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Cognitive control can involve proactive and reactive mechanisms. Little is known about pro-and reactive control in visual search, when observers look for pre-defined targets among distractors. Using a gaze-contingent eye-tracking paradigm, we recently provided evidence consistent with different modes of control in multiple-target search. We instructed participants to simultaneously search for two possible target objects presented among distractors, and select one of them. In one condition, only one of the two targets was available in each display, so that the choice was imposed, and a reactive control mechanism would be required. In the other condition, both targets were present in a search display, which gave observers free choice over what to search for, and allowed for proactive control. Switch costs emerged when targets were imposed, while no switch costs emerged when target selection was free. Using a …