The thesis is an account of an investigative study into the nature of perceptual-motor abilities. Part one considers Witkin's construct of cognitive style, using it to predict the relationships between three tests of perceptual functioning from widely varying areas of psychology and sports science. To some extent the results were as predicted; that is, those people demonstrating high levels of perceptual acuity on one test also showed similar acuity on one or more of the other perceptual tests. These results, however, only applied to the male subjects and then only when the opposite poles of one test-dimension were partitioned out and compared. The female subjects demonstrated no significant relationships between the three tests. As a result, it was proposed that the tests were indeed linked but by an array of underlying perceptual abilities rather than by a single, overlying cognitive or perceptual style. In the ensuing search for these abilities, 76 measures of perceptual and perceptual-motor skills were factor analysed to reveal 8 oblique perceptual-motor factors of which one was interpreted as being perceptual style. The nature of perceptual-motor abilities is discussed both in relation to clumsiness and to sports training with the emphasis being on whether such abilities are amenable to alteration. The thesis puts forward the proposal that an upper limit to each ability is fixed for each individual in early childhood but that this potential may be maximised through relevant training. The Perceptual-Motor Ability Profile was devised as a tool with which to indicate the aptitude a person evidenced for a particular sport or physical activity and was used in demonstration to describe the group abilities of four dancers with respect to the requirements of their chosen activity. Finally, a model of perceptual-motor functioning, relating the eight factors extracted, is suggested.

M.Phil. (Optometry) / In football, vision is one of the key performance indicators and ingredients of success (Buys, 2002) and it is not uncommon to find a player underperforming in the field of play due to poor vision. Football is the world’s most popular sport, with the Football World Cup finals attracting record estimations of world-wide television audiences in the billions (Clark, 2007). In this sport, players must perform motor skills and control their posture during their game, while using visual information to collaborate with other team members or to oppose the opponent (Paillard & Noe’, 2006). Visual attention plays an important role in football, where players must monitor the activities and positions of multiple players simultaneously (Memmert, Simons & Grimme, 2009). As pointed out by Coopoo, Moss, Fortuin, Freese and Cameron (2012), visual capabilities and skills cannot be assumed as natural attributes but must be tested and subjected to training according to need. In this study quantitative and descriptive research is conducted to assess the visual skills of football players. Inferential statistics are done on the collected data to explain the performance of the players: A battery of twelve (12) vision related procedures were performed on each of sixty three (63) football players from two academies in Gauteng Province. The procedures are divided into ‘hardware’ and ‘software’ visual skills (Ferreira, 2002). Using the existing protocols, a comparison with existing norms is made (Buys, 2002; Buys & Ferreira, 2008). In the present study a majority of the athletes performed better in the ‘hardware’ visual skills like static visual acuity, colour discrimination, stereopsis and fusion flexibility. The athletes did not fare better in other ‘hardware’ skills like contrast sensitivity and focus flexibility. Very few of the athletes were able to score ‘above average’ and better in the ‘software’ visual skills. According to Abernethy (1986), visual performance in sport is the interaction between the ‘hardware’ and ‘software’ visual systems, and it is the ‘software’ visual system that distinguishes experts from non-experts (Ferreira, 2002; Ludeke & Ferreira, 2003; Venter & Ferreira, 2004). The ‘hardware’ of the visual system can set the potential limit to visual performance 5 in sport but once deficiencies have been addressed, it is the ‘software’ skills that will separate experts from novices (Ferreira, 2003). The ability of the sport to divide families, communities and nations along support lines tells us that there is more importance attached to the game of football than we are willing to acknowledge. Attention must therefore be paid to the performance indicators (sports vision, etc.), which have on many occasions influenced the outcomes of games. The SPSS statistical package was used to test for any statistical significance in the correlations test between player age, player position on the field of play, and player years of experience against the players’ visual skills.

