The effect of meaningful stimuli on eye movements in stimulus equivalence class formation

Meaningful stimuli interspersed with abstract stimuli increase the probability of establishing conditional discriminations and responding according to stimulus equivalence in a matching-to-sample procedure, compared to procedures with only abstract stimuli. Test accuracy and reaction time have been previous experiments’ primary dependent variables. However, contemporary research on stimulus equivalence has also included eye movement measures as a means of a fine-grained analysis of behavior. The present experiment investigates meaningful stimuli’s effect on eye movements. The present experiment was arranged as a group design, with 30 adult participants allocated in three groups. All learned 12 conditional discriminations in a one-to-many training structure before testing to establish three 5-member stimulus equivalence classes. One group was trained with meaningful sample stimuli, one with meaningful comparison stimuli, and one with all abstract stimuli. Results show significant differences in fixation durations and gaze transitions between the groups with meaningful stimuli and those with all abstract stimuli in the test for stimulus equivalence. Hence, measuring eye movements with eye-tracking technology can provide information about behavioral differences between conditions not obtained with accuracy scores.