Spontaneous adaptation explains why people act faster when being imitated

Abstract

The human ability to perform joint actions is often attributed to high-level cognitive processes. For example, the finding that action leaders act faster when imitated by their partners has been interpreted as evidence for anticipation of the other’s actions (Pfister, Dignath, Hommel, & Kunde, 2013). In two experiments, we showed that a low-level mechanism can account for this finding. Action leaders were faster when imitated than when counterimitated, but only if they could observe their partner’s actions (Exp. 1). Crucially, when due to our manipulation the partner’s imitative actions became slower than the counterimitative actions, leaders also became slower when they were imitated, and faster when counterimitated (Exp. 2). Our results suggest that spontaneous temporal adaptation is a key mechanism in joint action tasks. We argue for a reconsideration of other phenomena that have traditionally been attributed solely to high-level processes.Electronic supplementary materialThe online version of this article (doi:10.3758/s13423-016-1141-3) contains supplementary material, which is available to authorized users.

Drawn together: When motor representations ground joint actions

“…It has recently been suggested that coordination effects which were held to be a consequence of how actions are represented motorically are in fact due merely to temporal adaptation (e.g. Lelonkiewicz & Gambi, 2016). Could our findings similarly be explained merely by temporal adaptation and so not support the hypothesis that collective goals can be represented motorically?…”

What or when? The impact of anticipated social action effects is driven by action-effect compatibility, not delay

“…In all cases, compatible action-effect relations help the agent to retrieve the intended motor patterns, whereas incompatible actioneffect relations counteract efficient retrieval. The present findings therefore suggest that A-E compatibility affects action planning in social settings even when controlling for confounding influences of A-E delay (Lelonkiewicz & Gambi, 2016). Experiment 2 went one step further and p i t t e d b o t h , A -E c o m p a t i b i l i t y ( i m i t a t i o n v s .…”

“…This possibility remains to be addressed by further empirical work. Alternatively, however, this observation may also be taken to suggest a negligible role of A-E contiguity for the representation of other agents' behavior as long as the delay does not exceed a certain threshold (Lelonkiewicz & Gambi, 2016) and/or the task does not require precise temporal coordination between agents (e.g., Kourtis, Sebanz, & Knoblich, 2010). This speculation receives support from the relatively low accuracies of the detection task in Experiment 2 (pending around 72% on average) and appears to have high face validity because certain delays are a necessary feature of social interaction (because other agents will always require some time to process our actions and respond correspondingly).…”

“…suggested a sample size of 12 participants for a power of 1 -β = .80 (data taken from . We still chose to test additional participants because controlling for delays might decrease the effect size to an unknown extent (Lelonkiewicz & Gambi, 2016). All participants gave informed consent and received either course credit or monetary compensation for participation.…”

“…3) because the participant's actions also differed with regard to temporal features (short vs. long), possibly drawing attention also to other temporal features of the task. 3 Note that the results ofLelonkiewicz and Gambi (2016) do not necessarily indicate temporal adaptation but might equally be driven by anticipations of the to-be-expected A-E delay. Both explanations, however, can be taken to suggest that A-E compatibility effects in social settings are at least confounded with the effects of A-E delay, or might indeed be explained entirely by one or both alternative explanations.…”