Subliminal Perception, Neuropsychology, and the I-Function

Unconscious Processing: Subliminal Perception, Neuropsychology, and the I-Function

In his 1957 book The Hidden Persuaders, Vance Packard warned the American public that "Large-scale efforts are being made, often with impressive success, to channel our unthinking habits, our purchasing decisions, and our thought processes... Typically these efforts take place beneath our level of awareness; so that the appeals which move us are often, in a sense, hidden" (1). Packard was convinced - perhaps rightly so - that advertisers were "professional persuaders" whose marketing techniques were deceptive and overly manipulative. Not only were advertisers becomingly increasingly adept at developing campaigns, pitches, and slogans to send specific messages to targeted consumer populations, but some had gone so far as to suggest that such messages could be effective even if they were presented below the level of conscious awareness. James Vicary, one of the market researchers and entrepreneurs profiled in Packard's book, claimed to have developed a machine capable of flashing such unnoticeable, "subliminal messages" within big screen movies. Vicary had allegedly tested his technique by altering movies so that messages urging viewers to "Eat Popcorn" and to "Drink Coke" were displayed at regular intervals throughout the film for such brief durations that they could not be consciously perceived. Vicary claimed that his subliminal messages resulted in a significant increase in sales of popcorn and coke (1). Although no experiment involving subliminal messages has ever replicated the success which Vicary claimed to have achieved and, in fact, Vicary later admitted that it had been no more than a marketing gimmick, the possibility of subliminal or unconscious perception has not been dismissed. In fact, although the use of subliminal messages is generally considered a foolish and invalid practice, the more general phenomenon of subliminal/unconscious perception deserves to be reevaluated in light of current debates surrounding the nature of consciousness.

Subliminal or unconscious perception refers to the idea that stimuli presented below the threshold for conscious awareness can influence an individual's thoughts, feelings, or actions (2). The possibility that an individual can acquire and act on input without being aware of doing so has implications for the study of consciousness and the larger set of processes which characterize the I-function. It is generally assumed that that conscious perception of a stimulus is necessary in order to act on that stimulus, and this conscious decision to act is one of several processes which characterize the I-function.