Mediators of the effects of magnitude of reinforcement

The characteristics of mediational mechanisms based upon magnitude of reinforcement were investigated using rats. In two experiments, two-choice discriminations were trained in which selections of one lever in one external stimulus and a second lever in another external stimulus were reinforced with food. In the first experiment, it was found that the discrimination was acquired more rapidly when one choice was reinforced with a large number of food pellets and the other with a smaller number of pellets than when other configurations of reinforcement magnitude were provided. In the second experiment, reversal of a two-choice discrimination was found to be facilitated by prior exposure of the animals to the reversed relationships between the external stimuli and magnitudes of reinforcement. These results were consistent with predictions from a stimulus or associative view of anticipatory processes based upon magnitude of reinforcement.     

The effectiveness of visual and gustatory conditioned stimuli in human classical aversive conditioning with electric shock

Thirty-six undergraduate volunteers, divided into three equal groups, were given electric shock while sipping a colored, unflavored solution (Group I): a flavored, colorless solution (Group 2); or a colored, flavored solution (Group 3), in order to determine whether human Ss respond differentially to visual and gustatory cues when the UCS is aversive electric shock. Using a standard classical discrimination procedure, the CS + was blue water for Group 1, citric acid solution for Group 2, and blue citric acid solution for Group 3. For all groups the CS- was plain water, which was never paired with electric shock. The dependent variables were derived from Staats' A-R-D theory: attitudinal change (A) and a performance measure of sip-size taken during conditioning trials (D) both confirmed the hypothesis that taste can be an effective CS when the UCS is shock, in contrast to results typically obtained with rats where visual but not taste cues are effective with a shock UCS.     

A developmental and cross-cultural study of the influences of rule structure and problem composition on the learning of conceptual classifications

Five experiments were conducted permitting direct comparisons in the way Ss of different ages and cultures solved conceptual problems. One group of problems (Traditional) could be solved using a reference rule of conjunction or disjunction. Another group of problems (Intradimensional) could be solved either by one of the reference rules, or by a structurally simpler rule. Analysis of American performance confirmed that older Ss not only solved using the simpler rule more often than younger Ss, but when they did so they solved faster. For both American age groups, solution using the simpler rule led to no difference in performance between conjunctive and disjunctive Intradimensional problems. Conjunction proved easier than disjunction only for the Traditional problems. Unlike Americans, the Kpelle of Liberia did not solve using the simpler rule, and found conjunction easier than disjunction for both Traditional and Intradimensional problems. When a memory aid was provided the Kpelle showed a pattern of performance exactly like Americans.