Lesions were placed in several areas of the telencephalon and diencephalon of the brain of the pigeon and the effects on the acquisition of inhibitory dimensional and inhibitory stimulus control were observed. The experimental tasks consisted of both visual and auditory interdimensional discriminations each of which had two components: In the first the stimuli were presented successively on the one response key (the main key) according to a multiple variable-interval extinction schedule. In the second the multiple schedule still obtained but a changeover key was added which, when pecked, changed the main-key stimulus, together with its associated schedule of reinforcement, to the next in a randomly ordered series. The use of these two components allowed the separation of two aspects of inhibitory control in learning: response reduction and stimulus reduction thereby permitting the assessment of discriminative ability in the absence of the confounding factor of response reduction. Inhibitory dimensional and inhibitory stimulus control were assessed by post-discrimination generalization tests and combined-cue tests, respectively. It was found that lesions to areas considered limbic - hippocampus, septum, anterior dorsomedial thalamus - had no effect on the learning of a visual discrimination. Lesions to the dorsolateral thalamus produced a complete inability to learn this discrimination, presumably due to disruption of visual fibres en route to the telecephalon. Lesions to the Wulst produced a visual discrimination learning deficit in some birds but not in others, an inconsistency not accounted for by differences in lesion size. Wulst lesions also produced an auditory discrimination learning deficit and in this case the larger the lesion, the larger the deficit. Lesions to ectostriatum produced a deficit in the visual task and lesions to Field L, an auditory projection area, produced a deficit in the auditory task, but not in the visual task. However, in most cases the discrimination learning deficit which was produced was confined to the multiple schedule where the animal had no control over the presentation or duration of the stimuli. Once the changeover key was introduced most birds obtained the learning criterion very quickly by "switching out" of the negative stimulus. This effective changeover responding, together with unimpaired inhibitory dimensional or inhibitory stimulus control, suggested that although the initial learning deficit might be described in terms of an inability to withhold responding in the presence of stimuli previously correlated with reinforcement, this inability could not readily be explained in terms of a lesion-induced impairment in an inhibitory process.

Young drivers have high rates of injury in New Zealand and throughout the Western world. It is commonly perceived that a major reason for this is their tendency to engage in unsafe driving behaviours, something that has frequently been labelled ‘risk taking’. A study of the literature suggested that the term ‘risk taking’ has been used in a variety of different ways and may have obscured our understanding of young people’s motives. Theories and research reviewed on the causes of unsafe driving behaviour amongst adolescents revealed a variety of potential contributors, ranging from the individual to the social. There is little evidence to implicate young women as unsafe drivers, who are most at risk as passengers. A survey of sixth form students (n=626) found high levels of unlicensed driving, breaking the rules associated with a restricted licence, failing to wear a seat belt in the back seat, speeding and being the passenger of a drinking driver. In addition, the survey found significantly more males than females reported: driving, engaging in unsafe driving behaviours, drinking and driving, speeding on the open road, breaking the night curfew associated with being on a restricted licence and dangerous thought patterns. Females were more likely to have been the passenger of a drinking driver after the last party they attended. Interviews with a sub-sample of those surveyed (n=16) revealed a number of scenarios that led to unsafe driving. These included: peer group dynamics, the adolescent sub-culture, emotional stress, an apparent lack of awareness of risk, and practical considerations. The interviews also indicated a lack of policing of the rules associated with the Graduated Driver Licensing System (G.D.L.S.). Interventions aimed at changing the behaviour of young drivers are examined and driver education is looked at in some detail. Problems with methodology made it difficult to reach clear conclusions about the efficacy of past programmes. Health education literature was analysed to ascertain what may be the ingredients of effective programmes for driving safety. An intervention study was carried out that compared a group of sixth form students who received a programme for driving safety (n=176) with a control group (n=146). Measures of attitudes, knowledge and self-reported behaviours yielded no significant differences between the two groups in either the post-test or the follow-up. A variety of reasons for this outcome are put forward, including the programme’s emphasis on thinking processes and its low fear approach. The recommendations that are made for decreasing the teenage road injury rate include: better policing of the G.D.L.S., education programmes and media campaigns that focus on the young male’s sense of personal immunity from risk, and increased availability of safe transport on occasions when young people are drinking. It is stressed that comprehensive safety plans that target all age groups are likely to have the greatest impact.

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 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.

The research reported in this thesis sought an explanation for the order of premodifiers in English nominal phrases. It aimed to establish what validity there is in the quite divergent earlier explanations, to find any other valid forms of explanation that might exist, and to integrate them all. The method was to make a wide survey of as many varieties of current English as possible, by observation; to then analyse the order at all levels (semantics, syntax, and so on); and to check the accuracy of the results against the 100-million-word British National Corpus. From that research, the thesis asserts that parts of most past approaches can be integrated into a comprehensive explanation; and that there is a new and important element of the full explanation, namely that of words' semantic structure, which is the combination of types and dimensions of meaning that make up the sense of each premodifier. Other new elements in this treatment of the subject are analysis of long groups of premodifiers (up to 10 words), consideration of why premodifiers regularly occur in different positions in the order, and explanation from the historical development of premodifier order. After an introductory chapter and a survey of the relevant literature, the thesis argues that the explanation of premodifier order in English nominal phrases is as follows. There are four positions for premodifiers, as in "your (1) actual (2) tinny (3) round (4) percussion instrument" [i.e. a tambourine] (chapter 3). The regular, unmarked order (illustrated in the phrase just quoted) has several elements of explanation: primarily, the semantic structure (chapter 4); secondarily, the syntactic structure (chapter 5). In a second type of order (when two or more words occur in one position), stylistic considerations control the order, not grammatical ones (chapter 7). In a third type of order, a marked one, a premodifier may be put in a position different from the position that the word's usual semantic structure would require, changing its meaning and stylistic effect (chapter 8). Some features of all three types of order are to be explained partly by their historical development - for example, the existence of borderline uses (chapter 9). There are some supporting explanations, from discourse structure and psycholinguistics, for example (chapter 10). The relevance of the previous chapters to wider issues, such as grammaticalisation, is discussed (chapter 11); and conclusions are drawn (chapter 12).

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.