No description available.

Biological motion perception, defined as the ability to retrieve information from minimal displays of animal motion, has often been discussed as though it represents a single mechanism. However, depending on the task and details of the stimuli, there have been divergent results as to whether this ability is primarily based on motion or form processing, whether it relies more on local or global information, and whether the knowledge that is applied is learned or innate. These results can be reconciled by a multi-component framework, with five major components: local motion invariant processing, structure-from-motion, figure-ground segregation, action categorization, and style recognition. Several experiments are reported that are motivated by this framework. To investigate the sensitivity of the visual system to local motion invariants, performance was tested on a direction discrimination and a detection task with a point-light walker based on real motion-capture data or a synthetic walker created by Cutting (Chapter 2). When the walkers were displayed normally, performance was equal for both stimuli. However, when the walkers were spatially scrambled, the direction could only be determined for the natural walker, demonstrating that the invariant is found in subtle features of the local motion trajectories. Another experiment examined the difference in attentional distribution due to the task requirements (Chapter 3). Participants looked more often at the feet in a direction task than they did in a gender task, lending support to the idea that useful information can be derived from the local motion of the feet. Finally, Chapter 4 describes a battery of psychophysical tests that assesses each of the components of biological motion perception as independently as possible. The fact that individual performance does not correlate between tests is evidence that they measure different underlying mechanisms, supporting the multi-component framework. In the concluding chapter, multi-component computational models of biological motion perception are evaluated within this framework, and the evidence relating the components to activity in particular brain regions is reviewed. / Thesis (Ph.D, Psychology) -- Queen's University, 2011-05-27 09:25:30.774

This study has taken a problem solving approach in identifying the cognitive processes involved in designing computer-based instruction. The problem space essentially contains considerations of instructional goals and constraints, technological resources, and theoretical considerations. The problem space was augmented by an analysis of the strategic processes relevant in instructional design, in particular planning, and by an analysis of one specific technological resource, HyperCard. Concurrent think-aloud verbal protocols and computer operations protocols (video recordings of the users' interactions with the computer) were gathered from three university students enrolled in an educational technology course on developing courseware. Subjects were using HyperCard to develop instructional environments for individual course projects. The transcribed protocols were analyzed using a coding scheme based on the instructional-design problem space and planning model. Two types of analyses are reported: proportions of segments concerning different types of design and planning operations and descriptive representations of overall protocol goal structures and plans. (Abstract shortened by UMI.)

<p> Whether neural substrates underlying conflict resolution, or the ability to choose an appropriate response from number of alternate options, are shared across disparate domains is currently unclear. This thesis sought to extend previous studies examining this question by asking whether conflict adaptation occurs between Stroop (a non-syntactic task well-studied in the conflict resolution literature) and two different language tasks. Evidence for bidirectional behavioral interaction between processing of sentences with syntax-semantic conflict and Stroop was found in Experiment 1; however, there were no behavioral interactions between a multiword production task and Stroop in Experiment 2. The difference between these two studies could be consistent with either a domain-general or domain-specific model of conflict processing, as it is unclear whether interactions were not found due to differences in levels of conflict processing or differences in domains of conflict processing. Further research should focus on better distinguishing between these two possibilities. Finally, we also suggest that future research should better characterize the time course of conflict processing.</p>

