Theses by Psychology Students

The Student Honors Papers collection represents exemplary work in psychology at Illinois Wesleyan University. The Ames Library is proud to archive these and other honors projects in Digital Commons @ IWU, the University's online archive of student, faculty, and staff scholarship and creative activity.

Examining the Evolution of Cognition Using a Breed Differences Approach
by Eric Rydell

Examining the effects of evolution on cognition presents both cognitive psychologists and evolutionary biologists with an extraordinary challenge: Cognition does not fossilize and is therefore difficult to track over evolutionary time. It is far easier to examine the effects of evolution on morphological changes, as these differences are physically apparent and easily observable in the fossil record. One way to observe the effects of evolution on cognition is to explore how known selection pressures shape cognition in related species yet this can lead to some confounding variables as different species also have different morphological or motivational mechanisms at work as well as cognitive mechanisms. We therefore examined the evolution of cognition through artificial selection of cognition traits in the domestic dog- a single species with breeds that have been selected by humans to perform specific behavioral roles. Different breed groups of dogs have been preferentially bred to succeed in different tasks, which help to generate intuitive predictions about which breed groups should succeed on some cognitive tasks and which groups should be less successful. We therefore conducted a self-control task: the cylinder task. In this task dogs mush inhibit their instinct to go directly towards food and must detour around a clear barrier to successfully achieve the food reward. We will demonstrate that although dogs are, as a whole, fairly successful with this task, variation in breed relates to variation in success at the cylinder task. We suggest that exploring breed differences in cognition in dogs can provide some insight into the evolution of cognition more broadly.

Predicting Aggressive behavior using Ego Depletion, Provocation and Dispositional Aggressiveness
by Grace Hanzelin

This study, based on the I-Cubed model behavior, examined situational factors which can contribute to the manifestation of aggressive behavior. Participants included 96 students from Illinois Wesleyan University. An E-Crossing task was utilized as an Ego- Depletion task to manipulate participants' levels of inhibition, negative feedback from an ostensible other participant was used to provoke participants and manipulate instigation, and dispositional aggressiveness- measures on the Buss- Perry Aggression Questionnaire- was used as the factor of impellance. Analyses indicated that the provocation of participants played a key role in predicting aggressive behavior, but Ego- Depletion did not significantly impact this prediction.

Effects of Affective State on Neural and Behavioral Indices of Social Exclusion
by Tanya Gupta

Some exclusion is a universal and relatable phenomenon, with far-reaching and deleterious effects. The scientific examination of the ongoing processing of exclusion using the continuous data provided by neural event-related brain potentials (ERPs) provides valuable insight regarding one's cognitive processing of exclusion and its psychological consequences. Although several ERP studies of social exclusion exist using the Cyberball paradigm, there is a lack of information regarding different forms exclusion, as well as exposure to factors prior to exclusion which may modify its detrimental neural effects. The current study utilizes the measurement of continuous neural data as well as self-report measures to examine the neural effects. The current study utilizes the measurement of continuous neural data as well as self-report measures to examine the neural effects of a novel ERP exclusion paradigm, called the Future Alone task. Further, the study employs the International Affective Picture System (IAPS) in order to observe the possible modification of ERP and self report responses to different forms of social exclusion by changing one's affective state. Results indicate that the Future Alone task can be used to elicit Feedback-Related and P300 ERP components, and that the amplitude of these ERPs is affected by overall inclusionary/exclusionary condition. Additionally, results show that affective state influences ERP responses to Cyberball exclusion, and that this difference is dependent upon both overall inclusion/exclusionary condition and inclusionary/exclusionary nature of the Cyberball throw.

