The ability of human observers to discriminate aural differences in the amplitude of sinusoids, narrow-band noise, and wide-band noise was measured by the rating method of detection theory. Although each sinusoid (always 1000 Hz) was presented at a fixed amplitude, its amplitude on any trial was drawn from one of two Rayleigh probability distributions that differed in mean amplitude. Similarly, the amplitudes of the narrow-band noises were distributed as the Rayleigh distribution by virtue of the reciprocal relation between their bandwidth (100 Hz centred on 1000 Hz) and duration (10 ms). The amplitudes of the wide-band noises were distributed as chi with 82 degrees of freedom. A detection-theoretic model based on chi-square density functions was fitted to the obtained receiver operating characteristics (ROCs) and psychometric functions. The best-fitting ROCs required, on the average, 4.1 degrees of freedom for the 100-ms sinusoids and 7.3 degrees of freedom for the Rayleigh noise. The best-fitting psychometric function for both the Rayleigh noise and the sinusoids required about one degree of freedom. The results obtained for these two waveforms were not significantly different. The obtained ROCs for the wide-band noise were well fitted by the chi-square model with 82 degrees of freedom and the psychometric functions with 6.1 degrees of freedom. The best-fitting parameters for the wide- and narrow-band waveforms were significantly different. Furthermore, the performance of the observers on the nmow-band waveforms was closer to that of the corresponding ideal observer than was their performance on the wide-band waveforms. For the narrow-band noise and sinusoids, the duration of the waveform affected the variability of the best-fitting degrees of freedom for the obtained ROCs. This variability was greater for waveforms of 10-ms duration (Rayleigh noise and sinusoids) than for sinusoids of 100-ms duration; this greater variability was interpreted as stemming from the difficulty of correctly windowing short-duration waveforms. Sound pressure level had no effect on the amplitude resolution of observers for four different levels of Rayleigh noise and of sinusoids. Therefore Weber's Law, and not the near miss to Weber's Law, holds for these waveforms. The chi-square detection-theoretic model provided a good fit to the data from all experiments, but not as good as predicted by statistical theory. It was concluded that the chi-square model provides a close approximation to the underlying mechanisms involved in the amplitude resolution of Gaussian noise processes.

Despite a growing appreciation in New Zealand of the harms arising from gambling, there remains a lack of knowledge and awareness of the dangers associated with participation in gambling by young people. Although international research has demonstrated that young people are a high-risk group with regard to problem gambling, research in New Zealand has only investigated the gambling behaviour of those aged 18 and over. This thesis explores a topic that has been largely neglected within New Zealand: the relevance of gambling and problem gambling for New Zealand adolescents. A questionnaire consisting of both standardised and non-standardised items, was administered to a random sample of more than 2000 secondary school students in the Upper North Island. The role of gambling in adolescent life, the prevalence of adolescent problem gambling, and associated risk factors were investigated. This research also adopted a largely unique perspective within the youth gambling field, extending investigations to include the role of protective factors, particularly social connectedness. This investigation of protective factors supports strengths-based approaches to youth behavioural issues, with the potential to aid in the prevention or minimisation of harm, as opposed to approaches that focus upon responding to problems, as is encouraged by dysfunction-based models. This research demonstrates that gambling is part of youth culture in New Zealand. It provides the first body of data detailing the practices, beliefs, and other factors associated with adolescent gambling behaviour within New Zealand. The findings indicate that choices around gambling are strongly influenced by contextual factors and that young New Zealander’s participate in a wide variety of gambling modes. While most gamble safely, approximately four percent were observed to satisfy the problem gambling criteria. Social connectedness was strongly correlated to problem gambling behaviour and the research points towards the investigation of protective factors, resiliency, and strengths-based strategies in the future. The continuing exploration of common denominators between gambling and other dangerous consumptions also offer promising avenues for future research within the gambling field. This research demonstrates that youth gambling is an issue requiring the attention of families, communities, schools, researchers, government departments, and members of the gambling industries.

