The informational properties of the throwing arm for anticipation of goal-directed action

We examined the informational value of biological motion from the arm in predicting the location of a thrown ball. In three experiments, participants were classified as being skilled and less skilled based on their actual performance on the task (i.e., using a within-task criterion). We then presented participants with a range of stick figure representations and required them to predict throw direction. In Experiment 1, we presented stick figure movies of a full body throwing action, right throwing arm plus left shoulder and throwing arm only. Participants were able to anticipate throw direction above chance under all conditions irrespective of perceptual skill level, with the perceptually skilled participants excelling under full body conditions. In Experiment 2, we neutralized dynamical differences in motion to opposing throw directions from the shoulder, elbow and wrist of the throwing arm. Neutralizing the wrist location negatively affected anticipation performance in all participants reducing accuracy to below chance. In Experiment 3, we presented movies of the motion wrist location alone and the upper section of the throwing arm (shoulder-elbow). Participants were able to successfully anticipate above chance in these latter two conditions. Our findings suggest that motion of the throwing arm contains multiple sources of information that can help facilitate the anticipation of goal-directed action. Perceptually skilled participants were superior in extracting informational value from motion at both the local and global levels when compared to less skilled counterparts.