Understanding the Influence of Social Networks and Social Roles on Individuals with Developmental Disabilities: Providing Opportunities in Order to Assess Quality of Life
by Brianna Piro

This study investigates the influence of social role opportunities on quality of life for individuals with developmental disabilities (DD). It also explores the impact of informal social networks on social capital for this population. This study analyzed the effects of newly created social role opportunities on quality of life for a small group of individuals with DD. The hypothesis suggested that those given a new social role would report a higher quality of life than those not given a new role. Pre-test/post-test interviews were administered and a 6 week intervention was implemented with participants of a local social group in order to assess quality of life. A Social Capital Index interview was also conducted to determine the social capital of the participants in the social group. In terms of social capital, the second hypothesis proposed that members of the social group would have more social capital than those who were not members of a social group. Results from this interview were compared to data from individuals who were not members of a social group in order to determine if informal social networks influence social capital. Nonparametric statistics were used, but no statistically significant findings were revealed. Despite the lack of significance, qualitative evidence aligns with previous literature and suggests that people with development disabilities share a common desire for more social role opportunities.

The Impact of Dexamethasone on Behavioral Development in Larval Zebrafish (Danio rerio)
by Casie L. Henrikson

Stress can have damaging effects on a developing organism. Cortisol, a glucocorticoid critical to the stress response, can readily permeate across the placental barrier, which may have long-lasting, deleterious effects on the stress response of the developing organism. The synthetic homologue of cortisol is dexamethasone (dex), a corticosteroid used as an anti-inflammatory drug in humans to treat various autoimmune diseases and cancer. Dex is also often given to preterm infants to accelerate fetal lung development prior to delivery. Research with animal models has linked prenatal dex exposure to increased fear reactivity, decreased loco motor activity, and elevated cortisol levels in response to stress, in addition to brain cell loss and neurodevelopmental disability. The present study used larval zebrafish (Danio Rerio) to examine the effects of dex exposure on anxiety-related behavior during a window critical for the devleopment of the Hypothalamic-Pituitary-Interrenal axis, a network of brain structures responsible for maintaining and facilitating negative feedback of the stress response. By varying exposure to dex (dex vs. control) and timing of exposure (0 to 12 hours vs 12 to 24 hours post fertilization), and examining the effect on motor behaviors in 5 day old zebrafish larvae, this study sought to advance our understanding of the mechanism by which prenatal stress may cause long-term changes in stress reactivity. Results did not support our hypotheses. There was no evidence of an effect for drug exposure or timing of exposure. There was, however, an unexpected interaction, such that larvae in the control condition presented the greatest changes in thigmotaxic behavior following the presentation of a novel stimulus.

The Effects of Good Limb Training on the Corpus Callosum in C57BL/6 Mice
by Ryan Holden

Previous research on rehabilitative strategies after stroke indicates that recovery strategies can promote long-term recovery of the impaired limb, whereas compensatory strategies produce detrimental effects on the impaired limb. In the present study, mice were separated into three groups: mice that received good limb training, mice that received bad limb training, and mice that received no training after stroke. The pasta matrix reaching task was used for training and to assess bad limb impairment. The present study investigated two hypotheses. First, we hypothesized that the mice receiving good limb training would show less functional recovery than the mice receiving either bad limb training or no training. Using an anterograde tract tracer (BDA), we also investigated the effects of good limb training recovery on the anatomical connections between hemispheres. As a result, our second hypothesis was that trainging the good limb during rehabilitation results in aberrant connectivity with fewer crossing fiber projections in the corpus callosum. The behavioral performance seen in previous literature was replicated in the present study. Furthermore, our results indicate there were no significant differences between the good limb and bad limb group in the number of cross-cortical fibers in the corpus callosum. Analyses of alternative brain regions are currently underway.

Dog Self-Control: The Extent and Limitations
by Stephanie M. AuBuchon

Self-control predicts positive and negative outcomes for humans (Mischel & Ebbesen, 1970). Self-control may not be uniquely human: several non-human primate species wait for a more preferred reward and forgo immediate less-preferred choices. However, little work has explored individual differences or limitations in self-control of non-primates. In the present study, nine dogs were presented with a spinning plexi-glass covered wheel. When the wheel spun, it brought food close to a window where the dog could access it. A less-preferred reward approached the window before a more-preferred reward. If dogs ate the first reward the wheel stopped spinning and they could not access the preferred food. Three dogs readily waited for the more-preferred treat. However, no dogs allowed one preferred treat to pass to pass to receive four or even eight of the same treat later. Therefore, dogs' self-control depended on the quality of the treat they wait for, but not quantity. Future studies could explore the relation between self-control and behavioral outcomes in dogs in an effort to provide insight into behavioral problems such as separation anxiety or destructive behaviors.

