negative contrast effect

negative contrast effect

A term of art used in operant conditioning referring to the decline in response rate when the size of a reinforcer (reward) is reduced to a rate below that seen in subjects who had been receiving a smaller reinforcers ab initio.
References in periodicals archive ?
Successive negative contrast effect in instrumental runway behaviour: A study with Roman high- (RHA) and Roman low- (RLA) avoidance rats.
Successive negative contrast effect in one-way avoidance learning in female roman rats.
In no case did doing so lead to a negative contrast effect in responding for 1% sucrose in the first component.
But it did not produce a systematic negative contrast effect. Positive induction (observed for 2 subjects) was still observed twice as often as negative contrast (observed for 1 subject).
In short, although it remains possible that food-pellet reinforcement may potentially produce a negative contrast effect in responding for 1% sucrose, the present study found little evidence to indicate under what conditions this outcome would be observed.
The partial reinforcement effect and the successive negative contrast effect were among these results.
The second involves paramagnetic/super paramagnetic contrast agents based on iron oxide nanoparticles that produce strong T2/T2 negative contrast effects.1112
Such decrements in responding have been termed negative contrast effects (NCE).
Although negative contrast effects in consummatory behavior are typically demonstrated using food-deprived subjects (Flaherty, 1982; Flaherty, Becker, & Checke, 1983; Flaherty & Largen, 1975.), NCE has also been obtained with nondeprived subjects (Brazier & Dachowski, 1991; Flaherty & Largen, 1975; Riley & Dunlap, 1979).
Subjects in a currently nondeprived state should respond to the hedonic value of the solutions and display enduring and recurring positive and negative contrast effects characteristic of nondeprived subjects, regardless of their initial deprivation condition.
Although the mean weight of initially deprived subjects remained significantly below that of initially nondeprived subjects throughout Phase 2, the pattern of negative contrast effects was characteristic of the current deprivation condition.
Within-subjects positive and negative contrast effects in rats.