Date of Award


Document Type


Degree Name

Doctor of Psychology (PsyD)



First Advisor

William Meil, Ph.D.

Second Advisor

Laurie Roehrich, Ph.D.

Third Advisor

Krys Kaniasty, Ph.D.


Both locus of control (LOC) and sensation-seeking (SS) have been tied to substance abuse, but the relationship between these factors is unclear. Traditionally, LOC has been treated as a dichotomous variable, consisting of an internal and an external LOC control group; failing to recognize a middle group (bilocals) that appears to balance external and internal LOC beliefs. The current study examined the relationship(s) between LOC, SS, and substance use in undergraduates. Measures utilized in the study included Rotter's IE Locus of Control Scale (1966), Zuckerman's Sensation-Seeking Scale - Form IV (1996), a frequency of use chart modified from the Monitoring the Future (MTF) Scale (Johnston, O'Malley, Bachman, & Schulenberg, 2008), the Michigan Alcoholism Screening Test, and the Fägerstrom Test for Nicotine Dependence. The study was conducted via a web-based survey. Two hundred and six undergraduate students agreed to participate in the study; however, only 169 produced completed surveys. Participants were equally matched for gender, but the majority of participants were White Non-Hispanic, first year students between 18-20 years of age. A positive correlation between SS and substance use was found (r= -.28, p=.00). In contrast to previous research, evidence of LOC's unique predictive power on substance above and beyond the predictive power of SS and gender was also found. Additionally, an interaction effect was found between LOC and SS, such that SS group membership moderated the relationship between LOC group membership and substance use. Partial support for the existence of a trichotomous LOC group classification system and a potential protective factor the bilocal LOC group within the SS group was found. No significant main effect for LOC control or gender group differences was found. No significant interaction effects for gender groups in terms of substance use levels. LOC and SS were examined in relation to alcohol use and nicotine use. Group differences in alcohol and nicotine usage were not attributable to LOC group differences. Limitations of the current study are discussed, as are avenues for future research.