Differences between unmixed and mixed transfer designs as a function of paradigm

Abstract

This study compares the transfer effects in paired-associate learning obtained with unmixed and mixed designs. In an unmixed design all pairs in the successive lists conform to the same paradigm; in a mixed design the paradigm varies for different subgroups of items. An earlier study by Twedt and Underwood (1959) had shown that the two designs yield equivalent results when all the conditions of transfer included in the designs are negative. The present experiment extends the comparison between the two designs to a situation in which a condition of positive transfer (A-B, A-B′) is present along with conditions of negative transfer. All Ss learned two successive lists of 12 paired adjectives. Four paradigms of transfer were used: A-B, A-C; A-B, C-B; A-B, A-B′; C-D (control). There was a separate group for each paradigm under the unmixed condition, and four groups in the mixed condition such that each subset of 3/12 items was used equally often under each paradigm. All groups learned the same second list, with the conditions of transfer manipulated by appropriate variations of the second list. The unmixed design resulted in better performance on the transfer trials for all paradigms except C-D. The differences between the two conditions of testing, while consistent, were small. The separation between the two designs appears to be due largely to interference during mixed-list learning produced by attempts to apply multiple rules differentially to different subgroups of items.