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.
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.
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.
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.
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.
Stroke is the leading cause of long-term disability in the United States, making research on rehabilitation imperative. Stroke rehabilitation typically focuses on recovery of the bad limb, although this process is tedious. Compensatory use of the good limb after stroke is more efficient, but it is known to negatively impact the bad limb. Exercise may help with this problem; research has shown that exercise promotes neuronal growth and prevents cell death. This study used mice to investigate whether exercise after stroke could prevent deterioration of the bad limb despite compensatory training of the good limb. Results showed that mice that exercised, with or without good limb training, retained bad limb functionality. Mice that did not exercise did not retain bad limb abilities and displayed poor recovery of the bad limb with delayed rehabilitative training. These findings suggest that exercise can prevent the deterioration of bad limb function that is typically seen with good limb use.
Neural and Behavioral Effects of Social Exclusion on Self-Regulatory Control
by Anna C. Moczynski
Research indicates that social exclusion has negative effects across behavioral and emotional domains. Recent studies found that exclusionary events diminish levels of neural activity and task accuracy, suggesting that processes used for self-regulation during social events and cognitive tasks share a neural framework. The current study implements a time-estimation task as the cognitive performance outcome measure, providing insights on how social exclusion affects self-regulation during a cognitive task with ongoing feedback. Recognizing the anterior cingulate cortex (ACC) as being involved in self regulation, this study examines two indices of ACC activation --- the feedback related negativity (FRN) and the N2 --- following a social event created by the Cyberball paradigm. Results revealed that social exclusion affected behavioral activity such that task accuracy and reaction times did not improve on the second cognitive task for excluded participants whereas these performance variables did improve for included participants. We found a negative relationship between neural behavior during the social task and neural behavior on the subsequent cognitive task. These findings provide evidence for social exclusion's disruptive effect on self-regulatory resources.
Stress & Well-being: The Role of Relationship Quality with Adult Children
by Niccole A. Nelson
The current study explores how aspects of social support exchanged between older parents and their adult children might arbitrate the effects of stress on positive and negative affect. While unchecked stress can be deleterious to well-being, social support is frequently considered advantageous to well-being. As such, scores of studies have described social supports' modulating role in the relationship between stress and well-being; however, support for this role has been inconsistent. Although the literature suggests family support increases in importance as people age, and that the quality of relationships with adult children in particular have notable social and psychological consequences for older parents, relationship quality between older parents and adult children does not appear to have been well-explored in the context of the relationship between stress and well-being. The following paper describes the creation of a measure of relationship quality with adult children, and focuses on how this aspect of social support arbitrates the relationship between stress and well-being. In particular, date from Successful Aging in Context, an ongoing, longitudinal study of adult aging and development, were used to test whether relationship quality with adult children mediates the relationship between stress and affect (both positive and negative); for completion, follow-up analyses investigated moderating relationships among these variables. Results suggest that relationship quality with adult children positively relates to positive affect, but negatively relates to negative affect and perceived stress. These results lend support to the direct effect hypothesis regarding the relationship among social support and well-being; thus, high-quality relationships with adult children have salubrious effects on well-being with or without stress.
Neural and Behavioral Effects of Social Exclusion on Self-Regulation
by Natalie R. Weimer
Researchers investigating the effects of social exclusion on neural activity propose there is a common neural framework underlying self-regulatory processes for both social and cognitive behaviors. This study will shed light on the engagement of these processes across social and cognitive task domains by investigating the effects of social exclusion on cognitive task execution. Neural and behavioral activity were measured while participants completed two flanker task sessions with the Cyberball paradigm occurring in between; additionally, half of the participants experiences exclusion during the Cyberball paradigm. Results showed that, similar to previous research, social exclusion led to impairments in subsequent flanker task performance. Further, there was a relationship between neural activity and task behavior. For excluded participants, neural activity during the first flanker task session was associated with neural activity during Cyberball. These findings diverge from previous studies by suggesting that social exclusion via Cyberball doesn't just impair post-error performance in subsequent task; rather exclusion impacted overall task performance in the current study.