Effects of response task on reaction time and the detection of affordances.

Studies on affordance perception commonly report systematic errors; a finding that is at odds with the observation that everyday motor behavior is accurate. The present study investigated whether the means by which perceptual performance is measured could explain the reported errors. Perception of overhead reachability and reaction time were measured using a verbal and an actual reaching response in a standing reach, and a reach-and-jump. Results show that participants accurately perceived their action boundaries for both tasks and in both response conditions. A simple reach, however, took less time to initiate (1,094 ms) than a reach-and jump (1,214 ms). Interestingly, the verbal response took considerably more time to initiate (1,424 ms) than the actual reach (1,154 ms). These results suggest that making verbal judgments about affordances is a different task than actually acting on them. It is therefore concluded that the use of conscious judgments to measure perceptual performance should be considered with care.