The present study sought to investigate the combined influences of degree of first-list learning, stimulus order, emphasis, and meaningfulness on the selection strategies of college subjects.

Cue-controlled relaxation is looked at to determine whether a component is efficacious as the entire procedure. Subjects were 40 male and 40 female undergraduates. Subjects were randomly assigned to one of four conditions: cue-controlled relaxation, progressive muscle relaxation, breathing exercises with a paired. cue word, on a presentation of the cue word without being paired. It was hypothesized that cue-controlled relaxation would be superior to a component of cue-controlled relaxation. It was determined that cue-controlled relaxation is not more efficacious than a particular component. Data suggests the majority of anxiety reduction takes place when the treatment focuses on the same modality from which the subject receives the most information about their anxiety. Implications and suggestions for further research are presented.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

The human visual system gathers information about three-dimensional object shape from a wide range of sources. How effectively we can use these sources, and how they are combined to form a consistent and accurate percept of the 3D world is the focus of much research. In complex scenes inter-reflections of light between surfaces (mutual illumination) can occur, creating chromatic illumination gradients. These gradients provide a source of information about 3D object shape, but little research has been conducted into the capabilities of the visual system to use such information. The experiments described here were conducted with the aim of understanding the influence of chromatic gradients from mutual illumination on 3D shape perception. Psychophysical experiments are described that were designed to investigate: If the human visual system takes account of mutual illumination when estimating 3D object shape, and how this might occur; How colour shading cues are integrated with other shape cues; The relative influence on 3D shape perception of achromatic (luminance) shading and chromatic shading from mutual illumination. In addition, one chapter explores a selection of mathematical models of cue integration and their applicability in this case. The results of the experiments suggest that the human visual system is able to quickly assess and take account of colour mutual illuminations when estimating 3D object shape, and use chromatic gradients as an independent and effective cue. Finally, mathematical modelling reveals that the chromatic gradient cue is likely integrated with other shape cues in a way that is close to statistically optimal.

A number of theories have attempted to explicate mechanisms underpinning the transition from recreational drug use to substance dependence. A highly reliable correlate of dependence is the value ascribed to the drug. However, supernormal drug valuation may be insufficient to fully account for a subgroup of dependent individuals for whom the course of dependence is chronic and relapsing and who persist in drug use in the face of devastating costs. Three candidate secondary mechanisms for dependence are considered in this thesis: cue reactivity, cost discounting, and sensitivity to negative affect. Neither cue reactivity nor cost discounting were found to be significantly associated with severity of alcohol dependence in samples of young adult drinkers. By contrast, induced negative affect was found to be reliably associated with augmented alcohol motivation, and sensitivity to this effect was related to symptoms of depression and self-reported drinking to cope with negative affect: both risk factors for the development of dependence. These findings delineate a particular subset of dependent individuals for whom negative affect may represent a substantial trigger to continued drug use. There are a lack of brief interventions to abolish or limit negative affect driven drug motivation. This thesis trialled three potential interventions. A natural walk intervention in hazardous drinkers showed no evidence of limiting this effect in two experiments. Brief instruction in acceptance-based coping showed no evidence of limiting annoyance in response to an aversive noise induction procedure in an alcohol dependent population, and was therefore also eliminated as a potential intervention. However, engagement with pleasant environmental images, as a proxy for environmental enrichment, significantly reduced negative affect driven alcohol choice in student drinkers who reported a desire to visit the locations shown (high liking), compared to low-liking individuals and controls. This provides preliminary evidence for the efficacy of environmental enrichment type interventions, justifying further trials. In treatment of dependence more generally, interventions to increase access to healthy, non-drug sources of positive reinforcement may prove effective.

Coral reef fish larvae take an active role in selecting their settlement site and sensory cues may help them to orientate during this process. As settlement is a period of transition through which the majority of individuals do not survive, it is often a focal point for the management of coral reef populations, which are of high conservation concern. In this thesis, I used choice tests and in situ techniques to assess the response of settlement-stage larvae to a range of odour, light and acoustic cues and I found that larvae are more selective in their response to sensory stimuli than previously thought. Micro-habitat odours are not likely to be used during settlement orientation, and odour cues may be used to avoid inappropriate settlement sites. The photopositive behaviour of larval fish is likely to match their spectral sensitivity but this proved difficult to assess in situ because of the high amount of spatial and temporal variation in larval distribution. The positive response of settlement-stage fish to played back reef noise is location specific as well as being highly specific to the reef sound recording. To understand whether it might be the composition of reef sound that drives the selective response of larvae to acoustic cues, I took sound recordings while collecting visual data on fish diversity and the behavioural activity of a sound producing, or soniferous, fish species. I found that the variation in intensity of reef noise matches the activity patterns of a soniferous species, and when reef noise is most intense is when visual estimates on the diversity of the reef fish assemblage are decreased. This information provides the basis for understanding how changes in the reef soundscape may effect larval recruitment and has exciting implications for using sound recordings as a method to monitor coral reefs. Finally, I tested the viability of releasing reared larvae to boost depleted populations and found that collecting and holding settlement-stage fish for a week can increase survival, relative to natural settlement. These data demonstrate that applying our knowledge of the settlement behaviour of coral reef fish will make a significant contribution to developing tools for management.