M.Phil. (Sport & Movement Studies) / Resistance training (RT) is an essential element of fitness for most sports. Most athletic activities involve faster and more powerful movements than those found in maximal strength exercises. Thus athletes could be exceptionally strong but lack explosive power. The aim of the study was to determine the possible effect of two different RT programmes on the sprinting performance of men aged 18–25. Body composition was assessed via anthropometrical measurements and lower extremity power was assessed via vertical jump and the Margaria Kalamen Power Test. Speed and acceleration will be assessed via a 40 meter, 60 meter, 80 meter and 100 meter sprint tests. Thirty athletes were randomly divided into three groups (two experimental groups n=10 each and a control group n=10). Two different RT programmes (“General”, G and “Specialised”, SP) were applied for eight weeks in the two experimental groups, while the control group (C) had no form of strength training. Both training programmes included two sessions per week, each lasting 60 minutes. Components that were tested included anthropometrical, body composition, lower extremity strength and 1RM measurements in regards to their 40m, 60m, 80m and 100m sprint time. Significant difference between SP, GP and C, at a P-value of 0.05, was determined by a dependant t-test. An independent t-test was used to determine significant difference between the three groups. The results showed that there was a significant improvement on body fat (BF) % in SP (-1.71 ± 0.21), GP (-0.19 ± 0.57) and muscle mass (MM) % in SP (1.88 ± 3.23). There was a significant difference in explosive power (MK) for the specialised group (p=0.013) and the 60m sprint for the specialised group (p=0.047). One repetition maximum (1RM) bench press (p=0.005 SP and GP), 1RM deadlift (p=0.005 SP), 1RM power clean (p=0.005 SP) and 1RM squat (p=0.005 GP) improved in the relevant groups as indicated. There was a significant difference between the groups completing a 60m sprint (p=0.022), 80m sprint (p=0.057), 100m sprint (p=0.025) and 1RM bench strength test (p=0.007) at post-test. Positive correlations were found between MM% on 60m (p=0.021), 80m (p=0.01) and 100m (p=0.019) sprinting times and MK and 40m (p=0.015) sprinting time.

Physical exercise is frequently prescribed by clinicians and researchers as an effective stress reduction technique. There has been some research to support this assertion, however the research has been varied in its methodological rigor. The design problems, variations in exercise programs, and the use of a wide range of psychological measures have made results difficult to interpret. Additionally, the psychological benefits and underlying change processes have not been clearly delineated. The purpose of this study was to conduct a meta-analysis of the research in this area in an attempt to answer specific questions regarding the role of exercise in stress reduction. This meta-analytic approach was chosen because it permits the quantitative integration of findings of several studies and consideration of the variables that may influence the variance in study outcomes. The effectiveness of exercise as a treatment for stress, the type of exercise that was most beneficial, and the type of individual who gained the most from the exercise intervention was examined. The 61 effect sizes, which were calculated from 24 studies included in the meta-analysis, were coded along with other variables considered important. Study components such as design type, stress level, type of exercise program, program length, frequency of exercise sessions, attrition rate, psychological measure, composition of sample, gender, and study type were coded as independent variables. Effect size was the dependent variable. Analysis of variance revealed that exercise was an effective stress reducer, stressed people gained a greater stress reduction effect than minimally stressed people, and there were no differences between trait and state anxiety reduction from pre- to post-exercise program. In addition, a one-way ANOVA indicated that there was a significant difference between program lengths. Examination of the means revealed that an 8- to 12-week program was most effective in reducing stress. Although there was a greater effect size for unpublished studies than published studies, the pattern of change for each study type was similar. The significance of these results and recommendations for future studies are discussed. / Education, Faculty of / Curriculum and Pedagogy (EDCP), Department of / Graduate

