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Andrei Gorea, Delphine Rider; Introspecting on the timing of one's actions in a visuo-motor synchronization task. Journal of Vision 2011;11(11):1215. doi: 10.1167/11.11.1215.
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It is frequently claimed that the intention to perform an action is postdictively “constructed” by its perpetrator to match the action's outcome. Accordingly, the experience of volition presumably arises at the cost of causality. We test negatively one instance of such causality violation while showing that subjects fail to discriminate between their reactive and delayed motor responses. Subjects had to (1) synchronize a key-press with the end of a synchronization interval (SI) randomly chosen to be shorter or longer than their reaction time (RT) and (2) judge thereafter whether (Q1) SI had been sufficiently long to allow synchronization (requiring introspection of their mean RT), (Q2) their motor response had been “reactive” (i.e. close to their RT) or delayed (requiring introspection on their RT and on their actual motor response time), or (Q3) whether SI was short or long (with respect to its implicit mean over trials; an “objective” judgment). SI was identified by the filling-up time (0 to 500 ms) of an annular “gauge”. Subjects' best “synchronization” motor response should be reactive for SIRT. Instead, the distributions of the motor response times were bimodal for the shortest (0 ms) and longest (500 ms) SIs and widely spread for intermediate SIs. Similarly to their responses to the “objective” question Q3, subjects' introspective responses to questions Q1,2 strongly correlated with SI itself (r = .62–.76) and barely with their actual response times (r = .03–.42). Hence subjects' introspective judgments Q1,2 were not “corrupted” by the outcome of their actions speaking against a causality violation. Subjects' reliance on the actual SI when deciding whether their action had been reactive or delayed (Q2) implies that they do not have retrospective access to (or do not remember) their motor decisions which amounts to say that they cannot decide on the intentionality of their actions.
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