Equivalence class formation in a trace stimulus pairing two-response format: effects of response labels and prior programmed transitivity induction

Abstract

Three experiments identified factors that did and did not enhance the formation of two-node four-member equivalence classes when training and testing were conducted with trials presented in a trace stimulus pairing two-response (SP2R) format. All trials contained two separately presented stimuli. Half of the trials, called within-class trials, contained stimuli from the same class while the other half, called cross class trials, contained stimuli from different classes. On within class trials, making a YES response was correct and making a NO response was wrong. On cross class trials, making a NO response was correct and making a YES response was wrong. In Experiment 1, similar intermediate percentages of participants (about 50%) formed classes, regardless of whether the responses were labeled YES and NO or SAME and DIFF. Response labeling thus did not influence class formation. Regardless of response labels, failures of class formation were primarily due to failure of class-indicative responding produced by within-class transitivity probes. In Experiment 2, only 50% of participants formed classes without prior training, as in Experiment 1, but 100% of participants formed equivalence classes after the establishment of a generalized transitivity repertoire by use of a programmed transitivity induction protocol. Experiment 3 examined two components of the programmed transitivity induction protocol and found that the exclusion of AC trials had no effect on the percentage of participants who formed equivalence classes, while presenting the stimulus sets in randomized order interfered with equivalence class formation. A further analysis found that a number of stimulus control topographies differentiated between individuals who did and did not form equivalence classes. In general, then, these experiments demonstrate that equivalence classes can be formed reliably when training and testing are conducted in an SP2R format, supporting the view that equivalence class formation can account for the development of conceptual categories in natural settings.

Keywords: college students; equivalence classes; generalized transitivity repertoire; keyboarding; successive matching trial format; trace stimulus-pairing two-response trial format.

Fig 1

Number of participants in the YES/NO and SAME/DIFF groups (Conditions I and II) in Experiment 1 who began each condition (total height of each bar), who completed each condition (white portion of each bar), and who did not complete each phase of the condition (gray portion of each bar). The phases used in each condition were preliminary training (TFT), three-member class formation (3M), maintenance of three-member classes (3MIX), expansion of class size from three to four members (4MIX), and maintenance during a delayed matching-to-sample test (DMTS). When the height of a bar to the right of an adjacent bar is lower than the adjacent bar, the difference is due to subjects dropping out of the experiment between conditions.

Fig 2

Number of participants in Conditions I and II of Experiment 2 who began each condition (total height of each bar), who completed each phase (white portion of each bar), and did not complete each condition (gray portion of each bar). The phases of the experiment in each condition were preliminary training (TFT for Condition I and Programmed Transitivity Induction (PTI) for Condition II), three-member class formation (3M), maintenance of three-member classes (3MIX), expansion of class size from three to four members (4MIX), and maintenance during a delayed matching-to-sample test (DMTS). When the height of a bar to the right of an adjacent bar is lower than the adjacent bar, the difference is due to subjects dropping out of the experiment between conditions.

Fig 3

Figure 3 illustrates the number of participants who started and completed each phase of Experiment 3 in Conditions I, II, and III. The format of this figure is like that used for Figures 1 and 2.

Fig 4

Blocks to mastery in each phase of equivalence class formation for participants who did and did not form equivalence classes are shown in the left and right hand columns, respectively. The data included in a given panel were averaged for all participants included in the condition. The abscissae for all graphs indicate the phases used during equivalence class induction. AB1, AB2, AB3, and AB4 refer to training conditions in which feedback was provided for 100%, 75%, 25%, and 0% of the trials in a block, respectively, and likewise for the training of the other baseline relations. Data in each row are for different conditions in Experiments 2 and 3 and are indicated by the labels in the rightmost section of each row. The N values in each panel indicate the number of participants from whom data were included in the averages. The error bars indicate +/− 1 Standard Error (SE). The absence of an error bar means that all participants performed in the same manner during that phase. See text and tables for further information.