Abstract
Past experiments have demonstrated two distinct modes of searching a display: singleton detection and feature search. Due to the explicit template-based attentional control subsumed within feature search mode, singleton detection mode is often assumed to be comparatively less mentally effortful. This assumption fits with the fact that attention allocation is less efficient when engaging in singleton detection mode: People take the “easy way out” of search to the detriment of performance. However, this assumption remains untested. In a series of four experiments, we used a hand dynamometer to relate physical effort to perceived mental effort across different search conditions. In Experiment 1, participants completed blocks of trials in which the target was a circle among heterogeneous shapes (feature search) or an unpredictable shape singleton (singleton detection). By squeezing the hand dynamometer, participants could reduce the number of trials in each block in proportion to the amount of physical effort exerted. Surprisingly, participants exerted more effort to avoid singleton detection trials. Experiment 2 conceptually replicated Experiment 1, except that participants could instead exert physical effort to change which type of search task they needed to perform. Again, participants were strongly inclined to work to avoid singleton detection trials. Experiment 3 was identical to Experiment 2 except that we made singleton detection optional by fixing the target shape on singleton detection trials such that it was only ever a diamond. Again, the pattern of results was fully replicated. In Experiment 4, we removed the physical effort component and simply asked participants to self-report how effortful they perceived each type of search to be. Participants robustly indicated that singleton detection trials were more effortful. In contrast to widely held assumptions, our findings suggest that engaging in feature search is in fact less mentally effortful than searching for a singleton.