<p> Contextual fear conditioning involves pairing a novel context (conditioned stimulus) with several footshocks (unconditioned stimulus) that serve to condition fear to that context. As the retention interval between training and testing increases context specificity is lost. In other words, the fear memory is no longer precise or context-specific, but has generalized to novel contexts at remote time points. In an attempt to investigate the neural pattern of an imprecise contextual memory trace as a function of time, we used fluorescent in situ hybridization to for Arc mRNA as a measure of neuronal activation following expression of a precise vs. imprecise context fear memory. Expression of a contextually precise memory involved increased Arc mRNA expression in both the dorsal and ventral CA1 regions of the hippocampus as well as the ACC and IL. Expression of a contextually imprecise fear memory involved Arc mRNA expression in the ventral CA1, ACC, IL, and the PL suggesting that both the hippocampus and prefrontal cortex are involved in the expression of a remote contextually imprecise memory. Further, inactivation of the ACC at remote time points returned the context memory to a precise state, but had no effect on memory for the training context. Taken together, these data suggest that as a context fear memory ages, both the hippocampus and prefrontal cortex interact in the expression of the memory trace resulting in the loss of precision. Preventing this interaction through inactivation of the ACC allows the hippocampus to express the contextually precise memory. In addition to the systems investigation of fear generalization, we also investigated a potential synaptic mechanism of the phenomenon. Specifically, we discovered that mice lacking a GABAB1 receptor subtype, GABAB1a, exhibit a loss of context discrimination compared to wild-type animals. Animals lacking GABAB1a receptors showed a significant, but not complete loss of context specificity 24 hours post-training. GABAB1a knock out mice exhibited a complete loss of context discrimination by 5 days post-training. However, knock out mice exhibited normal context discrimination immediately following training, suggesting that GABAB1A receptors are necessary for the retention, but not acquisition, of context discrimination. Our results indicate that presynaptic inhibition is required for the maintenance of context. </p>

Social phobia is the fear that one’s behavior in a social situation will be inappropriate and will lead to humiliation and rejection. The purpose of this study was to learn more about how individuals with social phobia direct their attention when they are experiencing social anxiety. Previous research shows that such individuals focus their attention on negative self-evaluation during a feared social event, while other research shows that an individual with social phobia focuses on picking up negative cues in the environment during a stressful event. Fifty participants from a region in Southern California completed the study. Participants completed a computer task in which targets to be identified were preceded by negative or neutral social cues. Participants were then given an anxiety induction before completing another block of the computer task. Results showed that neither level of social anxiety nor manipulation of anxiety affected performance on the computer task. Regardless of social anxiety level, all participants showed slower reaction times when prompted with a negative social cue whether at the target location or elsewhere. Future research should explore the effects of negative social cues on attention.

The series of studies reported in this thesis aimed to improve our knowledge of the cognitive disturbance in anorexia nervosa and bulimia nervosa. Techniques from experimental cognitive psychology were used to test predictions made by cognitive theories of eating disorders. In the first study, subjects performed three tasks related to eating, weight and shape and self-statements were measured using concurrent verbalisation and a selfreport questionnaire. Compared to dieters and non-dieting controls, patients with bulimia nervosa showed greater concern with weight and appearance while patients with anorexia nervosa showed greater concern with eating. In the second study, using an adaptation of the Stroop colour-naming task, patients with eating disorders showed greater selective processing of information related to eating, weight and shape than normal, non-dieting controls and normal dieters. In the third study it was found that this disturbance was more closely related to measures of the specific psychopathology of eating disorders rather than to measures of general psychopathology. In the fourth study information processing before and after treatment was compared. As predicted by cognitive theories, selective processing appeared to be related to the emotional salience of the clour-named words rather than to patients' familiarity with the issues represented by these words. In the fifth study information processing before and after three different psychological treatments for bulimia nervosa was measured. No support was found for the hypothesis that cognitive behaviour therapy operates through mechanisms specific to this treatment. Contrary to predictions, in the sixth study, when colour-naming was measured at the end of treatment and at 12 month follow-up, selective information processing did not predict relapse in symptoms of bulimia nervosa. Finally, a seventh study, which manipulated attitudes to eating, weight and shape experimentally, found evidence for a causal relationship between these attitudes and disturbed eating behaviour. Methodological issues, and the clinical and theoretical relevance of the research findings, are discussed.

