The effect of stimulus duration on over-selectivity: evidence for the role of within-compound associations

The phenomenon whereby behaviour becomes controlled by one aspect of the environment at the expense of other aspects of the environment (stimulus over-selectivity) is widespread across many intellectual and developmental disabilities. However, the theoretical mechanisms underpinnings over-selectivity are not understood. Given similarities between over-selectivity and overshadowing, exploring over-selectivity using associative learning paradigms might allow better theoretical understanding of the phenomenon. Three experiments explored over-selectivity using a simultaneous discrimination task with typically developing participants undergoing a cognitively demanding task. Experiment 1 investigated whether stimulus duration effects found within the overshadowing literature also occurred in an over-selectivity paradigm, and demonstrated that greater over-selectivity was observed when stimuli were presented for short durations (2s and 5s) compared to longer durations (10s). Experiment 2 demonstrated that a post-training revaluation procedure resulted in retrospective revaluation for stimuli presented at shorter durations (2s) and mediated extinction for stimuli presented at longer durations (10s). Such results replicate findings from the overshadowing literature that have been interpreted in terms of within-compound associations while also supporting assumptions made by an extended comparator hypothesis. Experiment 3 uses an additional control condition to further demonstrate that the retrospective revaluation is a genuine revaluation effect. Additionally, the experiment provides further evidence for the within-compound association explanation of the results through manipulating the consistency with which elements of a compound were paired during training. Taken together, the findings highlight the necessity to consider the role of within-compound associations in over-selectivity, allowing for a better understanding of over-selectivity effects