OpenUCT :: Browsing by Author "Du Preez, Peter"

Browsing by Author "Du Preez, Peter"

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Open Access
A cross-linguistic study of certain temporal features of speech in stuttering and nonstuttering children
(1986) Oosthuizen, Carol Louise; Du Preez, Peter
Four experiments were performed to measure temporal coarticulatory speech features in the perceptually fluent speech of 120 South African children. The aim was to test, in a limited way, the postulate that stuttering may be essentially a disorder of speech timing. Comparisons were made between English- and Afrikaans-speakers, between younger (mean age 4.1 years) and older (mean age 6. 7 years) children, and between stutterers and nonstop utterers. Experiment one investigated voice onset time (VOT) of word-initial voiced and voiceless bilabial and apical stop plosives in isolated eve nonsense syllables. The VOTs were measured from oscilloscopic displays. Nonparametric statistical treatment identified certain trends in the data. English-speakers used short- and long-lag categories to express voiced and voiceless initial stops respectively. They showed a developmental trend in the direction of lengthening of VOT for voiceless stops. Afrikaans-speakers used two sets of short-lag VOT without aspiration to produce voiced and voiceless stops. Voicing lead occurred randomly as a stylistic variant. The stuttering children demonstrated longer VOTs than did nonstutterers. In addition, English-speaking stutterers failed to lengthen VOT for voiceless stops in the normal manner. This was attributed to difficulty with the physiological demands of long-lag VOT. Afrikaans speakers, who did not have to contend with the long-lag category, clearly distinguished between voiced and voiceless stops by means of VOT. Experiment two dealt with the categorical labelling of nonsense syllables employing the voicing contrast. In younger nonstuttering subjects, English-speakers performed better than did Afrikaans-speakers, owing to the greater number of perceptual cues available to them. All younger subjects needed a lot of training in order to label correctly, whereas older subjects needed little training. English stutterers performed slightly poorer than did nonstutterers, while even older Afrikaans stutterers performed very poorly. It was postulated that stutterers might be dependent on perceptual cues which become redundant for nonstuttering listeners. Afrikaans stutterers were additionally handicapped by the paucity of perceptual cues in their language. In experiments three and four, medial stop closure duration in vev nonsense syllables and medial vowel durations in eve nonsense syllables were measured. English and Afrikaans nonstutterers had longer stop closure durations on voiceless-than stops and in high vowel compared with low vowel environments. A devel6p:nental trend was identified in the direction of differential stop closure lengthening. Medial vowel durations were also lengthened in voiced and voiced sibilant consonant environments. Subjects showed increasing vowel differential durations with age. Stutterers showed the normal trends towards differential medial stop closure and vowel durations but appeared to have a developmental lag in this respect relative to nonstutterers. Since stutterers did not differ from nonstutterers on measures of whole syllable duration or medial VOT it did not appear as if they were simply moving their articulators slowly. Experiments three and four probably tapped neutrally programmed coarticulatory effects, whereas the VOT measure might reflect a lower aerodynamic-neuromuscular level of speech functioning, the voicing feature being primarily involved at both levels. The possibility exists and is strengthened by the results of the categorical labelling task, that a central timing disorder, manifest as a developmental lag, may have been operating in the stuttering subjects.
Open Access
A comparative analysis of outcome with various psychotherapeutic methods
(1977) Shamley, Dorothy Antoinette Frances; Saayman, Graham; Du Preez, Peter
The University of Cape Town Child Guidance Clinic had never evaluated its efficacy as a community service nor its efficacy as a training ground for trainee clinical psychologists. Furthermore, client satisfaction with services offered had not been assessed. Hence this study was undertaken. The unique features of this study are: two types of control groups are used, a non-referred, untreated group of children and a referred untreated group of children and not the problematic defectors extensively used. Inexperienced clinical psychology trainees and experienced registered clinical psychologists conducted therapy for the two experimental groups. A survey of the literature shows that when institutions survey their efficacy the majority of studies are ex post facto. Moreover, when child guidance clinics undertake either ex post facto or prospective investigations, professionals from varying disciplines and training backgrounds are included in the survey thereby confusing the controversial issue of efficacy even further. Therefore, it was thought only to assess the efficacy of psychologists. Finally, the study gives a clear detailed description of the pitfalls of prospective research in a child guidance setting. Details are given of how research strategies had to be altered to take into account the various resistances and difficulties encountered.
