Theses and Dissertations

Exploration of a mouse model (C57BL/6J) capable of demonstrating behavioral changes after adolescent social isolation that are consistent with prior findings may prove beneficial in later research. This study examined 2 proposed long-term effects of isolated housing (one mouse/cage), when compared to group housing (two mice/cage) during adolescence. Mice were placed in their respective housing conditions after weaning (PND 21) and remained in those conditions until PND 60. The same cohorts were used in both phases of the experiment. Phase 1 sought to confirm previous findings that showed increases in ethanol intake after adolescent social isolation using a 2-bottle preference Drinking-in-the-Dark (DID) design over a 4-day period (PND 64-PND 67.). Phase 2 sought to elucidate the effects present after adolescent social isolation, as measured using response inhibition capabilities demonstrated during fixed-minimum interval (FMI) trials (PND 81-PND 111). Findings in phase 1 of the experiment were non-significant, save a strong tendency for female mice in both housing conditions to drink more as a proportion of their bodyweight (g/kg). However, a trend of lower bodyweight in single housed mice did exist, which does suggest that detrimental stress was applied via the used of adolescent isolation in that housing condition. Findings in phase 2 showed little effect of adolescent social isolation on mean inter-response time (IRT) at any criterion used (FMI-0, FMI-4, FMI-6). Evaluation of mean interquartile range (IQR) of IRTs showed a significantly greater amount of variation in IRT responses within single housed mice at the highest criterion (FMI-6), and a trend in the same direction when FMI-4 and FMI-6 were tested concurrently. Taken as a whole, the findings of this experiment suggest that the effect of adolescent social isolation on ethanol intake is far less robust than the effect of sex and may be difficult to replicate in a low-power study. Additionally, adolescent social isolation may interfere with the ability of mice to show consistent accuracy during FMI tasks or a delay in recognition of FMI criterion change.

Recent studies indicate that words containing /ӕ/ and /u/ vowel phonemes can be mapped onto the emotional dimension of arousal. Specifically, the wham-womb effect describes the inclination to associate words with /ӕ/ vowel-sounds (as in “wham”) with high-arousal emotions and words with /u/ vowel-sounds (as in “womb”) with low-arousal emotions. The objective of this study was to replicate the wham-womb effect using nonsense pseudowords and to test if findings extend with use of a novel methodology that includes verbal auditory and visual pictorial stimuli, which can eventually be used to test young children. We collected data from 99 undergraduate participants through an online survey. Participants heard pre-recorded pairs of monosyllabic pseudowords containing /ӕ/ or /u/ vowel phonemes and then matched individual pseudowords to illustrations portraying high or low arousal emotions. Two t-tests were conducted to analyze the size of the wham-womb effect across pseudowords and across participants, specifically the likelihood that /ӕ/ sounds are paired with high arousal images and /u/ sounds with low arousal images. Our findings robustly confirmed the wham-womb effect. Participants paired /ӕ/ words with high arousal emotion pictures and /u/ words with low arousal ones at a 73.2% rate with a large effect size. The wham-womb effect supports the idea that verbal acoustic signals tend to be tied to embodied facial musculature that is related to human emotions, which supports the adaptive value of sound symbolism in language evolution and development.

As the use of social media becomes more prevalent, especially in adolescents and young adults, there is a growing need to understand how social media use affects psychological well-being in the emerging adult population. Prior research has found that exposure to nature reduces stress and increases attention in comparison to urban environments, but nature has not been studied as a way to reduce the potentially negative effects of social media. The current study aimed to determine if viewing social media or nature for a brief time affected psychological well-being, social comparisons, future self-identification, and awe, and to test whether viewing nature scenes could buffer the effects of viewing social media. Data was collected from 275 participants using a survey on Amazon Mechanical Turk. Results showed that emerging adults exposed to nature scenes had significantly less negative affect compared to those exposed to their social media feeds. Exploratory analyses showed that those who spent more time outside tended to experience decreased negative affect when they viewed both social media and nature photos, but those who spent more time outside experienced increased negative affect when only viewing social media. Those who used social media more often generally experienced lower negative affect. Findings show that relations between humans, social media, and nature, are complex, and further research into these relations and their underlying causes may be beneficial.

ADHD is a neurodevelopmental disorder associated with a high rate of comorbidity with anxiety disorders (25-34%). Children with ADHD experience serious adverse outcomes secondary to impairment in executive function, particularly within the domain of working memory (WM), behavioral inhibition (BI), and sustained attention (SA). While executive function deficits in ADHD are well documented, whether and how comorbid anxiety affects cognitive performance are equivocal. One potential explanation is that most studies examine linear relations, yet evidence suggests that anxiety affects performance in a non-linear (quadratic) manner, consistent with the the Yerkes-Dodson Law. The aim of this study was to investigate whether 1) children with ADHD show deficits in WM, BI, and SA relative to typically developing children, 2) comorbid anxiety displays a linear or nonlinear relationship with WM, BI, and SA performance among children with ADHD and 3) between group differences in cognitive performance vary based on levels of anxiety. Linear and non-linear relations between anxiety and cognitive performance were assessed in a sample of 54 boys diagnosed with ADHD and 50 typically developing boys. Anxiety was assessed across dimensions and raters. Results indicate rater and domain-specific effects of comorbid anxiety on cognitive performance. Non-linear relations between children’s self-rated physiological anxiety and Phonological working memory (PHWM), Visuospatial working memory (VSWM), and the Central Executive (CE) were found. Non-linear relations between parent-rated anxiety and PHWM and the CE were also found. However, no significant linear or non-linear effects of anxiety on BI and SA were found. The results indicate that children with moderate self-rated and parent-rated anxiety performed better on WM measures relative to those with low and high levels of self-rated and parent-rated anxiety. The present study was the first to examine and document non-linear effects of anxiety on cognitive performance among children diagnosed with ADHD. Given the results, clinicians should continue to assess anxiety during diagnostic screening in ADHD samples. Treatments should focus on compensating for CE abilities and mitigating high levels of anxiety as it may further impair WM.