![]() ![]() ![]() Although the resulting displays consist only of a set of moving dots, they nonetheless convey a compelling impression of a person moving and contain enough information to perform very complex perceptual judgments (for reviews see 24, 25). Notably, RM has been also reported when human movements were presented by means of impoverished point-light stimuli (PLS), which are stimuli that consist of dots moving with the main joints of an actor performing different actions 23. This effect is robust to changes of the actor in the priming movies and the test images 21 and does not occur for biomechanically impossible movements 22. Furthermore, recognition performances of briefly presented images of actions are higher when the images are in temporal continuity with previously presented priming movies of those actions 20. An early study by Thornton and Hayes reported RM when observing stimuli of crowds moving in different contexts 7. In agreement with that, several studies have consistently found RM also for stimuli displaying human actions and movements. As is the case with objects and events in our environment, also interacting with other people and objects relies on simulating how their and our own movements respectively will unfold in time. At the same time, we also act upon and interact with objects in our environment. We are a social species and thus, we constantly engage in social interactions with our conspecifics. Finally, for an elliptical motion, it was reported that the displacement of the target reported along the tangential and inward directions were consistent with centripetal forces ( 18, but see 19).Īn important class of dynamic stimuli that we encounter in our everyday life is other People’s and our own movements. Furthermore, RM was shown to depend on the degree of perceived “friction” and “gravitational force” experienced by the moving stimulus 15, 16, 17. For example, it was shown that the degree of forward mislocalization of a moving target depends on both its velocity 11, 12, 13, 14 and acceleration 14. It was shown to be modulated by several characteristics of the stimulus. Representational momentum has been reported for a wide variety of experimental conditions and perceptual domains (see reviews in 8, 9, 10). A remarkable example of that is representational momentum (RM 6), which is “the tendency for observers to misremember the stopping point of an event as being further forward in the direction of movement or change” 7. ![]() In the specific case of visual perception, its predictive nature was acknowledged very early, already in von Helmholtz’s classic work 1 and later confirmed and corroborated by several experimental findings 2, 3, 4, 5. These predictions are indeed necessary to compensate for the intrinsic delays that our sensory and motor systems have in processing the incoming information and in generating appropriate behavioral responses respectively. We live in a continuously changing environment and the ability to predict its future states has high behavioral relevance. This simulation process seems to be independent from the point of view under which the actions are observed. We interpret these findings as evidence that full-body stimuli elicit a simulation process that is closer to the instantaneous veridical configuration of the observed movements while impoverished displays (both point-light and single-dot) elicit a prediction that is further forward in time. It was also smaller when first-person full body stimuli were compared with a stimulus consisting of a solid shape moving with the same physical motion. This misrepresentation was however significantly smaller for full-body stimuli compared to point-light and single dot displays and it was not modulated by the point of view. In all conditions, subjects tended to misremember the last configuration of the observed stimulus as being further forward than the veridical last showed position. In a representational momentum paradigm, we then asked subjects to report the perceived last position of an observed movement at the moment in which the stimulus was randomly stopped. Crucially, the underlying physical characteristics of the movement were the same in all conditions. ![]() To this end, we motion captured the elliptical arm movement of a human actor and used these trajectories to animate a photorealistic avatar, a point-light stimulus or a single dot rendered either from an egocentric or an allocentric point of view. Here, we investigated whether the instantaneous internal representation of an observed action is modulated by the point of view under which an action is observed and the stimulus type. Observing the actions of others triggers, in our brain, an internal and automatic simulation of its unfolding in time. ![]()
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