Open Access
Cultural construction of psychiatric illness : a case of amafufunyane
(1990) Mdleleni, Thembeka N; Du Preez, Peter
The purpose of this study was to explore definitions of an illness condition amafunyane and the subsequent help-seeking behaviour amongst Black Psychiatric patients who were attending a psychiatric community clinic in Guguletu, a residential area for Blacks in Cape Town). Psychiatrists have always been faced with the problem of having to deal with patients who present with this condition. The concern was to do an exploratory research in this area using the Explanatory Model framework as a method of enquiry in studying the condition of amafunyane. Within the parameters of this model, Black psychiatric patients presenting at the psychiatric clinic, were studied in order to explore the context of illness definitions regarding the condition of amafunyane. Of importance also was to explore the patterns of help-seeking behaviour employed by these patients, and the effect that the psychiatric orientation adopted at the clinic had on such patterns.
Open Access
Decision-making in task-oriented and interaction-oriented groups
(1974) Schach, Liane; Boshoff, A B; Du Preez, Peter
Within an organisation, leadership involves accomplishing goals by working with and through people. This comprises the concepts of concern for the task and concern for relationships, and leadership research has been concerned with predicting the way in which these concepts interact, whether they are independent dimensions or not and how a balance may be achieved between the two. The present research follows directly on from the Ohio State Leadership studies (Fleishman and Peters, 1962) which viewed the concepts of task-orientation (Initiating Structure) and relationship-orientation (Consideration) as two separate dimensions and not as situated along a single continuum. Research following on from this (e.g. Blake and Mouton, 1964; and Hersey and Blanchard, 1969) all take this concept of these two dimensions as their starting point.
Open Access
The effect of age at which enrichment is commenced on the test performance of the white rat
(1977) Pace, Anthony Michael; Du Preez, Peter
Clarke (1968) hypothesised that the duration of the effect of early experience on behaviour would depend partly upon the potency and length of the experience and partly on age at application of this experience, but particularly on the amount and duration of subsequent reinforcement of the experience. He argued that later enrichment could reduce the effects of early sensory deprivation on the behaviour of the animal. This thesis investigates whether animals show equal effects of enrichment after longer periods of deprivation. or whether the effects of deprivation are irreversible. The thesis also investigates whether a critical period for enrichment is in operation in the juvenile phase of a rat's life. Results indicate that no critical period is in operation, and that animals show equal effects-of enrichment irrespective of the age at which they are enriched and irrespective of longer periods of deprivation.
Open Access
The effects of piracetam on psychometric performance in chronic alcoholics
(1984) Price, Anthony Edward; Du Preez, Peter
A randomised, placebo-controlled double-blind crossover design was employed in assessing the effects of piracetam treatment on the functional capacities of abstinent chronic alcoholics. A sample of 63 subjects, selected for reliability (to counteract an anticipated high drop-out rate) and for a minimum period of abstinence from problem drinking of three months was drawn from the William Slater Hospital, Rondebosch and commenced the trial. The trial consisted of two 8-week periods, with daily dosages of 4,8gm of piracetam or placebo. Subjects were assessed on a psychometric battery yielding a total of 31 scores at baseline, crossover (8 weeks) and trial termination (16 weeks). The final sample size was 48 after drop-outs and noncompliance had been taken into account. Scoring of test data for these subjects was completed before breaking protocols. Results were analysed by means, of two way analysis of variance with repeated measures on the trials variable. Only two of the 31 analyses yielded significant differences between piracetam and the placebo. These yielded opposed results, and as this number of significant results could be expected due to chance alone, it was concluded that they were probably chance results and that no differences existed between the effects of piracetam and placebo on the functional capacities of chronic alcoholics.