A series of experiments was undertaken to explore the effect of interaural differences in the intensity of masking noise upon the detection of a signal. The signal was a 2-kHz sinusoid, and the masker was composed of either one or two 800-Hz wide bands of noise. The centre frequencies of the two bands of noise, one above and one below the signal frequency, were varied. On most occasions both noise bands were used to create a spectral notch surrounding the signal. The following factors were manipulated: (1) The width of the notch: from 0 to 1900 Hz. (2) The location of the lower and upper frequency edges of the notch relative to the signal: either equidistant from the signal, or with one edge 150 Hz nearer to the signal than the other edge. (3) The spectrum level of the noise: either 20, 35 or 50 dB SPL. (4) The degree of interaural disparity in the intensity of some components of the noise: either 0 dB, 10 dB or infinite. (5) The ear to which a particular masking noise was sent. (6) The manner in which the noise was presented: either diotically or dichotically. (7) The manner in which the signal was presented: either diotically or monotically. The results of the first two experiments were interpreted as showing that threshold signal levels in the presence of interaural differences in the intensity of masking noise depended principally on the ear in which the signal-to-masker ratio at the output of the auditory filter was larger. To test this possibility, auditory filter shapes were derived from two listeners. These were then used to predict thresholds when there were interaural differences in the spectral envelope of a masking noise. The results of a comparison between the predicted and obtained thresholds were consistent with the previous interpretation. Thus it appears that the detector following the filter can discriminate the output of the two ears and base detection on the better output. This ability may be useful in normal listening, where both wanted and extraneous sounds are subject to change from moment to moment.

Whole document restricted, see Access Instructions file below for details of how to access the print copy. / Davison and Jenkins (1985) suggested that behaviour allocation between concurrent alternatives was affected by the the degree to which animals could discriminate between the response-reinforcer contingencies associated with each of those concurrent alternatives. The present study evaluated their models for free-operant concurrent-schedules performance and discrete-trial signal-detection performance. In Experiment 1, pigeons were trained in six sets of conditions. In each set of conditions, two intensities of white light were used as the sample stimuli in a discrete-trial signaldetection procedure. The relative reinforcer frequency for correct choice responses was varied across conditions. The same two stimuli were then arranged as the discriminative stimuli in a switching-key concurrent schedule. The relative reinforcer frequency was varied across conditions. Then the intensity of one of the white lights was varied, and these procedures were repeated for the next set of conditions. Analysis of the data from the signal-detection procedures showed that the effect of varying relative reinforcer frequency decreased as discriminability between the stimuli increased. A new model of signal-detection performance, based on the Davison and Jenkins' (1985) model of concurrent-schedule performance, accounted for this interaction. There was ordinal relation between measures of stimulus discriminability obtained from the signal-detection procedure, and measures of the effect of varying relative reinforcer frequency obtained from the concurrent-schedule procedures.

Experimental preparations may be divided into two categories, called open and closed economies. In an open economy, the extent to which the subject is deprived of the scheduled reinforcer, most commonly food, is controlled by the experimenter. This is usually done by manipulating the amount of free food given to the subject after each experimental session. Consumption of the reinforcer is thus independent of behaviour during the session. By contrast, in a closed economy, no alternative source of the reinforcer is available outside the session. Consumption of the reinforcer is thus completely determined by the subject’s interaction with the experimental environment. This may be done by having the subject live permanently within the experiment and receive all its food as reinforcers for responding on continuously available schedules. Most research in the experimental analysis of behaviour has been carried out within open economies, but it can be argued that the natural environment, as a whole, is better represented by a closed economy. Several experimental findings obtained within open economies have been shown not to be replicable within closed economies. In the present series of experiments, three pigeons received their total daily intake of food as reinforcers for responding on continuously available multiple variable-interval schedules. The relation between the allocation of responding between components of a multiple schedule and the distribution of reinforcers can be conveniently described by the generalised matching law, which states that the ratio of component response rates is a power function of the ratio of component reinforcer rates. In an open economy, the power, called sensitivity, is typically less than 1.0. This is called undermatching. Experiment 1 of the present series found sensitivity values substantially greater than 1.0.This is called overmatching. One procedural variable known to control sensitivity in open economies is level of deprivation. Experiments 2 to 5 examined the effect of deprivation in a closed economy. In Experiments 2 and 3, increasing deprivation by means of decreasing session duration produced decreases in sensitivity. In Experiment 4, increasing deprivation by decreasing overall reinforcer rate in continuous sessions had no effect on sensitivity. In Experiment 5, deprivation was held constant by changing session duration and overall reinforcer rate in opposite directions. Sensitivity increased with increasing session duration and decreasing overall reinforcer rate. Taken together, these results suggest that multiple-schedule sensitivity increases with decreasing deprivation, with decreasing overall reinforcer rate, and as the economy for reinforcers other than those arranged by the experimenter (extraneous reinforcers) becomes more closed. A quantitative model of multiple-schedule performance, elaborated from that of McLean and White (1983), was developed to account for these effects. In this model, response allocation is governed by the concurrent choice between scheduled-and extraneous-reinforcer rates within each component. The total rate of extraneous reinforcement is affected by both deprivation and economy, and the distribution of extraneous reinforcers between components depends inversely on the distribution of scheduled reinforcers. Unlike other published models, this model predicts overmatching in the present experiments. Quantitatively, the model accounts for both the present closed-economy data and published data from open-economy multiple schedules as well as does the generalised matching law, and better than does its most influential competitor, Herrnstein’s (1970) equation. Finally, it is proposed that, while the economy for scheduled reinforcers is important to understanding total response output on multiple schedules, the economy for extraneous reinforcers has much more influence on the allocation of that responding between components.

