Perception of Kinematic Characteristics in the Motion of Lifted Weight

Abstract

It has been widely shown that human observers are able to perceive lifted weight from the observation of a point-light display of the lifter's action. In the experiments reported here, the kinematic information used by observers to perceive a lifted weight was determined. In Experiment 1, observers (N = 30) were able to identify weights (5, 10, 15, 20, and 25 kg) successfully by observing only the lift phase of the action. Other procedures, such as walking while holding the weight and placing the weight on a table, did not result in significantly improved estimations. In Experiment 2, the kinematic patterns used by 4 lifters with weights varying from 5 to 25 kg were examined. Changes in weight lifted resulted in changes in lift velocity, hip angle, and dwell time. In Experiment 3, in which 15 observers participated, these 3 kinematic variables were experimentally manipulated. The results indicated that observation was most significantly influenced by variations in lift velocity. The results are discussed in relation to kinematic specification of dynamics and heuristic approaches.

Observing how others lift light or heavy objects: Which visual cues mediate the encoding of muscular force in the primary motor cortex?

“…Moreover, when transcranial magnetic stimulation (TMS) is applied during the mere observation of actions, the primary motor cortex (M1) becomes increasingly activated in a strictly time-locked and gle these distinct visual features and to characterize their relative contribution in mediating force-encoding within the observer's motor system. Overall, three types of visual features can be distinguished that may contribute to a person's ability to infer the applied force from observing the grasping and lifting of a bottle: A first important cue is the perceived kinematic pattern by which the bottle is grasped and lifted (Bingham, 1987;Grezes, Frith, & Passingham, 2004;Hamilton, Joyce, Flanagan, Frith, & Wolpert, 2007a;Shim & Carlton, 1997). For example, if the bottle is heavy, the durations of the grasp-and lift-phase will be longer, than for lifting a lighter bottle.…”

The relative influences of movement kinematics and extrinsic object characteristics on the perception of lifted weight

“…For instance, PLD research has identified that sufficient information is contained in movement kinematics for observers to discriminate the weights of objects lifted by an actor (Runeson & Frykholm, 1981), even when the actor feigns the weight of the object that is being lifting (Runeson & Frykholm, 1983). Specifically, the actor's hip angle, the period of time between the actor establishing a purchase and lifting the object, and lifting velocity contribute to the observer's ability to detect the true weight of a lifted object (Bingham, 1987;Hamilton & Grafton, 2007;Shim & Carlton, 1997). However, the extrinsic visual characteristics of a lifted object also represent sources of information that can influence the perception of the lifting movement (see R. S. Johansson & Cole, 1994, for a review).…”

Perceiving movement patterns: Implications for skill evaluation, correction and development. [Percepción de los patrones de movimiento: Implicaciones para la evaluación, corrección y el desarrollo de habilidades].

“…Specifically, the experts pick up of proximally (earlier) occurring advance information suggests their advantage lies in their ability to perceive and understand kinematic information -a contention supported through studies of "Point Light Displays" (PLDs) presenting only kinematic information (Abernethy & Zawi, 2007;Kozlowski & Cutting, 1977;Shim & Carlton, 1997). Further, to their ability to utilize advance information, it appears skilled performers adopt a more 'global' rather than 'local' strategy, relying on multiple sources of information to inform their judgments (Williams, Huys, Cañal-Bruland, & Hagemann, 2009).…”