Eye Movements During Conditional Discrimination Training

Abstract

We examined eye movements in younger and older adults during conditional discrimination training and testing for responding in accordance with stimulus equivalence. During training, we measured fixation duration and fixation rate for both the sample and comparison stimuli. During testing, we measured fixation duration and fixation rate for the comparison stimuli only. In addition, we measured the establishment of conditional discriminations and likelihood of responding in accordance with stimulus equivalence. The results showed that the effect of the differential reinforcement procedure occurred more slowly in the older participants. Fixation rate and fixation duration toward the sample stimulus was similar for both groups, whereas fixation rate and fixation duration toward the comparison stimuli were generally higher for the older adults, particularly for those who failed to respond in accordance with stimulus equivalence. Fixation rate and fixation duration generally decreased across training, with a stepwise increase in both behaviors during testing of the baseline conditional discriminations, symmetry, and equivalence relations. The same pattern recurred in the last part of testing, although generally with shorter fixation durations and lower fixation rates relative to the beginning of testing.