Reinforcer predictability and stimulus salience promote discriminated habit learning.

Instrumental (operant) behavior can be goal directed, but after extended practice it can become a habit triggered by environmental stimuli. There is little information, however, about the variables that encourage habit learning, or about the development of discriminated habits that are actually triggered by specific stimuli. (Most studies of habit in animal learning have used free-operant methods.) In the present experiments, rats received training in which a lever press was reinforced only in the presence of a discrete stimulus (S) and the status of the behavior as goal-directed or habitual was determined by reinforcer devaluation tests. Experiment 1 compared lever insertion and an auditory cue (tone) in their ability to support habit learning. Despite prior speculation in the literature, the "salient" lever insertion S was not better than the tone at supporting habit, although the rats learned more rapidly to respond in its presence. Experiment 2 then examined the role of reinforcer predictability with the brief (6-s) tone S. Lever pressing during the tone was reinforced on either every trial or on 50% of trials; habit was observed only with the highly predictable (100%) relationship between S and the reinforcer. Experiment 3 replicated this effect with the tone in a modified procedure and found that lever insertion contrastingly encouraged habit regardless of reinforcer predictability. The results support an interactive role for reinforcer predictability and stimulus salience in discriminated habit learning. (PsycInfo Database Record (c) 2021 APA, all rights reserved).