Smoking is now the leading cause of preventable death and disease in women. Understanding women's motivations to smoke is important in developing effective cessation and relapse prevention programs. Previous descriptive, correlational, and quasi-experimental research has established that weight concerns and negative body image are associated with tobacco smoking, cessation, and relapse, particularly among young women. This study, building upon a previous experimental study (Lopez, Drobes, Thompson, & Brandon, 2008), examined whether activation of negative body image cognitions would produce greater urges to smoke and would affect actual smoking behavior. A randomized 2 X 2 crossed factorial, between-subjects design (body image manipulation X smoking cue manipulation) was conducted with 133 female college smokers. The body image manipulation involved trying on a one-piece bathing suit or evaluating a purse, and the smoking cue manipulation included the presentation of their pack of cigarettes or a stapler. Participants completed pre-intervention measures assessing smoking history, trait body dissatisfaction, trait self-objectification, and trait affect. State levels of urge to smoke, mood, and body dissatisfaction were assessed after the manipulations. It was hypothesized that main effects on the measures of smoking motivation (i.e., self-reported urges to smoke and topographical measures of smoking behavior) would be found for the body image manipulation, with trait body dissatisfaction and/or trait self-objectification moderating the body image manipulation and state negative affect serving as a mediator. Results indicated that trying on a bathing suit, which increased body dissatisfaction, did increase reported urges to smoke, particularly those urges related to reducing negative affect. Women assigned to the bathing suit condition also subsequently took a greater number of puffs from their cigarette than those who evaluated the purse. (No main effects were found for the smoking cue manipulation). No moderation effects were found, but the effect on smoking urges by the body image manipulation was mediated by state negative affect. This study provides additional support, through an experimental design, that situational challenges to body image influence smoking motivation, and that this effect occurs, at least in part, via increases in negative affect. Theoretical and applied implications are discussed.

During the development of the nervous system, a complex system of chemical and mechanical cues guide nerve cell projections toward appropriate targets by eliciting attractive or repulsive responses from navigating structures called growth cones. Current in vitro models of neural guidance lack the capacity to provide multiple cues within the same substrate. This dissertation presents in vitro models with tunable presentation of multiple chemical and mechanical guidance cues in a single substrate for elucidating a more complete understanding of growth cone responses to the extracellular environment. In the first study, our model utilized a light-sensitive agarose gel as the growth substrate and a polyethylene glycol gel that contained three dimensional neural growth in specific geometries. This model incorporated molecular cues as immobilized proteins and gradients of soluble factors in a quantifiable manner. The agarose gel presented issues with gelation and supporting neural growth, so we sought to improve upon our initial design by changing the growth substrate. The second study employed a novel light-sensitive dextran gel in place of the agarose of the first study. The chemoattractant neurotrophin-3 and chemorepellant semaphorin3A were immobilized within this dextran gel in a spatially defined manner, and the response from growth cones quantified. The growth cones did not respond to the control protein NeutrAvidin, exhibited a moderate response to neurotrophin-3, and showed a strong repulsive response to semaphorin 3A. The third study investigated neural responses to changes in substrate stiffness. Dextran gels with light-degradable crosslinks exhibited different elastic moduli based upon irradiation time. Specified regions of dextran gels were irradiated with light to present growth cones with a choice between two different elastic moduli. Growth cones exhibited preference for a narrow range of elastic moduli spanning less than 200 Pa, an observation unattainable with other in vitro models. The results establish our models as possible platforms for observing and manipulating specific growth cone responses to both chemical and mechanical cues. Understanding how the growth cone interacts with its environment may lead to improved wound healing therapies, and expanding our model into a high-throughput assay could contribute to the development of these new treatments. / acase@tulane.edu

Obesity is a growing problem in the United States. Research into the causes, treatment, and prevention of obesity is vital. One past study examined four eating behaviors in relation to obesity: eating beyond satiety, snacking, night eating, and feeling hungry within three hours of eating. Only eating beyond satiety was associated with obesity. The present study examined these same eating behaviors while correcting some of the flaws of the previous study. Using a cross-sectional design, university undergraduates reported on the frequency of the above-named eating behaviors. Current weight and height were collected. Multiple regression analyses determined that eating beyond satiety and hunger predicted body mass index (BMI). Race/ethnicity moderated the relationship between hunger and BMI. These findings have important implications for obesity treatment as well as suggesting important avenues for future research.

Smoking is now the leading cause of preventable death and disease in women. Understanding women's motivations to smoke is important in developing effective cessation and relapse prevention programs. Women, more so than men, appear to associate their smoking behavior to issues of weight. Although a general relationship between weight concerns and smoking has been found among women, a causal relationship had not been demonstrated. This study tested whether activation of negative body image cognitions would produce greater urges to smoke and whether the relationship would be moderated by trait body dissatisfaction and mediated by state body dissatisfaction. A randomized 2 X 2 crossed factorial, within-subjects design (body image cues X smoking cues) was conducted with 62 female college smokers. The body image manipulation comprised an image of either a thin model or a neutral object, and the smoking manipulation comprised an image of either a smoking cue or a neutral object. Participants completed pre-intervention measures assessing smoking history and body image dissatisfaction. Urge to smoke, mood state, and weight and appearance satisfaction were assessed during the experiment. It was hypothesized that main effects on reported urge to smoke would be found for both manipulations, with body dissatisfaction moderating the body image manipulation. Results indicated that both smoking cues and thin model images increased reported urges to smoke. Additionally, in the absence of smoking cues, the effect of the body image manipulation was moderated by baseline body dissatisfaction, with those women with greater body dissatisfaction reacting more strongly to the thin model image. The effect on smoking urges by the body image manipulation was partially mediated by both state measures of affect and body satisfaction. Thus,this study is the first to demonstrate through an experimental design that the presentation of images portraying thin women increased smoking urge, which is consistent with a causal influence of body image affecting their smoking motivation.