Does Perceiving Throwabiliy Require a Task Specific Device?

Abstract Throwing performance, throwability perception and subjectively felt heaviness all depend on object size and weight. Here we investigate how size and weight must be detected to perceive throwability. In previous studies, the size-weight relation was detected by hefting an object in the hand and looking at it. Thus, it could be that detecting the size-weight relation and perceiving throwability entail a visual-kinesthetic multisensory process. On the other hand, it may be that a task-specific, action-relevant perceptual organization is required, meaning that we must perform a hand-arm action that is analogous to throwing to detect the perceptual information for throwability. In this case, haptic detection of size and weight via hefting would be sufficient. We tested these alternative hypotheses by manipulating the hefting method and found that when participants visually detected size and kinesthetically detected weight, they perceived throwability less accurately and less precisely than when detecting size and weight just haptically. Only in the latter case was felt heaviness consistent with perceived throwability. Hefting with eyes open or closed led to equivalent affordance perception and thus, perceiving throwability did not require multisensory processing. These results supported the task-specific device theory.