Attachment is generally described as an enduring affectional bond of substantial intensity. Bowlby’s (1982) attachment theory implies that optimal outcomes are associated with an attachment relationship that is characterised by a confidence in the accessibility and responsiveness of the caregiver. Three studies were designed to explore changes in New Zealand adolescents’ perceptions of their attachment to mothers, fathers, and friends, and the relative impact of these relationships on three measures of self esteem. Two dimensions of the attachment relationship were assessed, the utilisation of emotional support and proximity, and the quality of affect. Study 1 (n = 180) revealed that although adolescents utilised their mothers for support and proximity more than their fathers, and perceived their mothers as more responsive than fathers, they did not differ in their quality of affect towards their parents. Friends were utilised significantly more in support seeking situations than in proximity seeking situations. Study 2 (n = 493) revealed that male and female adolescents differed in their perceptions of their attachment to mothers in late adolescence. With increasing age, females reported that they would utilise maternal support and proximity more, whereas males reported utilising their mothers less in both types of situation. However, both male and female adolescents continued to report a high quality of affect towards their mothers throughout adolescence. No differences were found in male and female adolescents' perceptions of their attachment to fathers. With increasing age, males and females utilised paternal support and proximity less, and reported a lower quality of affect towards their fathers. Adolescents continued to utilise their friends highly for support throughout adolescence, and increased their utilisation of friends for proximity as they got older. Regardless of age, females reported a higher quality of affect towards their friends than males. These findings suggested that substantial changes take place in attachment relationships from early to late adolescence, and that these changes are affected by the sex of the adolescent and the sex of the parent. Further analyses revealed that Pacific Island adolescents utilised their mothers significantly less for support than European/Pakeha adolescents. Adolescents from one-parent families utilised their fathers significantly less for support and proximity, and had a lower quality of affect towards them than adolescents from two-parent families. The utilisation of support and proximity from mothers, fathers, and friends was minimally related to overall self esteem, coping abilities and social competence. The quality of affect towards mothers and fathers was significantly related to all three measures of self esteem, whereas the quality of affect towards friends was significantly related only to social competence. Adolescent attachment to parents appears to exert a relatively stronger effect on self esteem than adolescent attachment to friends, regardless of the sex or age of the adolescent. Study 3 (n = 80) examined the main reasons for utilising parents and friends for emotional support, and for feeling close to parents and friends. Content analysis revealed that the reasons did not differ according to the age or sex of the adolescent but varied according to the attachment figure. Overall, the three studies revealed that New Zealand adolescents’ descriptions of their relationships with parents and friends differed at both the cognitive-affective and behavioural levels of attachment. The divergent patterns of support seeking and proximity seeking highlighted these differences, and clearly illustrated the need to distinguish these two aspects of the behavioural dimension of attachment in adolescence. The implications of the findings for adolescent attachment to parents and friends are considered, and future directions for research are discussed.

