attention, selective attention or no attention to the relevant aspect of the stimulus. The results showed that the priming effect was present only in the cases when the cue preceded the presentation of the subliminal stimulus. Based on these results it seems that attention to the task and the specific feature of the stimuli is needed for that feature of the subliminal stimulus to be processed. Subliminal perception seems to be as much guided by attention as conscious perception is, the only difference being in the extent of its influence and the ability to consciously report the stimulus. The task, however, required the participants to map the responses to both possible judgments to the same two keys, creating a response conflict between the two stimulus features. It could be, that both features of the stimuli are subliminally processed, but the attention is needed for the conflict between them to be resolved and the processing to be observed as priming effect. To test that possibility, a set of experiments is being carried out in which every response can be made independently of another, eliminating a possibility of conflict. The results of the study will be presented and the role of attention in subliminal perception will be discussed.