ABSTRACT
Concurrent discriminations involve successively presenting pairs of stimuli, with one member of the pair rewarded and the other not. The procedure is directly analogous to verbal discrimination learning in human studies. The delayed matching to sample problem has features that, if incorporated into the concurrent paradigm, may solve some of the aforementioned problems. Delayed matching usually requires a choice after a time delay between two or more stimuli, one of which previously has been presented singly and rewarded. This paradigm differs only slightly from the first two trials of discrimination problems in which a single stimulus is presented on the first trial in the manner described by Harlow and Hicks 1957. Leary studies the effects of reward and nonreward over time delays in a concurrent discrimination paradigm. His earlier work had convinced him that there were temporal changes in object attractiveness as a function of the conditions of reward.