Open Access
Exercise dependence and its relation to eating attitudes and behaviours in male and female gym members : a quantitative and qualitative analysis
(1996) Herzsprung, Nataly Tanja; Du Preez, Peter
Generally, exercise is an adaptive behaviour that serves to enhance physical and psychological well-being. However, recently the potential abuses of engaging in excessive exercise have received much attention. Some individuals may become so caught up in their exercise routine that they may be quite unwilling or unable to stop exercising, even when it is medically or socially contraindicated. An increasing number of physically active individuals seem to be vulnerable to the 'exercise dependence' syndrome. To examine the link between exercise dependence and eating pathology, 57women and 32 men were recruited at three Health and Racquet Clubs in the Cape Town area. They varied in the type and amount of exercise involved in and expressed different degrees of the pressure to be fit versus the pressure to be thin.
Open Access
Exertion therapy for the mentally subnormal child.
(1981) Schomer, Helgo; Du Preez, Peter
The use of physical exercise as a therapeutic technique was explored with special reference to the mentally subnormal child. Advances in intellectual capability and social maturity were discussed in direct relation to .progress in motor skill and physical fitness. The prerequisites for a successful physical exercise programme for increasing intellectual and social functioning were outlined. An investigation was carried out to examine the effects of dynamic physical exertion therapy on the intellectual and social functioning of mentally subnormal children. A static physical exertion therapy condition served as control intervention. Thirty two institutionalised children matched on age, sex and diagnostic classification, participated in the 30-week programme. Heart rate at rest, heart rate at sub minimal workload and maximal oxygen consumption rate estimates served as measures of physical fitness. Changes in intellectual and social functioning were assessed by means of the Vineland Social Maturity Scale, Old South African Individual Scale, and Goodenough Draw-A-Man. Test. Highly significant improvements were recorded for the dynamic physical exertion therapy condition. Changes due to the static physical exertion therapy were less significant. The results supported the hypotheses that intensive, regular cardiovascular endurance exercises bring about marked increases in physical fitness associated with increases in intellectual and social functioning. Implications of the present study were examined and future research needs put forward.
Open Access
Experimental transformation of the perception of colour
(1972) Abramovitz, Arnold; Du Preez, Peter
This thesis presents an argument about the basis of our experience of colour. The argument is conducted by means of an interplay between a set of axioms, deductions from a particular theory (including "thought experiments" which explore the logic of those deductions), and concrete empirical evidence. The axioms and the theory are those of James G. Taylor. The title of the thesis refers to the general methodology adopted. The term "experimental transformation" carries specific connotations; and the notions from which it is derived, and to which it gives rise, have to be understood in the context of the total argument. If the argument presented is sound, then certain implications follow which, it is claimed, force us to reconsider many current assumptions about the nature of "colour sensation" and indeed about the very meaning to be ascribed to the term colour. This in turn would have significance for colour science, psychology and epistemology in general.
Open Access
Exploring the psychological effects and emotional reactions of mothers to their children's burn injury : aiming at proposed future therapeutic intervention
(1998) Bloomberg, Charissa; Du Preez, Peter
Burn injuries are traumatic, destructive and painful, they usually involve long-term medical and psychological consequences. Burns, no matter how small, always leave a certain degree of scarring. When the facial area is involved, it leaves children feeling branded for life with painful psychological effects. When the 'survivor' of the burn injury is a child, the impact of these consequences are even more severe and long term. When a child is burned, the whole family is affected. Most parents suffer the same process of guilt, anxiety and anger, whether the burn is large or small and irrespective of how the burn was caused . The trauma of the accident, the pain and fear of watching a child suffer and the difficulties of long term recovery and reintegrating the child back into the community, induces stress in most families. There has however been little description or measurement of the psychological effects on mothers in the acute post-injury stage. Unfortunately there have only been a few reported psychological interventions to assist mothers in helping them emotionally to support their injured child and family, as well as to assist them over the traumatic period. This study aims at investigating these issues and at initiating proposed future therapeutic interventions.
