Visual Search and Biological Motion Perception in Tennis. (Research Note)

Article excerpt

Key words: anticipation, minimal essential information, relative motion, skill

The interpretation of relative motion is a fundamental process in perception. For instance, the need to accurately identify changes in an opponent's body movements prior to shot execution illustrates the importance of motion perception in tennis. In fast ball sports, a performer is presented with a diversity of information within a constantly changing perceptual array. To deal with this complexity, the visuoperceptual system appears to use a Gestalt-like perceptual grouping process to organize the display into its simplest terms. The visual system can perceive patterns of motion using this minimum principle (Cutting & Proffit, 1982). Scully and Newell (1985) claimed that the key to discriminating one action from another is in the simplistic perception of movement invariance. The suggestion is that performers are able to pick up salient information from the relative motions of the body and use this information in determining a response.

Biological motion displays provide an example of such minimal information, isolating kinematic information from "pictorial" cues via the presentation of human motion in point-light form (e.g., see Johansson, 1973, 1976). Several authors have noted the ability of naive observers to differentiate human movement patterns presented using point-light displays (e.g., see Bertenthal, Proffitt, Spetner, & Thomas, 1985; Cutting, Proffitt, & Kozlowski, 1978; Runeson & Frykholm, 1981, 1983). It has been suggested that experience affects the pickup of biological motion information and is one of the most significant factors in interpreting its meaningfulness (Proffitt & Gilden, 1989; Runeson, 1984; Scully, 1986). Expert-novice differences in information pickup, and subsequent interpretation, have been demonstrated extensively in previous research (for an up-to-date review, see Williams, Davids, & Williams, 1999). These differences are thought to reflect greater attunement to the relative motions and kinematic properties o f an opponent's action. Preliminary research suggests that expert-novice differences in anticipatory performance are due to the ability to pick up minimal information from joint kinematics, as presented in point-light form. Abernethy and Parker (1989) noted that although expert and novice participants demonstrated an "inevitable" reduction in performance when viewing point-light compared with film displays, participants were able to use information presented in point-light form to determine the direction and force of a squash stroke. In both point-light and normal conditions, experts outperformed novice participants to a similar extent. In contrast, Shim and Carlton (1999) observed a progressive deterioration in expert performance across, "live," film, and point-light conditions, whereas novices did not significantly differ across viewing conditions. Experts demonstrated superior performance throughout and were differentiated from novices by their greater ability to use kinematic information in the point-ligh t condition. In the film and live conditions, the addition of structural and contextual information added to the expertise effect. However, some of the findings may have been confounded by differences in the model's movement characteristics between the live and filmed conditions and in subsequent comparisons across these conditions. In light of this potential limitation and the contradictory findings reported, further research is required to clarify the issue.

Previous anticipation research has investigated whether experts and novices can be differentiated on the basis of their visual search strategies in time-constrained contexts (e.g., Singer, Cauraugh, Chen, Steinberg, & Frehlich; 1996; Williams & Davids, 1998). This research has attempted to locate the temporal and spatial characteristics of salient cues during an anticipatory response. During a tennis ground stroke, experts have been shown to fixate around central body areas, particularly the waist-hip region, as well as racket and racket-ball contact areas of the display. …