Sorting test as a measurement of expansion of equivalence classes

Abstract

Previous studies have documented that sorting test can be used as an adequate measure for formation and expansion of equivalence class. Beside the inclusion of a meaningful stimulus in the set of stimuli increases the probabilities of equivalence class emergence. The present experiment intends to examine the discriminative function of meaningful stimuli in the expansion of class size and to confirm the concordance of sorting test with MTS test. Using a simultaneous protocol in a Linear Series structure (ABCDE), twelve baseline relations were trained with an MTS procedure in 20 participants. The formation of the three 5-members equivalence classes (four abstract stimuli- one meaningful) was tested by using sorting test. After the partition of the stimuli into classes, the participants conducted simple discrimination training of the C meaningful stimuli towards the novel F stimuli. Subsequently, participants were randomly assigned to two groups that differed in the F stimuli. For the first group the F stimuli were numerical digits, while for the second, the dots of a dice. A double sorting test was used for testing the expansion of the classes. Eighteen of the participants showed immediate partition of the stimuli into classes. No differences were documented between the two groups, indicating that the meaningful stimuli facilitated the expansion of the equivalence class size both for the group with the numerical digits and the group with the dice. No nodal effect in reaction time was documented for none of the groups.