Effects of Limited Hold on Equivalence Class Formation

In an attempt to limit the opportunity to engage in mediating behavior, two groups of adult participants received preliminary training in identity matching with limited hold levels (LH) for responding of 0.7 s for the sample and 1.2 s for the comparisons. The two groups were subsequently trained to form three 5-member classes, using the same LH levels, where the A, B, D, and E stimuli were abstract stimuli, and the C stimuli were meaningful pictures. In two tests for emergent relations, the LH for Group Short was unchanged, whereas 5 s were added to the LH for the comparisons for Group Long. None of the participants in Group Short responded in accordance with stimulus equivalence in either of the two tests. In Group Long, one participant responded in accordance with stimulus equivalence in the first test, and an additional eight participants formed equivalence classes in the second test.

Steady State Generalization following Testing with Different Inter-Probe-Test Intervals

Rats received discrimination training, wherein the S+ was a light-on (100 ft-c) and the S— was a light-off (0 ft-c). The schedules of reinforcement during S+ were a fixed-interval 30-sec. schedule with a limited hold of 5-sec. for two rats and a variable interval 30-sec. schedule for 3 Ss. After discrimination performance had stabilized, a probe-testing technique was used to test for generalization to three logarithmically arranged test stimuli (1, 25, and 50 ft-c). Tests were conducted with 5- and 2-day intertest intervals. The results indicated no difference in gradient shape after testing with 5- or 2-day intertest intervals. It was concluded that repeated probe testing for generalization virtually eliminates cumulative extinction effects that may distort gradient shapes.