Open Access
The hippocampus and its electrographic activity
(1983) Hirschman, Glynne Hilton; Du Preez, Peter
The thesis is divided into two parts. The first part presents a theoretical investigation of the functions of the hippocampus. Three theories are critically examined : (i) the Douglas ( 196 71 1972) and Kimble (1968) proposal that the hippocampus forms the neural substrate of Pavlovian internal inhibition (hereafter referred to as the inhibitory theory); (ii) the Olton, Becker & Handelmann (1979) suggestion that the hippocampus serves as a "working memory" register; and (iii) the O'Keefe & Nadel (1978) hypothesis that the hippocampus functions as a cognitive map. The adequacy of the three theories is tested against anatomical, physiological and behavioural evidence, and it is concluded that only the inhibitory theory is both internally consistent and able to accommodate the data. Furthermore, a detailed evaluation of criticisms of the theory (as presented primarily by Nadel, O'Keefe and Black 1975) reveals that many of the apparent anomalies in. the literature are, in fact, consistent with the theory, while others are based on unsound data. ,Further consideration of the anatomical and behavioural evidence suggests that the hippocampus gives rise to two separate circuits: a dorsal circuit, subserving the functions of internal inhibition, and a ventral circuit, mediating external inhibition. It is posited that the latter circuit produces its disinhibitory effect via the mammillothalamic tract.
Open Access
Impulse control, substance abuse and clinical factors in habitual criminal violence : a neuropsychological approach
(1994) Van der Westhuysen, Martine J. C; Du Preez, Peter
Past research is reviewed in relation to criminal violence, psychopathy disordered impulse control and neuropsychological findings in these areas. Drawing upon publications from fields such as neurology, psychiatry and biochemistry, a theoretical foundation for a link between a functional disorder of impulse control and habitual impulsive violence is presented. Research on pharmacological treatment of violence is reviev.1ed as a possible alternative method to assist the violent offender to inhibit violent impulses. In order to assess whether functional impairment of impulse control may be a factor which contributes to the high local rate of habitual criminal violence on an interpersonal level, 50 violent and 50 nonviolent prisoners from Pollsmoor and Brandvlei Prisons in the Western Cape were compared on a self-report dyscontrol scale, neuropsychological measures of impulse control, incidence of substance abuse, prior head injury, and certain clinical and demographical variables. The violent group was selected on the basis of serving a current sentence for violent crime, plus a history of habitual interpersonal violence of a non-political nature from their criminal records in the prison files. The crime category of robbery was excluded from both subject groups, as it was considered to be a planned crime with an economic motive rather than an impulsive act of violence. The nonviolent sample was required to have no violent convictions of any nature, but the number of previous offences had to be comparable to those of the violent group. The total number of convictions per person ranged from 2 to 25 (mean 9.6).
Open Access
Ingroup bias : the effect of status, legitimacy and cooperation on intergroup relations
(1981) Finchilescu, Gillian; Du Preez, Peter
Research on the effect of intergroup cooperation on intergroup relations has produced contradictory results. The functionalist proposition that cooperation leads to the reduction of intergroup discrimination has not been widely supported by empirical evidence. An emerging trend indicates that cooperation reduces bias only in circumstances where the distinction between ingroup and outgroup can be rendered less salient. The cognitive-motivational theory of intergroup relations (Tajfel and Turner, 1979) provides a framework through which intergroup bias and the salience of group distinctiveness may be understood as a function of the group's position on a status hierarchy and the perceived legitimacy of that status order. This study considered the effect of intergroup cooperation, compared with no cooperation and with intragroup cooperation, within this framework.
