Signaling as a context-dependent strategy in action control.

In sequential two-choice tasks, performance is typically improved when both the stimulus features and the response are repeated but worsens when only one of them repeats and the other changes (partial repetition costs). The signaling account assumes a bias of response selection towards a repetition or change by applying a heuristic that uses the relation between previous and current stimulus features as a response signal. We investigated whether the signaling heuristic is modulated by contextual information, specifically the comparability of different display set sizes that signal a response with either few or many stimuli. Participants worked through a sequential task while display set sizes were varied within (Exp. 1, N = 45; enabling comparison between displays), or between participants (Exp. 2; N = 130, enabling no comparison between displays). Contrary to findings in typical two-choice tasks, partial repetition costs were not observed with small set sizes and only emerged at larger set sizes in Experiment 1 but were similar in Experiment 2. These results suggest that signaling incorporates context information to adapt the usage of stimulus information for response strategies in accordance with the environment.