Honors Theses


Erin O’Mara, Ph.D.



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Honors Thesis


The current longitudinal study was conducted to test if people perceive their physical body size to be smaller than it is, and if people do self-enhance their body size, then how do body self-enhancement and stress interact to predict subsequent Body Mass Index (BMI). This study toke a biopsychosocial approach to understanding why people make health decisions by measuring participants’ self-enhancement, perceived stress, cortisol baseline levels, and stress reactivity and observing their associations and interactions with subsequent weight gain. Self-enhancement is a type of positive illusion characterized by overly positive attitudes people have towards themselves, which is used for promotion and maintenance of a positive sense-of-self. Previous research has found that people’s self-enhancing tendencies about their traits and abilities extended to automatic and perceptual judgments of themselves by perceiving themselves as more attractive than they are (Epley & Whitchurch, 2008). The current study questions if this also applies to body size. Additionally, different types of stress were measured, such as perceived stress using the Perceived Stress Scale, as well as baseline cortisol levels and stress reactivity. Saliva samples were collected before and after an acute stressor, the Trier Social Stress Task (TSST), and analyzed using Salimetrics ELISA Cortisol Kit (Birkett, 2011; Kirschbaum, Pirke, & Hellhammer, 1993). TSST was recommended by Dickerson and Kemey’s (2004) meta-analysis as an acute stressor that accurately and validly activates the HPA axis, the central stress response system responsible for releasing cortisol (the stress hormone). Previous studies support two conflicting hypotheses about the health implications of selfenhancing (Taylor et al, 2003). The results of this study show that participants do self-enhance their body sizes to be smaller than they are and that there are significant associations between body self-enhancement and BMI, mediated by stress that support and contradict previous hypotheses on the health consequences of self-enhancing.

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Undergraduate research



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