PhD Oral Exam - James Borenstein-Laurie, Psychology

When studying for a doctoral degree (PhD), candidates submit a thesis that provides a critical review of the current state of knowledge of the thesis subject as well as the student’s own contributions to the subject. The distinguishing criterion of doctoral graduate research is a significant and original contribution to knowledge.

Once accepted, the candidate presents the thesis orally. This oral exam is open to the public.

Abstract

Across decades of research, people with more positive expectations for the future (i.e., dispositional optimism) have been shown to enjoy better physical health (Rasmussen et al., 2009) and subjective well-being (Scheier et al., 2001). Theories of self-regulation suggest that these benefits stem from the role of dispositional optimism in motivating adaptive responses to stressors encountered in the pursuit of valued goals (Wrosch et al., 2025). Indeed, reduced psychological distress and better regulation of stress-related physiological systems may underlie associations between dispositional optimism and downstream health (Scheier & Carver, 2018). Despite this extensive work, several important questions remain.

Although dispositional optimism is typically conceptualized as a single bipolar construct, recent meta-analytic work supports distinct and stronger health effects of pessimism than optimism (Scheier et al., 2021). Most research has emphasized between-person differences in dispositional optimism, ignoring the impacts of within-person variability in optimism and pessimism for physical health over time (e.g., Voelkle et al., 2014). Furthermore, the roles of subjective well-being and health biomarkers in mediating or moderating these associations remain unclear. The present dissertation addresses these gaps.

Study 1 investigated within- and between-person health effects of optimism and pessimism in two samples experiencing non-normative (caregivers; n = 126) and normative stress (community-dwelling older adults; n = 160). Indicators of subjective well-being (i.e., depressive symptoms, general and caregiving-specific stress) were tested as mediators and moderators in these associations. Across samples, higher-than-average and higher baseline levels of pessimism (but not optimism) predicted worse physical health. Poorer subjective well-being mediated several pessimism–health associations, while moderation findings were inconsistent.

Study 2 evaluated the role of low-grade inflammation, indexed by interleukin-6 (IL-6), in pessimism­–health associations among 198 community-dwelling older adults. Higher-than-average pessimism (but not optimism) again predicted worse physical health, while baseline optimism and pessimism were unrelated to average physical health across study waves. Against expectations, IL-6 did not mediate or moderate pessimism–health associations. Exploratory analyses extended prior work that documented few links between optimism, pessimism, and health biomarkers (Arbel et al., 2020).

This dissertation contributes to theory in personality and health psychology, with implications discussed for future research and clinical practice.