Instructions, stimulus equivalence, and stimulus sorting: Effects of sequential testing arrangements and a default option

The present study was a modified replication of a paper-and-pencil format s tudy by Eikeseth, Rosales-Ruiz, Duarte, and Baer (1997) on equivalence rela tions derived from instructionally induced conditional relations. The study consisted of three experiments, all with Dutch psychology students as subj ects. After being instructed to memorize four printed examples of arbitrary AB and B-C conditional discrimination tasks and completing A-B and B-C tri als in the presence of these examples, the subjects received a series of pr obe trials (no access to the examples): baseline and symmetric transitivity (C-A) probes (Experiment 1), or baseline, symmetry (B-A, C-B), and symmetr ic transitivity probes followed by a sorting test (Experiments 2 and 3). Wi thout the option to skip "impossible-to-solve" probe trials (Experiments 1 and 2), almost all subjects (99%) completed all training and all probe tria ls. Most subjects (87%) who responded correctly on the baseline training tr ials also responded correctly on the baseline probes. Most of these subject s responded correctly on the symmetry trials (87%), the symmetric transitiv ity probes (81%), and on the sorting test (76%). Symmetric transitivity was seen most often when tested after symmetry. The performances on the sortin g test corresponded with the numbers of derived relations (symmetry and tra nsitivity; symmetry or symmetric transitivity; no symmetry nor symmetric tr ansitivity) rather than with equivalence per se. The introduction of the de fault option (Experiment 3) resulted in most subjects skipping and respondi ng inaccurately on the symmetry and symmetric transitivity probes.