The contribution of stereo vision to one-handed catching

Abstract

Participants with normal (StereoN) and weak (StereoW) stereopsis caught tennis balls under monocular and binocular viewing at three different speed conditions. Monocular or binocular viewing did not affect catching performance in catchers with weak stereopsis, while the StereoN group caught more balls under binocular vision as compared with the monocular condition. These effects were more pronounced with increasing ball speed. Kinematic analysis of the catch partially corroborated these findings. These results indicate that StereoW catchers have not developed a compensatory strategy for information pick-up, and that negative effects of a lack of stereopsis grow larger as temporal constraints become more severe. These findings also support the notion that several monocular and/or binocular information sources can be used in the control of interceptive action.

Stereo vision enhances the learning of a catching skill

“…Alternative depth cues might prove useful in situations where temporal constraints are not too severe, like in braking and parking a car in the conditions described in the study by Bauer et al (2000). Our results show that such compensations may not be suYcient to successfully deal with interceptive tasks under high temporal constraints (Lenoir et al 1999;Mazyn et al 2004). Even more importantly, a lack of stereopsis cannot easily be compensated for by task-speciWc and extensive training either.…”

“…Since stereo vision might contribute to the perception of depth in this task, it could provide the catcher with temporal as well as spatial information. In the Mazyn et al (2004) study, participants with good stereopsis had higher success rates as compared to the participants with a signiWcant lack of stereo vision (92 versus 75% successful catches). More speciWcally, the advantage of having good stereopsis increased with increasing velocity of the ball: at a ball speed of 14.6 m/s, participants with good stereopsis scored 83%, while catchers with low stereopsis hardly caught one ball out of two (54%).…”

“…In addition, most of these studies use healthy participants for whom a particular visual condition is a new and unusual situation, which makes comparison with the behaviour of people with an early onset lack of stereopsis problematic. For an elaboration of these arguments, see Lenoir et al (1999) and Mazyn et al (2004).…”

“…However, monocular conditions are not tantamount to a non-stereopsis condition, which necessitates a cautious interpretation of these results. 1 In addition, Lenoir et al (1999) and Mazyn et al (2004) did not Wnd evidence for successful compensatory strategies in catchers with a congenital or early onset lack of stereopsis. They showed that a lack of stereo vision is associated with a decrease in unimanual catching performance.…”

“…In this study, we focus on onehanded ball catching, a task that is featured by high temporal constraints and a reliance on-amongst others-stereo vision (Mazyn et al 2004). If stereopsis entails essential information for accurate catching performance that cannot be substituted by other informational cues, it is expected that catchers with low stereo vision will only make a limited, if any, progress during the learning period.…”