An Eye Movement Analysis of Differential Outcomes Training: The Role of Inhibition

Abstract When differential outcomes follow correct responses to each of multiple to-be-learned associations between a sample stimulus and a comparison stimulus (the differential outcomes procedure, DOP), performance is significantly better in comparison with when the associated stimuli and the outcomes are matched randomly (the non-differential outcomes procedure, NOP). In the present study we aimed to explore the effects of using the DOP versus the NOP in participants performing an eye-movement version of the matching-to-sample task. In the first phase, participants were presented with a sample stimulus followed by an associated comparison stimulus, and then a third stimulus served as the outcome that was presented according to the DOP or NOP scheme. In the second phase, after the sample stimulus, a comparison stimulus display was presented containing the associated stimulus (i.e., the relevant stimulus associated with the sample stimulus), the non-associated stimulus (i.e., the irrelevant stimulus associated with the other sample stimulus), and two distractor stimuli. Eye movements were recorded for each type of comparison stimulus. When we compared the pattern of eye movements between the DOP and NOP, we observed a tendency to produce a lower number of refixations to the associated comparison stimulus and a significant higher number of refixations to the non-associated and distractor comparison stimuli in the DOP compared to the NOP. These results suggest that in the first phase of the DOP, during each sample-comparison trial, the non-presented sample-comparison pair was inhibited, requiring more glances for identification during the second phase. Here we provide first evidence for the role of inhibitory processes in the context of the DOP.