The components of concurrent schedules of reinforcement were separated temporally by placing interval schedules on the changeover key. Both main and changeover key performances were examined as a function of the relative reinforcement rates and of the changeover schedule duration. Main key performances changed quantitatively, but not qualitatively, as the temporal separation of components increased, with performance becoming less sensitive to relative reinforcement rates with increasing temporal separation. In general, absolute response rates were adequately predicated by the relative reinforcement rates, but in some conditions the absolute response rate was also affected by the availability of the responses. The rates of responding to change between components were controlled by the reinforcement rates in the both of the concurrent schedule components, and, in some conditions, varied independently of main key response rates. The rates of responding to alternate between components were a direct function of the reinforcement rate in the absent component, and were an inverse function of the reinforcement rate for main key responding in the same component. Animals alternated between the concurrent schedule components even when alternation reduced the overall rate of obtained reinforcement.

The attentional blink (AB) refers to a decrement in detecting the occurrence of a probe item if it closely follows a previous target item in a stream of stimuli in rapid serial visual presentation (RSVP). In a series of experiments I investigated the question of hemispheric asymmetries in the AB. Experiment 1 was a simplification of the experiment by Raymond et al. (1992) to determine whether the particular stimuli and task conditions of my study would produce an AB. In Experiments 2 and 3, two RSVP streams were presented in parallel, one in each visual field. The AB occurred only when participants both identified and located the target, and not when they simply located it. When targets and probes were both presented in the right visual field (RVF), the typical AB pattern was obtained, sparing probes in the first post-target location ("lag 1 sparing"). However, the AB was greatly attenuated when both target and probe were in the left visual field (LVF). When target and probe were in different spatial locations, there was a strong decrement in detecting the probe in the first post-target position-again more marked in the RVF. Cross-stream decrements may reflect the transient effects of shifting attention, while the AB itself appeared to be largely restricted to within-stream sequences, and to processing by the left cerebral hemisphere. Experiment 4 was a further behavioural study, in which I examined differences in functional cerebral asymmetries modulated by gonadal steroid hormones during the menstrual cycle in women. Twenty-one right handed women, with regular menstrual cycle, were tested with a double RSVP task (one stream in each visual field) during the low steroid menses and the high steroid midluteal phase. An AB was obtained bilaterally in the midluteal phase, while during menses the probe detection deficit was evident only in the RVF. Low steroid levels appeared to stabilize functional cerebral asymmetries. In contrast, high levels of estradiol and progesterone in the midluteal phase appeared to reduce functional asymmetries due to a selective enhancement of the AB in the right hemisphere. In Experiment 5 and 6 I recorded event-related potentials (ERPs) to examine the temporal course of the AB. probe-related ERPs were compared between the control condition and the experimental condition when the probe was presented in the blink period (post-target position 2-4) and in the no-blink period (post-target position 6-8). In the control condition in which the subjects were told to ignore the target, there was a negative peak around 300 ms following the probe, regardless of whether the probe was presented during the blink phase or during the no-blink phase. The same peak was found for the experimental condition when the probe was presented during the no-blink phase, but was missed for probes presented during the blink phase. This finding provides strong evidence that the AB reflects an impairment in a postperceptual stage of probe processing, probably at the stage of working memory. I replicated the finding (Vogel, Luck, & Shapiro, 1998) that the AB and the P3 elicited by the target component are related. Source localisation of electrophysiological activities using low-resolution electromagnetic tomography (LORETA; Pascual-Marqui, Michel, & Lehmann, 1994) revealed reduced activation during the AB in the left cerebral hemisphere when letters were used as stimuli, whereas the right hemisphere showed reduced activation when symbols were used. / Whole document restricted, but available by request, use the feedback form to request access.

An experimental group (Group A) of 22 children around 7 years of age who had normal hearing for pure tones but who had experienced neonatal jaundice with peak bilirubin levels of at least 300 µmol/l was tested on a range of audiological tests selected to assess aspects of their central auditory processing. Children who had not been tested for bilirubin level were selected as control subjects (Group B); they were matched on the variables gender, race, gestational age, birthweight, Apgar scores and occurrence of respiratory problems. A smaller experimental group, Group C (n=7), with peak bilirubin levels between 250 and 299 µmol/l but with perinatal complications was also studied. The experimental groups had higher mean acoustic reflex thresholds and lower mean reflex amplitudes than the control group. Acoustic reflex threshold patterns of abnormality consistent with central dysfunction occurred in two children from the main experimental group and two children in the control group. None of the children from Group C showed abnormal reflex thresholds. Acoustic reflex amplitude patterns of abnormality consistent with central dysfunction were present in six children from Group A and two children from Group C, compared with three children from the control group. Masking level differences were absent in five subjects from Group A and three children from Group C, compared with three control subjects. No group differences were evident for ABR latency or amplitude measures, but poor morphology or repeatability of wave V was observed in ten subjects from Group A and three children from Group C, compared with five children from the control group. A larger number of failures within the experimental groups was found for two of the four speech tests, that is, for interrupted and filtered speech tests, but not speech in noise or competing words tests. Five children from Group A (but none from Group C) performed poorly on the interrupted speech test, compared with two from Group B. The filtered speech test was failed by six children from Group A and two children from Group C, compared with two from Group B. Parental reports of behavioural or learning disorders were distributed equally among the groups and were not associated with particular patterns of test failure. Overall, children in the experimental groups failed significantly more tests of central auditory functioning than did children in the control group (F(2,48)=5.5,p<.01). The results were interpreted as implicating jaundice in long-term central auditory processing abnormalities.

