What do we see out of the corner of our eye? The role of visual pivots and gaze anchors in sport

Research focusing on perceptual-cognitive skill in sport is abundant. However, the existing qualitative syntheses of this research lack the quantitative detail necessary to determine the magnitude of differences between groups of varying levels of skills, thereby limiting the theoretical and practical contribution of this body of literature. We present a meta-analytic review focusing on perceptual-cognitive skill in sport (N = 42 studies, 388 effect sizes) with the primary aim of quantifying expertise differences. Effects were calculated for a variety of dependent measures (i.e., response accuracy, response time, number of visual fixations, visual fixation duration, and quiet eye period) using point-biserial correlation. Results indicated that experts are better than nonexperts in picking up perceptual cues, as revealed by measures of response accuracy and response time. Systematic differences in visual search behaviors were also observed, with experts using fewer fixations of longer duration, including prolonged quiet eye periods, compared with non-experts. Several factors (e.g., sport type, research paradigm employed, and stimulus presentation modality) significantly moderated the relationship between level of expertise and perceptual-cognitive skill. Practical and theoretical implications are presented and suggestions for empirical work are provided.

Human vision is stable and continuous in spite of the incessant interruptions produced by saccadic eye movements. These rapid eye movements serve vision by directing the high resolution fovea rapidly from one part of the visual scene to another. They should detract from vision because they generate two major problems: displacement of the retinal image with each saccade and blurring of the image during the saccade. This review considers the substantial advances in understanding the neuronal mechanisms underlying this visual stability derived primarily from neuronal recording and inactivation studies in the monkey, an excellent model for systems in the human brain. For the first problem, saccadic displacement, two neuronal candidates are salient. First are the neurons in frontal and parietal cortex with shifting receptive fields that provide anticipatory activity with each saccade and are driven by a corollary discharge. These could provide the mechanism for a retinotopic hypothesis of visual stability and possibly for a transsaccadic memory hypothesis, The second neuronal mechanism is provided by neurons whose visual response is modulated by eye position (gain field neurons) or are largely independent of eye position (real position neurons), and these neurons could provide the basis for a spatiotopic hypothesis. For the second problem, saccadic suppression, visual masking and corollary discharge are well established mechanisms, and possible neuronal correlates have been identified for each.

We used a novel methodological approach to examine skill-based differences in anticipation and visual search behaviour during the penalty kick in soccer. Expert and novice goalkeepers were required to move a joystick in response to penalty kicks presented on film. The proportion of penalties saved was assessed, as well as the frequency and time of initiation of joystick corrections. Visual search behaviour was examined using an eye movement registration system. Expert goalkeepers were generally more accurate in predicting the direction of the penalty kick, waited longer before initiating a response and made fewer corrective movements with the joystick. The expert goalkeepers used a more efficient search strategy involving fewer fixations of longer duration to less disparate areas of the display. The novices spent longer fixating on the trunk, arms and hips, whereas the experts found the kicking leg, non-kicking leg and ball areas to be more informative, particularly as the moment of foot-ball contact approached. No differences in visual search behaviour were observed between successful and unsuccessful penalties. The results have implications for improving anticipation skill at penalty kicks.