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.

No description available.

No description available.

The purpose of this study was to investigate the immediate consequences of concussion. Previous work had either concentrated on memory defects only, included cases of cerebral damage as well as concussion, or examined residual defects persisting after the period of impaired consciousness had ended. It was hoped to determine which function or functions might be affected in concussion by testing only young adult cases of 'pure' concussion in the immediate post-traumatic period. In the main experiment a paced serial addition task was administered to a mildly concussed (MC) and seriously concussed (SC) group at twenty-four-hourly intervals during the hospital period, and thirty to forty days after discharge. A normal control and hospital control group were given the task at similar time intervals. Recent concussion impaired performance and SC Ss needed almost five times as long as controls to process each correct response while MC Ss were about twenty per cent slower, However, responses were qualitatively similar in all groups, and concussed Ss differed only in producing many more late response errors. At retest the MC group had regained control level, but although SC Ss had significantly improved PASAT scores they were still poorer than the other three groups. Experiments II and III investigated stages in the information transmission process which may have produced restricted information processing shown by PASAT results. Reaction and movement times were not longer than normal, although central processing time was. MC Ss did not have significantly slower non-symbolic RTs, or symbolic two- and four-choice RTs, but they differed significantly from controls on eight- and ten-choice symbolic trials. Again this difference between groups was not found at retest four weeks later. Results suggested inefficient 'pigeon-holing' (Broadbent, 1971) as a possible factor in reduced information transmission following concussion. However, a message repetition task indicated no difference between concussed and non-concussed Ss in use of this mechanism. Message repetition also demonstrated that patients had no difficulty in auditory perception of verbal material. In the third stage, normal Ss were given message repetition with and without a concurrent distracting task. Performance during distraction was sufficiently similar to that of recently concussed Ss to suggest that the patient group may have been poorer than controls on the same task only because they also had reduced processing capacity. When given PASAT with a secondary paced task, performance of another group of normal Ss was almost identical to concussed Ss in the first experiment. Finally, to test the possibility that reduced processing capacity was the result of increased distractability, that is, processing task-irrelevant stimuli, an attention task (speech shadowing) was given to a small group of MC Ss and normal controls. There were no instances of intrusions or interference from an irrelevant message to indicate a defect in selective attention, although MC Ss had significantly lower shadowing scores. It was concluded that reduction in processing capacity produced by concussion was a function of patients' lower level of arousal, and that performance resembled that reported in the literature from sleep-deprived Ss and cases of brain-stem damage or dysfunction. A feature of results was the extremely competent performance exhibited by concussion patients, given a reduction in total capacity. Similar optimizing behaviour was evident during distraction tasks, and it was suggested that ability to monitor and control distribution of available processing space by instructions ('set') is a general characteristic of ordered behaviour. This ability was not disturbed by degrees of concussion sustained by experimental Ss in this study. Amnesic symptoms of the immediate post-traumatic period were considered in terms of lowered arousal level. It was proposed that these might be explained by a combination of two factors: (i) processing space insufficient to store items while responding to them, and (ii) tagging of items in storage with levels of concurrent background activity, and thus 'state-dependent' memory. Evidence for a processing deficit existing after termination of the period of PTA was reviewed, and the possibility of permanent effect in terms of increased disability following repeated concussions. Some aspects of results important in considering rehabilitation programmes for head-injured patients were noted.

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.

The measurement of behaviour by direct observation may be improved when observers have been provided with equipment which enables real-time recording. There are no data available concerning the quality of this type of measurement. Indeed, there is no consensus among researchers as to appropriate methods of quality assessment. In the present series of studies, observers were provided with hand-held computers programmed to act as real-time recorders. The quality of their records was assessed by three "traditional" methods, representative of those which have been used most frequently in previous behavioural research: interobserver agreement, observer/criterion agreement, and relative error. An instrument calibration procedure, the standard method for measurement accuracy analysis in the natural sciences and engineering, was demonstrated for comparison with traditional methods. The traditional methods were found to be unsatisfactory for theoretical and empirical reasons. The calibration procedure was shown to have some considerable potential advantages for applied behaviour analysis. Disadvantages, both statistical and practical, were also discussed.

