An investigation of perception without awareness

Abstract

Following the work of Dixon (1971) some experiments were performed to investigate two aspects of perception without awareness, the handling of emotional stimuli and the relation between subliminal perception and selective attention.

Apparatus was designed which utilized the phenomenon of binocular rivalry, so that an image (above identification level when presented alone) could be masked by a brighter image to the other eye and thus perceived without awareness. An experiment of Smith et al. (1959) was replicated with improved controls. It was shown that responses to words presented outside of awareness tended to be meaning-related, the same words yielding structure-related responses when presented supraliminally.

Spence (1967) proposed an explanation of perceptual defence in terms of the interaction of arousal and memory. Some experimental support for this idea was obtained. Further experiments on the handling of emotive stimuli led to the conclusion that individual differences in perception are an important factor to be controlled. Similarly, further to Brown (1965,1971) it was concluded that the stimulus characteristics of emotive words used as experimental stimuli need to be better controlled. An explanation of word association phenomena in terms of the interaction of arousal and attention was discussed and the perceptual defence and WAT situations contrasted.

Finally, two brief experiments illustrated aspects of the selective attention paradigm relevant to perception without awareness: pre-attentive processes (Neisser, 1967) and incidental stimulation (Eagle et al, 1966). Following a review of selective attention experiments, including evidence of unattended channel processing, some tentative proposals were made which might encompass the material presented. Utilizing a model suggested by MacKay (1972) it was proposed that the phenomena of perception without awareness represent the functioning of an early stage in the normal perceptual process essential both to the handling of emotive stimuli and the selection of inputs to awareness.