Open Access
Lifestyle and mood factors in sport performance
(1995) Vergunst, Richard; Schomer, Helgo; Du Preez, Peter
Elite (n=37), sub-elite (n=37) or non-elite (n=24) sport persons participating in any one of eight individual Olympic recognized sports (archery, fencing, gymnastics, ice skating, swimming, track and field, weightlifting and wrestling) took part in the study. Age and sex of subjects were not controlled. Subjects were given the 'How Healthy a Life do you Lead?', the 'Profile of Mood States' and a general questionnaire to complete. Descriptive analysis portrayed similar lifestyle and mood profiles across the three levels of sport performance while discriminant analysis revealed that lifestyle as well as mood variables could not predict level of sport performance (p < 0.05). The research hypotheses that healthier lifestyle and mood profiles are related to better sport performance were therefore not supported. Other results however revealed that the structure of the lifestyles was related to level of sport performance. Considerations for future research in this area are discussed.
Open Access
Occupational stress : type A behaviour as a moderator of the relationships between role demands and psychological and behavioural strain
(1985) Forshaw, Brendan Mark; Du Preez, Peter
To study Type A behaviour as a moderator of relationships between role demands and psychological and behavioural strain, 234 volunteer subjects from a medium-sized life insurance society completed three questionnaires under standardized testing conditions, tapping Type A behaviour (Session 1) and various role dimensions (Session 2) and indices of strain (Session 3). Absenteeism data were taken from employee record cards, as were data for some demographic and organizational variables (race and sex), while others, (company tenure, age and organizational level) were explored in the questionnaires. Assessment sessions were staggered, with one-month intervals between each, to reduce the effects of response sets. Factor analysis of responses to the role dimensions questionnaire confirmed the hypothesized factor structure and led to the development of scales for role conflict, ambiguity, overload and qualitative underload. The reliability and validity of these scales are discussed. Partial correlations (with the linear effects of the demographic and organizational variables removed) and multiple linear regressions indicate that role conflict, ambiguity, overload and underload may be described as social-psychological stressors, in terms of psychological strain, while only underload is weakly related to absenteeism. Type A behaviour is not found to moderate relationships between stressors and strain, with the exception of an effect for underload which may be accounted for in statistical, rather than psychological, terms. Results are interpreted as evidence of the need for improved work design and redesign, particularly in South African organizations. Implications of findings with respect to sequential models of strain, as well as the nature of the relationship between Type A behaviour and CHD, are discussed.
Open Access
The operational definition of managerial roles
(1978) Harrison, Athol Mayo; Du Preez, Peter
This study aims for the first time to operationalise managerial behaviour and to produce a set of empirically-based statements of the differences in behaviour which determine managerial effectiveness or failure.
Open Access
Postevent information and the impairment of eyewitness memory : a methodological examination
(1989) Tredoux, Colin; Du Preez, Peter
Recent work in the cognitive psychology of memory suggests that misleading information may permanently alter memory for an event. This work, which takes much of its impetus from the prospect of applying itself to the legal question of eyewitness evidence, has recently come under severe criticism. McCloskey & Zaragoza (1985a, 1985b) provide evidence to suggest that the experimental design used by almost all relevant studies is seriously flawed, and that results which appear to indicate the deleterious effect of misinformation on memory are artefactual. An analysis of the misinformation paradigm is presented here, with particular attention being paid to the claim of artifactuality. Two lines of approach are adopted in the analysis. In the first, the misinformation paradigm is assessed for its theoretical basis. The notion of 'application' that informs the paradigm is subjected to conceptual scrutiny, and the body of research that constitutes the paradigm is reviewed in terms of its applied orientation. In the second line of approach, the claim of artifactuality is investigated directly. Three methods are devised to test the claim of artifactuality. In two of these, post-hoc analyses are performed, one of which suggests that the claim of artifactuality is incorrect in at least some respects. The third method is constituted by an experiment which submits the claim of artifactuality to exhaustive empirical test. The results of the experiment support the claim that findings of memorial alteration are artefactual. The two lines of approach are united by showing how the experimental work developed out of the applied basis of the paradigm.· It is argued that the inadequacies in the experimental design reflect the impoverished theoretical basis of the research. It is further argued that the question regarding the effect that false information has on memory for an event is one that is still. eminently worth pursuing. A few preliminary remarks are made regarding applied considerations relevant to this pursuit.
