Positive discrimination contrast with delay of reward or low drive
In the present study, six groups of 10 albino rats each were given differential conditioning training in parallel alleys differing only in brightness. The results showed a positive S+ contrast effect when 20-sec delay of reinforcement or lowered drive (12-h deprivation) were used to lower responding, but a negative S+ contrast effect when subjects received both immediate reinforcement and 23-h deprivation. No present theory can adequately explain both effects. © 1975, The Psychonomic Society, Inc.. All rights reserved.
Calef, Richard S., Ruth Ann B. Calef, Frederick R. Maxwell, and Earl R. McHewitt. "Positive discrimination contrast with delay of reward or low drive." Bulletin of the Psychonomic Society 6, no. 1 (1975): 120-122.
Bulletin of the Psychonomic Society