Probability of stimulus equivalence as a function of training design

The present study investigated differential effects of training design on probability of an equivalence outcome. Forty normal adults were assigned to four different groups. Subjects in the first three groups were exposed to a C-A equivalence test directly following linear series (AB and BC), many-to-one (AB and CB), or one-to-many (BA and BC) training, respectively, while the subjects in the fourth group, following linear series training, were exposed to a symmetry test before the C-A test. Three comparison stimuli were used throughout the experiment to minimize effects of control by negative comparisons. Number of subjects showing equivalence were highest following one-to-many training and lowest following linear series training. Several previously suggested explanations of the differential effects of training design are discussed and shown to be unsatisfactory.