In this thesis a cognitive-behavioural model of health anxiety is used to investigate the psychological effects of bone densitometry, a health test which can provide an indication of future risk for osteoporosis. The cognitive-behavioural model of health anxiety proposes that people will experience relatively high levels of anxiety about their health if they have a tendency to make particularly negative interpretations of bodily variations and information which may be relevant to health. It was therefore predicted that people who have a pre-existing tendency to worry about their health would react more negatively to the results of bone density measurement. Consistent with this prediction, after a low bone density ("high risk") result, women who reported high levels of pre-existing health anxiety gave higher ratings of anxiety about osteoporosis and perceived likelihood of developing osteoporosis in the near future than women with low levels of preexisting health anxiety. (The two groups did not differ significantly in these ratings before the scan). Differences in the reactions of women with high and low levels of pre-existing health anxiety were still apparent 14 months after the scan. Women receiving a low bone density ("high risk") result showed a "minimization" of the seriousness of low bone density; when individual differences were investigated, it was found that women with very high levels of pre-existing health anxiety did not show minimization. Furthermore, after a "low risk" result, women with high levels of health anxiety were only temporarily reassured. It thus appears that the new measure of health anxiety which was used in this thesis may be useful in helping to identify people who are vulnerable to experiencing distress after health screening. More specific pre-scan measures of beliefs about osteoporosis (derived from the cognitive-behavioural model) also predicted reactions to bone density screening. For example, pre-scan beliefs about the seriousness or burden of low bone density / osteoporosis were stronger predictors of anxiety about osteoporosis three months after the scan than the actual scan result. Factors such as the type of interpretation the woman makes of her scan result, and whether the woman is having her first or second scan, were also found to influence psychological reactions.

No description available.

In order to clarify the relationship between anxiety vulnerability and clinical anxiety, information-processing models have been employed to examine the cognitive biases of anxious individuals for threat-related information. At the core of these models are research findings indicating that anxiety-linked attentional biases render high trait anxious individuals disproportionately vulnerable to the effects of stress. The current research, following the model of Williams, Watts, MacLeod, and Matthews (1988), tested the hypothesis that attention to threat-related information is due to the interaction of trait anxiety and state anxiety. / Five comparable studies employed emotional Stroop and probe-detection paradigms to assess the attentional biases of high and low trait anxious individuals to threat-related words in response to elevations of stress. Four of the studies assessed the preconscious and conscious attentional biases of adults and one study investigated the attentional biases of children. This focus allowed developmental comparisons that had not been undertaken previously. The studies were comparable to each other and to previous research. The studies sought to clarify the effects of different forms of stress on the anxiety-linked attentional biases and to assess the effects of these stressors on domain-specific stimuli. The hypotheses were that, in response to elevations in state anxiety, high trait anxious individuals show increased attention to threat and low trait anxious individuals show avoidance of threat. It was expected that these threat-related attentional biases are identified at both preconscious and conscious levels of processing, and more when the stimuli are related to the individuals’ domain of concern. / Contrary to expectations, only one study found the predicted pattern and this result occurred at a conscious level of processing. In addition to the lack of support for the hypotheses, a counter-intuitive alternative pattern that was the converse of predictions was identified in four of the five studies. In this pattern, in response to elevated stress, there was a trend for high trait anxious individuals to show decreased attention to threat and low trait anxious individuals to show increased attention to threat. The pattern was identified, in various studies, at conscious and preconscious levels of processing, and more in response to domain-specific stimuli. Adults and children showed similar levels and types of attentional biases. / The results of the current studies show some convergence with previous research. The findings are discussed in the context of a proposed model that incorporated aspects of Williams et al’s theories (1988; Williams, Watts, MacLeod, & Mathews, 1977) and Mogg and Bradley’s (1988) theory. This model suggests that high and low trait anxious individuals’ patterns of threat-related attentional biases vary according to their different levels of reactivity to stress, which affects their threat threshold. Due to differences in this threat threshold, high and low trait anxious individuals show divergent attentional responses under the same level of external stress. The model incorporates the avoidance effects identified in previous research and theory. This model may explain both the current counter-intuitive findings and past inconsistencies in the literature. It may also clarify how individuals with different levels of anxiety vulnerability show divergent attentional responses to stress elevations. It is suggested that inclusion of the notion of subjective stimulus threat value into the cognitive processing paradigm may clarify some of the unresolved issues raised in this research.