Previous research has found little support for cognitive vulnerability factors in depression. I argue that this lack of support is due to the use of tasks that tap into effortful processes, as seen in previous research. I propose that support for cognitive vulnerability factors would be found by using tasks which tap into automatic processes. Depressive automatic processes were assessed by three tasks: dichotic listening, probe detection, and implicit memory tasks. For the dichotic listening task, subjects shadowed brief neutral passages while depression- and positive-content words were played in the unattended channel. Concurrently, subjects were required to detect the word "press" presented intermittently on a computer screen. Detection latencies were recorded. For the probe detection task, pairs of words were briefly presented on a computer screen, one appearing in the upper half of the screen, and one appearing in the bottom half. Three types of word pairs were used: neutral-neutral, depression-neutral, and positive-neutral. Subjects were asked to read the top word aloud. They were also required to detect the presence of a "+", which sometimes appeared in either location of the words. Detection latencies were recorded. For the implicit memory task, half of the subjects were presented with a list of words and were required to rate each word on how much they liked each word. Four types of words were used: depression-related, happiness-related, types of flowers, and types of diseases. These subjects were then asked to generate eight exemplars for each word type. The other half of the subjects were simply asked to generate eight exemplars for the word types. Depressive effortful processes were defined as self-report of cognitions. This was assessed by three self-report questionnaires: Dysfunctional Attitude Scale, Automatic Thoughts Questionnaire, and the Hopelessness Scale. Three groups of subjects were used: currently depressed patients (n=20), remitted depressed individuals (n=20), and nondepressed individuals (n=20). The currently depressed group consisted of 13 women and 7 men, the remitted depressed group consisted of 16 women and 4 men, whereas the nondepressed group consisted of 13 women and 7 men. Their ages ranged from 23 to 65 years, with an overall average of 39.9 (SD = 11.28) years. Subjects were tested individually on each of the tasks. Three months after testing, they were asked to complete the Beck Depression Inventory. Four main hypotheses were examined: (a) currently depressed individuals would show a bias for depression-related stimuli on the automatic tasks; (b) remitted depressed individuals' pattern of performance on the automatic tasks would resemble that of the currently depressed patients; (c) remitted depressed individuals' pattern of performance on the effortful tasks would resemble that of the nondepressed individuals; and (d) measures of depressive automatic processes would be predictive of follow-up depressive symptoms. Analyses of variance and regression analyses were used. The first hypothesis was not supported. The second hypothesis was only supported for the dichotic listening task. The third hypothesis was supported, whereas the fourth hypothesis was not supported. Implications of the results to schema theory, vulnerability methodology, and clinical assessment procedures were dlscussed. / Arts, Faculty of / Psychology, Department of / Graduate

The purpose of this study was to investigate work performance on a semi-defined, low calorie diet during daily periods of light and moderately heavy activity. Four male graduate students volunteered for the ten week study which was divided into five experimental periods. During Period 1 (control) the subjects received a balanced, normal diet of usual foods providing approximately 3600 calories per day and meeting the Canadian Dietary Standards for all nutrients. During this two week period, a "normal" level of activity was maintained. Period 2 consisted of ten days on a semi-defined low calorie diet with continued "normal" activity. The low calorie diet provided, approximately 1800 calories daily, plus one multiple vitamin pill. It met the Canadian Dietary Standards for all nutrients. Period 3 was a repeat of Period 1, two weeks during which the subjects received approximately 4000 calories, per day, of the control diet. Again, "normal" activity was maintained. Period 4 consisted of ten days of the same low calorie semi-defined diet as Period 2, with an additional daily energy expenditure, per subject, of approximately 500 calories. Period 5 was the same as Periods 1 and 3, two weeks of the control diet with "normal" activity. Several physiological variables were measured during the last two days of each experimental period to ascertain the effects of the treatment conditions on the cardiorespiratory and general fitness of the subjects. Strength measurements and maximal oxygen uptake determinations remained unchanged for the duration of the study, whereas, physical work capacity (PWC 170) decreased continually, beginning in the third experimental period. Total body weight decreased during Periods 2 and 4. Period 4, which involved increased physical activity caused slightly more weight loss than Period 2. Anthropometric measurements, body composition, and body density were only slightly changed, the changes paralleling the changes in body weight. Pasting blood samples were taken twice during each experimental period; midway through the period and on the last day. Twenty-four hour urine samples were also collected on the final day of each study period. Although some minor changes did occur, most biochemical parameters remained within normal limits. The blood glucose concentrations decreased during Periods 2 and 4 and plasma free fatty acid levels increased. Plasma cholesterol levels decreased during Periods 2 and 4, as did the hematocrit, hemoglobin, total serum protein, serum albumin, and blood urea nitrogen concentrations. Plasma Vitamins A and E, as well as the serum Vitamin C levels also decreased during Periods 2 and 4. Urinary thiamine excretion increased, possibly in response to the greater percentage of calories derived from endogenous fat stores Generally speaking, the low calorie diet situations were well tolerated by the subjects. Physiological measurements indicated a change only in physical work capacity, which decreased during the study. Biochemical determinations revealed definite alterations; however, most parameters remained within the normal limits. / Land and Food Systems, Faculty of / Graduate