This thesis approaches the area of women's body image with the aim of expanding existing knowledge based on traditional male/female comparisons of how women respond to quantitative measures of body image. It does so by distinguishing between some different body-type groups of women. These were mostly Caucasian women aged eighteen and over who lived in the greater Auckland area. They were grouped as: normal weight (n=43); overweight (n=37); women with eating disturbances (n=27); and body builders (n=17). A pilot study involving ten normal weight women examined the face validity of several established international measures of body image as well as additional ones developed for the main study. The established questionnaires were: the Rosenberg Self Esteem Scale, the Body Esteem Scale, the Weight Locus of Control Scale, a Figure Rating Scale and a Silhouette Rating scale. The newer measures consisted of modifications made to the Figure Rating Scale and the Silhouette Rating scale. Verbal questions about teasing history were also asked, the intention being to formulate a teasing history questionnaire for the main study. These measures were found to be valid by the women. In part one of the main study quantitative comparisons between the groups revealed some differences, but also some surprising similarities. Desirable body types of normal weight and muscular physique were described positively in physical and personality terms. The undesirable body types of thin and overweight received negative descriptions irrespective of the women's own group membership. The eating disordered women scored the lowest self-esteem while the other groups did not differ. The body builders scored the highest body-esteem while the normal weight and overweight, and overweight and eating disordered groups did not differ. Correlations between self-esteem and body-esteem were significant for all groups except the body builders. The correlation was strong for the eating disordered group and moderate for the normal weight and overweight groups. In the Figure Rating Scale the body builders chose more muscular ideal figures than the other groups and for all groups the ideal and current figures were usually one figure size different. At least half the women in each group felt their body was the same size as they thought it was' Of those remaining who gave different answers to the think versus feel ratings, nearly all in the eating disordered group reported they felt bigger. In the other groups there was an even split between those who felt bigger and those who felt smaller than they thought they were. The women were most united in their selection of the figure they thought men would find most attractive. In approximately a quarter to one third of each group (excluding the body builders due to small numbers) the figure selected as attractive to men was also chosen as the self ideal. Approximately a quarter of each group [excluding body builders) selected the same self ideal and peer ideal, however a considerable percentage of women selected a larger self ideal than peer ideal. All groups reported there should not be an ideal figure at all in society. All groups tended to believe that their weight was under their own control. Most women reported having been teased about their appearance and being affected by this teasing. This was especially noticeable for the eating disordered group, a considerable percentage reporting they still felt adversely affected by it. Part two of the study introduces feminist poststructuralist theory and the Foucaultian concept of power and discourse analysis as ways to explore body image research. The body image literature introduced in part one is then revisited showing how this area of research can be harmful for women. The presentation of the interviews with 28 women follows, seven women from each body type group. A short form of discourse analysis was used for the women's responses to issues in body building, their explanations of the self-esteem, body-esteem, and the results of the correlation of the two. Issues related to the presence of an ideal figure size in society are also discussed. A longer form of discourse analysis was involved for the readings of the women's accounts of having been teased about their appearance. These readings showed many women located their accounts of teasing within a discourse of trivialisation-of-teasing, indicating that the seemingly trivial practice of teasing is a powerful form of social control, resulting in feelings of vulnerability. The study concluded with summaries and conclusions from the literature presented in the introductions of both parts one and two. The quantitative and qualitative research methods were compared to see what both could offer body image research. Finally speculations were made about directions which body image research could take at both the individual and cultural level.