Anatomical effects of exercise following ischemic insult in young and aged c57BL/6 mice
by Mark Curtis

Stroke is a leading cause of long-term disability. Current rehabilitative strategies are expensive and often fail to yield complete recovery. Focused training of the impaired limb improves outcome in rodents, but these strategies require intensive training that is not feasible for humans. Because aerobic exercise has been found to induce beneficial changes in the brain, it is a promising rehabilitative strategy following stroke. Exercise may require less intensity and is less expensive than traditional therapy. Understanding the mechanisms underlying recovery from animal models will aid in optimizing rehabilitation strategies in human patients. Research using a mouse model of exercise rehabilitation after stroke allows for a better understanding of mechanisms of recovery through tissue analysis. The current study investigated the effect of post-stroke exercise on young and aged mice. Mice were trained on a skilled reaching task before receiving focal ischemic stroke. Mice were subdivided into three different groups for rehabilitative training: traditional rehabilitation, aerobic exercise, and control procedures. Both young and aged mice benefited from aerobic exercise after stroke. The improved motor function recovery was not associated with increased levels of neurogenesis in the peri-infarct cortex in either the young or aged mice. Aerobic exercise may be an affordable and effective alternative to traditional rehabilitative strategies, but these results suggest the total number of new neurons recruited to the region surrounding the lesion is not underlying its efficacy. Alternative potential mechanisms need to be further investigated.

Emotional and Social Responses to Stargazing: What Does It Mean To Lose the Dark?
by Analeigh Dao

Based on research documenting benefits of contact with nature on human well-being, and the harm of exposure to environmental degradation, this study explored the effects of stargazing on human psychological reactions. A laboratory-based experimental study was conducted to assess the emotional and social effects of stargazing on humans and how those effects differ when the view of the night sky is degraded rather than intact. All participants watched two slideshows, once of night sky scenes (to mimic stargazing) and one of geometric figures (a control task). Half of the participants were randomly assigned to watch intact versions of the slideshows (i.e., images of dark sky, colored figures) and half were assigned to watch degraded versions (i.e., light polluted sky, black-and-white figures). After each slideshow, participants completed questionnaires about their general emotions, awe experiences, and pro-social responses. Participants reported significantly less stress, more positive mood, and stronger awe experiences after viewing night sky scenes than after viewing geometric figures. In contrast, results for pro-social responses were more mixed. Contrary to hypotheses, the level of degradation had little effect on participants' responses. Results support previous research by affirming the benefits of contact with nature for psychosocial functioning and do so for a less studied yet potentially important human experience - stargazing.

Differences in Spatial Cognition in Captive Tigers and Bears
by Jessica Kraut

Migrating long distances to find food, mates, and territories requires animals navigate long distances, yet exactly what cognitive mechanisms support such navigation remains unclear. Non-mammalian spatial cognition research suggests animals have an integrated map consisting of bearing (egocentric mechanisms:e.g., dead reckoning) and sketch ( allocentric mechanisms: e.g., landmarks) maps. Do mammals that migrate, tigers and bears, also use these maps? Two Sumatran tigers (one female, one grizzly bear (female), and one polar bear (female) observed a rotating apparatus with two distinct landmarks, one baited with food. The animals chose which side had food using landmarks or rotation as cues. Binomial tests revealed animals found food more than expected by chance, and bears and the female tiger found food more than the male tiger. Thus, mammals can use a sketch map (landmarks or rotation) to find food. Further research should explore whether mammals rely on bearing maps and should further investigate species differences in sketch map use.