The aim of this study was to describe and compare the gaze behaviour patterns of expert and near expert under 19 level rugby union players during one-on-one defensive play. Gaze characteristics such as the areas of interest visited, the number of fixations, the duration of each fixation, the starting and last fixations; and the order of fixations adopted were used to achieve the aim of the study. In addition, biographical data, including sporting and vision history, were collected. Data of the two groups were described and compared with statistically and practically significant differences been highlighted. Inferential statistics were used and the following significant levels set: p<.05 for t-tests and Chi-sq'ared - tests while Cohen's d (absolute value) ≥0.20 and Cramér‟s V ≥0.10 were used to determine the practical significance for statistically significant results, respectively. An exploratory and quasi-experimental design was used, in which 81 participants (16 – 19 years of age) were sampled for differences between experts' and near experts' visual-search strategies and gaze behaviour patterns when anticipating the direction of deceptive running skills in rugby union, however, only 68 participants had eye tracker data analyzed due to the strict calibration criteria. The expert players correctly anticipated significantly (t-stat = -3.16, p = .002, d = 0.71) more than the near expert players on average (75.76% compared to 66.46%), and therefore, were less susceptible to deceptive running skills. The near expert players were, however, more aware of their fixation location than expert players. Both expert and near expert players fixated considerably more on the knees and hips than any other area of interest, however expert players had fewer, but longer fixations than near expert players per run with 4.29 ± 1.89 fixations (χ2 = 3.90, p = .048, V = 0.24) of 0.420 ± 0.140 seconds (χ2 = 3.97, p = .046, V = 0.24) compared to 5.34 ± 2.39 fixations of 0.350 ± 0.150 seconds. Both the expert and near expert groups fixated more on the lower body than the upper body on average, however, the near expert players fixated significantly more off the body for all correct runs than the expert players (t-stat = 2.17, p = .034, d = 0.53). The expert players start fixating more on the knees at the start of each trial, whereas the near expert players start fixating more on the knees and hips, and considerably off-target. The expert players fixate significantly more on the knees (t-stat = -2.56, p = .013, d = 0.63) at the end of each trial than the near expert players on average, whereas the near expert players fixate more on the hips. The orders of fixation did not yield any discernable patterns between expert and near expert players for correctly anticipated runs. Experts exhibit superior visual-search strategies and gaze behaviour control, presumably using the top-down approach, to successfully anticipate an opponent's intended direction. This information could help coaches teach perceptual tackling skills to enhance motor learning and performance.

The aim of this study was to identify and compare the gaze behaviour of both advancement levels (Advanced and Not Advanced) and genders (female and male) during successful serve reception. A quantitative, exploratory and quasi-experimental research design was used in which 50 ToppVolley Norway student athletes aged 16 to 19 years were sampled. The gaze behaviour of junior volleyball athletes was assesed as they received two types of serves (1 float and 1 top spin jump serve) and performed a forearm and/or overhead pass to a setter’s target while wearing an ASL mobile eye tracker. Gaze characteristics such as fixation number, fixation duration and areas of interest were used to achieve the aim of the study. The study found that Advanced participants differed from the Not Advanced athletes in employing fewer (9.70 ± 1.14 versus 10.77 ± 3.63 , p<.05, d>.20 ) fixations but for longer durations per fixations (1.64 ± 0.20 versus 1.60 ± 0.34, p<.05, d>.20 ) in receiving the float serve. Contrary, for the reception of the top spin jump serve, the Advanced athletes employed more fixations (12.11 ± 2.40 versus 11.83 ± 2.17, p<.05, d>.20 ) but for shorter durations per fixations (1.57 ± 0.26 versus 1.65 ± 0.34 sec, p<.05, d>.20 ) than the Not Advanced athletes. Male athletes in this study were more experienced than their female counterparts (5.97 ± 1.62 years versus 4.75 ± 1.59 years, p<.05, d>.20 ) with males employing more fixations than the females (11.02 ± 3.63 versus 9.19 ± 1.55 and 12.26 ± 2.46 versus 11.36 ± 1.69, p<.05, d>.20 ) for the float and top spin serves respectively but for shorter durations per fixation (1.62 ± 0.27 versus 1.76 ± 0.29 sec (float) and 1.56 ± 0.32 versus 1.73 ± 0.28 sec (top spin) p<.05, d>.20 ) than the female athletes. These results and findings suggests that Advanced athletes for both serves attended to the most appropriate visual information through the top-down approach, their knowledge and past experiences. For gender differences, the results show that the female athletes employed fewer fixation points in receiving float serves, however the employment of fewer fixation points during the top spin jump serves was due to receiving serves characterised by easily identifiable trajectories and lower speeds. The contradicting finding of the Advanced athletes employing more fixation points for the top spin jump serve may be due to task complexity demands. Thirteen areas of interests were also identified. The combined results for both gender and advancement levels suggest that the athletes fixated on similar areas of interests, primarily the upper body and secondary on the ball (flight), serve reception phase, arrival at target and contact point. The aim and objectives of this study were achieved in that both absolute and relative values for number of fixations, duration of fixations and areas of interest fixated on, were established. However the outcome of comparisons made, were not all expected particularly that of the Advanced group for the top spin jump serve. Possible explanations were offered, but further research is required in this regard.

