“[The] sense of sameness is the very keel and backbone of our thinking” (James, 1890). To make sense of the ever-shifting information in our environment, we constantly assess whether the world around us changes or not, if objects are the “same” or if they are “different”. This basic decision-making process is found from the lowest level of cognition (e.g. when contrasts are encoded by the retina), to the highest (e.g. when comparing concepts), and anywhere in between. In an experimental context, this process is studied with the “same-different” task, where subjects are asked if two stimuli presented sequentially are strictly identical or not. This experiment has been documented since the 1960s and its results have been replicated with diverse stimuli types (letters, shapes, faces, words, etc.). However, every attempt to model the subjects’ accuracy and response times on correct and incorrect answers simultaneously was unsuccessful so far. Part of the challenge in explaining this task is that “same” answers are faster than expected compared to “different” answers, a phenomenon called the “fast-same effect”. This thesis aims to assess whether a formal model based on the inhibition of “different” answers is plausible, effectively changing the problem from “fast-same” to “slow-different”. In the first chapter, I review the previous theories and models of the same-different task to learn why they failed. By elimination process, I identify the only cognitive architecture that seems congruent with the data. I then propose a model prototype based on the inhibition of “different” answers that implements this architecture. In the second chapter, I test this prototype with an experimental paradigm designed specifically to assess its plausibility. I conclude that resources should be spent in developing a formal model based on the inhibition of “different” answers, as the prototype’s qualitative predictions are confirmed by both the typical same-different data and the newly acquired data.

The aim of the present study was to determine how lymphokines could exert their biological action on the skin during the course of the delayed hypersensitivity reactions. Four groups of experiments were conducted to investigate: (1) The production and the separation of lymphokines, (2) the protease activity of lymphokines and the effect of lymphokines on the kinin-forming system, (3) the effect of lymphokines on mast cells and platelets, and (4) the effect of enzyme-treated lymphokines on the skin inflammatory reaction. Guinea pig lymph node lymphocytes, stimulated by either the specific antigen DNP-BGG or by concanavalin A, were used to generate lymphokines. Parameters for testing lymphokine activities were those of migration inhibitory factor (MIF) and skin reactive factor (SRF). Separation of MIF and SRF from the lymphokine preparation by gel filtration, electrophoresis and fractional precipitation with ammonium sulphate was unsuccessful, which indicated that the physical properties of MIF and SRF were similar. Lymphokine preparations contained little or no neutral and acidic protease activities. / Medicine, Faculty of / Pathology and Laboratory Medicine, Department of / Graduate

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This research examined life events that affect the onset of delayed Post-Traumatic Stress Disorder in aging combat veterans. A common result from experiencing combat trauma is Post-Traumatic Stress Disorder. There is a rapidly growing veteran population experiencing delayed onset Post-Traumatic Stress Disorder. The occurrence of additional life stressors may increase the likelihood that someone will develop Post-Traumatic Stress Disorder in response to a prior traumatic event. Participants of the study were combat veterans over the age of 65. Qualitative data were gathered from interviewing participants on life events they have experienced since combat exposure as well as Post-Traumatic Stress Disorder symptoms. Findings suggested that life events contribute to the delayed onset of Post-Traumatic Stress Disorder in aging combat veterans. Understanding the development and causes of delayed Post-Traumatic Stress Disorder will help social work practice develop and move forward with programs to improve the quality of life for aging veterans.

Male birds of many species use conspicuous song and plumage displays in both courtship and territorial interactions. In some species, one or both of these signalling traits may not reach full adult maturity until a male’s second year of life. While the prevalence of delayed plumage maturation is well documented, delayed song maturation may be more difficult to detect. As a result, there are few studies which report age-based song differences between first-year and adult males. Additionally, despite the potentially large degree of variation of each trait within yearling males, little work has examined the benefits for young males who appear or sound more adult-like. Here, I investigate variation in both song and plumage displays of yearling male American redstarts (Setophaga ruticilla) as they relate to success during the breeding and non-breeding seasons. I first demonstrate a relationship between the degree of adult-like black plumage and both non-breeding season habitat quality in Jamaica and breeding season arrival date in Ontario. Previous studies have linked breeding season arrival date with winter habitat quality in adult males using stable-carbon isotope analysis. Together, these results suggest that variation in yearling male appearance may signal an individual’s competitive ability for high-quality resources. Next, I quantified the mate-attraction songs of both adult and yearling males and demonstrate a delayed maturation in this song type. I also present evidence of the potential benefits of expressing a more adult-like song by linking song structure with reproductive success in adult males. Finally, I demonstrate a potential relationship between the degree of adult-like song and plumage expression in yearling males, but not adult males. This work demonstrates that the delayed maturation of sexual signals may play an important role in the life-history of yearling male American redstarts, and highlights the need for in-depth analyses of individual variation of multiple sexual signals in this poorly-studied age class of birds. / Thesis (Master, Biology) -- Queen's University, 2009-09-25 10:42:19.794