Recent electrophysiological studies have shown that electrical brain stimulation (EBS) can produce lasting increases in synaptic efficacy, defined as the quantitative relationship between pre- and postsynaptic activity. However, the behavioural significance of this long-term potentiation (LTP) has yet to be demonstrated clearly. The principal objective of this thesis was to determine whether increased synaptic efficacy, produced by high-frequency EBS, enhances behavioural responses to a fixed amount of presynaptic activity. Following identification of EBS parameters capable of monitoring synaptic efficacy for long periods without producing LTP, a paradigm was developed in which a single-pulse of EBS in the perforant path (PP) acquired stimulus control over the temporal pattern of operant responses. In this paradigm, postsynaptic evoked potentials in the dentate gyrus (DG) produced by the PP EBS were used to monitor synaptic efficacy on every trial of conditioning and also to measure one component of the neural activity generated by the EBS stimulus controlling the operant responses. In Experiment 3, high-frequency stimulation of the PP produced- LTP at the PP-DG synaptic interface and facilitated subsequent acquisition of stimulus control by the single pulse PP EBS. This effect could not have been due to sensitization or to the stimulus properties of the high-frequency trains. The final experiment confirmed the importance of the EBS-evoked activity in the DG to the stimulus control by the PP EBS. The rate of acquisition was directly related to the magnitude of the evoked potentials and two-stage bilateral lesions of the PP in a specific sequence reduced the probability of behavioural responses to the EBS. Taken together, these results indicate that the behavioural consequence of excitatory neural activity can be enhanced by an increase in synaptic efficacy. As such, they provide considerable support for the validity of LTP as a model of neural changes subserving learning and for physiological theories of memory based on modifications in the- strength of synaptic connections. / Arts, Faculty of / Psychology, Department of / Graduate

The rhythmic organization of speech into regular intervals (i.e. isochrony), is a strong perceptual phenomenon. However, Investigators have been unable to demonstrate the existence of isochrony in production data. It is hypothesized in this study that the intended rhythm of a speaker is in fact isochronous, but that this is obscured by several distorting influences which introduce durational irregularity at the syllable level, e.g. intrinsic duration, stress, position of the syllable in a phrase and number of syllables in a phrase. It is proposed that removing the predictable durational irregularities will yield a more regular signal, reflecting the (hypothesized) Intended Isochronous rhythm of the speaker. The latter two sources of distortion introduce progressive durational irregularity or "warping" which can be readily incorporated into an automated "dewarplng" procedure. A computer program was devised to compensate, at the syllable level for these two sources of distortion. The former two sources are not amenable to such an automated procedure, and were therefore not included. The "dewarping" program was run on the speech amplitude envelopes of two speakers, one French and one English. The results indicate that, for the French speaker, dewarping does remove some of the durational Irregularity, yielding a more regular amplitude envelope. For the English speaker, no such Improvement in regularity is obtained. This indicates that the dewarping used, which presumes the syllable as "unit" of dewarping, is appropriate for syllable-timed languages such as French, but inappropriate for stress-timed languages such as English. It therefore provides some support for isochrony in French at the syllable level. Finally, the results also give support to the hypothesis that the degree of warping perceived as regular in speech perception studies corresponds to the degree of dewarping which, conversely, yields the most regular speech amplitude envelope; however, further experimentation is necessary to determine the optimum values of the parameters of the dewarping function. / Medicine, Faculty of / Audiology and Speech Sciences, School of / Graduate

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