Task-relevance and change detection in action-effect binding.

Features of actions are bound to coincidentally occurring stimuli so that re-encountering a stimulus retrieves a previous action episode. One hallmark of the purported mechanism in binding/retrieval tasks is a reliable reaction time advantage for repeating a previous response if tone stimuli repeat rather than alternate across trials. Other measures than reaction times yielded surprisingly mixed results, however. This is particularly true for continuous response features like force or response duration. We therefore conducted two experiments to resolve this disconnect between different measures. Experiment 1 tested for a potentially inflated effect in reaction time data, whereas Experiment 2 took the converse approach of studying conditions that would elicit similarly strong effects on alternative measures. Our results show that confounds in terms of auditory change detection do not inflate reaction time differences, reinforcing an interpretation of these effects as reflecting binding and retrieval. Moreover, strong effects on alternative measures appeared if these features were rendered task-relevant and came with sufficient variability. These observations provide critical evidence for binding and retrieval accounts, especially by showing that these accounts extend from binary decisions to continuous features of an actual motor response.