Previous studies have shown that the level of complexity of paired-associates tasks can be measured on the basis of the quantification of programmed reinforcement probabilities in the presence of the two discriminative dimensions of these tasks. In Experiment 1 (six students) of the present paper, possible differential effects of changes in reinforcement probability for these two dimensions were investigated (to learn n responses associated to the same events versus to learn n responses each one associated to a different event). In Experiment 2 (16 students), the number of discriminative dimensions of the first member of the associated pairs varied from two (shape and position) to four (shape, position, color, and secondary shape). In general, results suggest that performance increases with increases in the level of univocal correspondence between discriminative stimuli and responses. The observed effects can be explained on the basis of changes in the programmed probabilities of reinforcement in the presence of different dimensions.
behavior analysis; precurrent behavior; task complexity; stimuli dimensions; paired-associates
