According to behavioristic theories, stimuli generate
sensations, which are stored in memory. Correlations between stimuli (classical conditioning) or stimuli and behavioral responses (operant conditioning) cause these sensations to be
associated with each other to generate complex representations. However, many predictions of this approach failed when subjects responded in disagreement with the “association strengths” of stimuli. Several theoreticians then resorted to the concept of
attention as pointed out by Koffka (
1922, p. 535):
“wherever there is an effect that cannot be explained by sensation or association, there attention appears upon the stage.” A key shortcoming of behavioristic theories is their inability to define the stimulus independent of the observer, a problem known as the “stimulus definition” problem. To deal with this problem, Tolman introduced “intervening variables” to account for how internal states of the observer can modify the stimulus (Tolman,
1938). In contrast to behaviorists, Gestalt psychologists proposed that organized structures, i.e., Gestalts, form the fundamental units of visual processing (Wagemans,
2015). Hence, to define a stimulus, one needs to refer to the internal cognitive structures of the subject. Gestaltists proposed that grouping operations can generate a variety of possible groups, starting from simple ones and proceeding toward more complex ones, until the structure meets the goals of the observer. They introduced the concept of
attitude to express this active role of internal structures in giving a directness to perception, such as the expectation of a particular organization or outcome. Attention, in turn, was defined as a special case of attitude, which is
unspecific toward a particular organization or outcome. These ideas found support in experiments that employed decoy tasks to minimize the involvement of attention (Krechevsky,
1938; Köhler & Adams,
1958).