The 1980s saw an increasing interest amongst psychologists, both as researchers and as practitioners, in the ways in which people react to nuclear weapons issues, especially the perceived threat of nuclear war. Much of the research in relation to "nuclear threat", undertaken either within the United States or by United States psychiatrists in collaboration with European colleagues, and using extensive questionnaire surveys, focused on the fears of children and teenagers. Some researchers concluded that large proportions of young people were at risk of impaired psychological development because of nuclear threat which resulted in a pervasive sense of futurelessness and a distrust of .adults. This research has been widely criticised since because of apparent researcher bias in the methods used, interpretations offered, and general paradigm. I also found much of the research ethically objectionable. My research has involved 52 interviews with young New Zealanders and administration of a questionnaire to more than 2000 others, including ages nine to 18 and three ethnocultural groups, as well as interviews with some teachers. The objectives of these studies were: (1) to produce detailed information about how young New Zealanders react to nuclear weapons issues which might be used by educationalists, mental health professionals, parents, and young people themselves in dealing with those issues; (2) to make specific recommendations about young New Zealanders' apparent needs and preferences for learning about and dealing with nuclear weapons and related issues; (3) to provide a detailed methodological comparison of interview and questionnaire approaches to this research topic, and discuss issues of theory and paradigm; and (4) to comment on ethical and practical issues for both the researcher and the researched in undertaking research on emotive and potentially distressing topics, especially with young people. As a result Chapter 1 of my thesis contains a comprehensive critical review of the international research and theory relating to young people's perceptions of nuclear weapons, examining the problems of method, interpretation and paradigm associated with this area of research. Both interview and survey data are presented in relation to: (a) young people's levels of awareness and sources of information about nuclear issues; (b) their emotional, cognitive and behavioural reactions to nuclear issues, including coping strategies and activism: (c) their perceptions of the future; (d) comparisons across gender, age and ethnocultural group; (e) the role of adults; and (f) differences between New Zealanders and other national groups. The data are discussed in terms of: (i) their patterns, contexts and meanings; (ii) their implications for peace and global issues education; and (iii) their implications for research method, including ethical issues. Recommendations are made for how psychologists and others can help young people and adults in dealing with global and social threats, including how to undertake research which is empowering as well as valid and useful.

Four experiments are reported. Each experiment investigated a different variable which at sometime has been thought to influence performance in multiple schedules. Variable-interval schedules were used in all experiments and twelve pigeons served as subjects, six in the first two experiments and six in the third and fourth. The parametric data provided by each experiment were analysed using the generalized matching law and comparisons with findings in concurrent-schedule research were made. In Experiment 1 the effects of component durations and component reinforcer rates on multiple-schedule performance were investigated. Component duration did not affect sensitivity to the ratios of reinforcer rates. In Experiment 2 the effects of food deprivation and component reinforcer rates on multiple-schedule performance were investigated. Sensitivity to the ratios of reinforcer rates increased as deprivation was reduced. However, the data could only be explained by a model which assumed no direct component interaction. In Experiment 3 the discriminability of the stimuli customarily used in multiple-schedule research was investigated. The stimuli were perfectly discriminable. It was shown that the undermatching of response and reinforcer ratios typical of multiple-schedule performance was not the result of a failure to discriminate the stimuli signalling the components. In Experiment 4, a procedure for investigating time allocation in multiple schedules was introduced. The birds could switch in to the component in effect, and the components alternated at three minute intervals. Each switch in to a component gave acess to the schedule in effect for fixed brief periods. Ratios of component response rates showed typical multiple-schedule undermatching. However, a commonality in concurrent and multiple-schedule performance was revealed in respect to local or switched-in response rates. In both types of schedule, it appears that pigeons allocate time so as to equalize the local response rates. It is apparent that the differences reported between concurrent and multiple-schedules with respect to the sensitivity with which responses are distributed between the components as a function of the distribution of reinforcers are a result of the constraints imposed on the subjects' allocation of time in multiple schedules.