Open Access
Reaction time measures of perceptual and linguistic factors in a phoneme monitoring task
(1982) Bokhorst, Frank Dirk; Du Preez, Peter
Open Access
Relationship between methods of training and levels of intelligence
(1988) Mtoba, Wilhelmina Nyameka; Du Preez, Peter
The purpose of the study was to explore the feasibility of training conservation skills to a group of Black 7 - 8 year old children enrolled in a primary school in the Gugulethu township, a Black residential area in the Cape. From a group of 100 children, 60 subjects were selected on the basis of failure to conserve as measured by Piagetian conservation tasks. One of the conservation tasks was employed for training the subject to be able to conserve. A pre-test/post-test experimental design was used in a six phase experiment; assessment of possession of conservation concepts through the aid of Piagetian tasks of conservation of substance, weight, number and length; assessment of intelligence with the aid of the New South African Individual Scale; assessment of mental ability using the Draw-a-person test; group training with different methods of teaching on length conservation; immediate post test to determine effectiveness of training and transfer to other tasks and a delayed post-test to four weeks after training to assess retention of training effects.
Open Access
Relationship between prosocial moral reasoning, prosocial behavior, family functioning and social maturity in pre-primary school children
(1985) Whiting, Gillian Mary; Du Preez, Peter
The purpose of this correlation study was to attempt to account for differences in pre-schoolers moral reasoning about altruistic conflicts on the basis of healthier types of family functioning and greater degrees of· social maturity: to show whether these differences are reflected in an increase in prosocial behavior. Thirty-eight pre-school boys and girls responded to four simple moral stories about helping and sharing. (Moral R.). All responses of the children were coded by the researcher and an independent coder. Assessment of the extent of the children's own naturally occurring prosocial behavior was by the completion of a Likert-type rating scale (Pros. B.R.) by the teachers of the school. It was hypothesized that the use of more mature levels of moral reasoning would account for more prosocial behavior. Results confirmed the hypothesis. Family functioning was measured by the Family Assessment Device questionnaire (F.A.D.) and individually completed by all the mothers and fathers. The hypothesis that healthier family functioning patterns would reflect use of higher levels of moral reasoning was partially supported. The measurement of the extent of social maturity of each child was by means of a semi-structured interview with the mothers and utilizing the Vineland Social Maturity Scale (V.S.M.). It was hypothesized that healthier patterns of family functioning would foster greater social maturity. Results obtained did not support this hypothesis. Other hypotheses were; (a) that greater social maturity would account for the use of more mature levels of moral reasoning: this hypothesis was confirmed, (b) that greater social maturity would be related to increased prosocial behavior: results confirmed this hypothesis, (c) that increased prosocial behavior would be reflected by healthier patterns of family functioning: results did not support this hypothesis. As measurement was of an ordinal nature Spearman's non-parametric rank correlation was utilized. A subsidiary study was conducted in which the children's moral reasoning was examined by way of their dominant modal response. None of the pre-schoolers used the Kohlberg stage 1 authority and punishment as their modal response. Much hedonistic and needs-oriented reasoning was used. Spearman's rank correlation was used to examine relationships between the categories of moral reasoning. The use of hedonistic reasoning was negatively related to both needs orientation and stereotypic reasoning. Other relationships did not reach statistical significance.