The present work is based on the Visual Routine theory of Shimon Ullman. This theory holds that efficient visual perception is managed by first applying spatially parallel methods to an initial input image in order to construct the basic representation-maps of features within the image. Then, this phase is followed by the application of serial methods - visual routines - which are applied to the most salient items in these and other subsequently created maps. Recent work in the visual routine tradition is reviewed, as well as relevant psychological work on preattentive and attentive vision. An analysis is made of the problem of devising a visual routine language for computing geometric properties and relations. The most useful basic representations to compute directly from a world of 2-D geometric shapes are determined. An argument is made for the case that an experimental program is required to establish which basic operations and which methods for controlling them will lead to the efficient computation of geometric properties and relations. A description is given of an implemented computer system which can correctly compute, in images of simple 2-D geometric shapes, the properties vertical, horizontal, closed, and convex, and the relations inside, outside, touching, centred-in, connected, parallel, and being-part-of. The visual routines which compute these, the basic operations out of which the visual routines are composed, and the important logic which controls the goal-directed application of the routines to the image are all described in detail. The entire system is embedded in a Question-and-Answer system which is capable of answering questions of an image, such as "Find all the squares inside triangles" or "Find all the vertical bars outside of closed convex shapes." By asking many such questions about various test images, the effectiveness of the visual routines and their controlling logic is demonstrated. / Science, Faculty of / Computer Science, Department of / Graduate

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A model based on the laws of classical conditioning is posed as an explanation for the McCollough Effect, an orientation-specific color aftereffect. This model stands as an alternative to the color-coded edge detector hypothesis. Background and relevant issues are presented. Two experiments were performed. The first demonstrated that an auditory stimulus causes the effect to appear stronger to some subjects, a disinhibiting effect. It was also shown that some subjects experience spontaneous recovery of the effect after it has been extinguished.

A fully counterbalanced extension of the Bauer and Efstathiou (1965) study involved exposing 11 Ss to lateral prismatic displacement for five minutes and measuring their adaptation to it. The difference between pointings at a target taken before and after prismatic exposure constitutes an adaptive shift.

Common experience suggests that most people can tell whether they are being looked at by another person who is about 8 m away. However, the results of past experiments, which used distances of no more than about 3 m, have implied that this cannot be done if the person looked at (Receiver) judges only by the iris-sclera configuration of the person looking (Sender). This is true even if eye contact is defined simply as identifying on-face gazes (FGs). It has been suggested that in everyday experience eye contact is accompanied by cues other than iris position, and that these non-iris-position (NIP) cues to Receiver account for recognition at longer distances. The hypotheses of the present experiment are that FGs can be identified at considerably more than 3 m, without NIP cues: and that this happens because as features of Sender's lower face fall within Receiver's central vision at longer distances, Receiver is able to use them for triangulating the position of Sender's irises.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Psychology, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND HUMANITIES. / Vita. / Bibliography: leaves 183-190. / by Alex Paul Pentland. / Ph.D.

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