Abstract

Mack and Rock show evidence that no consciousperception occurs without a prior attentiveact. Subjects already executing attention taskstend to neglect visible elements extraneous tothe attentional task, apparently lacking evenbetter-than-chance ``implicit perception,''except in certain cases where the unattendedstimulus is a meaningful word or has uniquepre-tuned salience similar to that ofmeaningful words. This is highly consistentwith ``enactive'' notions that consciousnessrequires selective attention via emotional subcortical and limbic motivationalactivation as it influences anterior attentionmechanisms. Occipital activation withoutconsciousness suggests that motivated search,enacted through the organism's subcorticalmotivational functions, is needed beforevisual stimulation engenders consciousness.This enactive view – that searching for,rather than receiving or processing input isthe basis of consciousness – was slow ingaining acceptance lacking empirical evidenceof this kind, combined with thestimulus-response assumption that brain eventssubserving perceptual consciousness must resultfrom transformation of perceptual input ratherthan from the organism's self-regulatedactivity as manifested through subcorticalactivity. Implicit perception occurring withword priming is ``paradoxical'' according to Mackand Rock, suggesting late selection forattention after extensive unconsciousprocessing, while most trials involvingnonverbal rather than verbal images mightsuggest earlier selection, sinceunattended objects are unseen, apparently evenimplicitly. This paper argues that anteriorand subcortical motivational mechanisms play animportant role in early selection; posteriormechanisms then unconsciously enhance signals;if data survive early gating andcorticothalamic enhancement, then still further anterior-limbic loops motivatedlyactivate ``image schemas'' resonating withposterior nonconscious processing; at thatpoint, consciousness occurs