Thesis--Copenhagen. / Summary in Danish. Bibliography: p. [109]-120.

Thesis--Copenhagen. / Summary in Danish. Bibliography: p. [109]-120.

Convergent validity has been used to evaluate the correlation between measurement tools. Delayed discounting has been used in order to determine the impulsivity in a variety of populations. Delayed discounting tasks have historically consisted of long, time consuming surveys. These tasks present participants with questions that relate to smaller sooner, or larger later rewards following various temporal delays. The purpose of the present study was to determine the convergent validity between a brief delayed discounting survey and a long, traditional version of the survey. The traditional survey consisted of 189 questions that contained 7 temporal delays and hypothetical money amounts. The brief survey was created based on the long survey but consisted of only 7 questions. Results from this study indicate that convergent validity did not exist between the two surveys. Keywords: delayed discounting, convergent validity, impulsivity

Research on impulsivity has focused on the choices between sooner, smaller stimuli versus larger later stimuli. More recent methods that have studied health choices compared temporal and probability discounting tasks between control groups and a comparison group such as smokers, obese individuals, alcoholics, etc. While correlations have been derived between responses on discounting tasks and selection of actual monetary reinforcers, research has not been expanded to question choices pertaining directly to the targeted problem. A technology that reliably assesses choices directly related to these illnesses has yet to be developed. The current study attempted to expand on the technology of discounting by applying it to choices related to healthy eating. 11 participants completed a cross commodity health discounting survey and average proportion area under the curve (AUC) was calculated for survey 1 (M = .41) and survey 2 (M = .21) Correlations between weight and proportion AUC (r = 0.69), income and proportion AUC (r = -0.32), and age and proportion AUC (r = -0.40) were determined. Methodological error that altered 2 variables (hypothetical weight and weight loss option) between surveys limited direct comparisons between survey. Implications of data derived from such error were discussed.

Master of Science / Department of Agronomy / Kraig L. Roozeboom / Interest has grown regarding management options to improve and stabilize dryland corn production (Zea mays L.) in challenging environments. Grain sorghum (Sorghum bicolor L.) has been documented to produce more consistent grain yields than corn in dryland production in Kansas. In periods of reduced water availability, sorghum can delay growth and development, allowing the plant to capture water later in the season for flowering and grainfill. Delaying planting in corn can serve a similar purpose. In central Kansas, planting corn earlier so pollination occurs before periods of extreme stress has been successful, but little research has investigated delayed planting or its long-term effect. The objectives of this study were to evaluate plant growth and yield response to delayed planting through field research and to quantify its long-term effects through crop model simulations. Field trials with delayed planting dates and hybrids of varying maturity revealed that yield at Manhattan, KS, did not decrease significantly until the final planting date in 2007 and did not decrease at all with delayed planting in 2008. At Belleville, yield increased with later planting in 2007 and was not affected by planting date in 2008. At Hutchinson, yield decreased significantly with each planting date until the third in 2007. However, in 2008, yield increased significantly from the second to fourth planting dates. Simulations in CERES-Maize over 51 years revealed no difference in yield between planting dates at Manhattan and Belleville, but showed a significant decrease between the first planting date and the third and fourth planting dates at Hutchinson. Chi-squared tests indicated that all planting date x hybrid combinations at Manhattan and Belleville produced economically profitable yields at frequencies significantly greater than 0.5. At Hutchinson, all but two of the twelve planting date x hybrid combinations produced profitable yields at frequencies significantly less than 0.5. The two remaining combinations produced profitable yields at frequencies that were not different than 0.5. One of these combinations was observed at the fourth planting date. These results suggest that the economical viability of delayed planting of corn is heavily dependent on location.