Human behavior, such as wearing a mask in public, affects the trajectory of the COVID-19 pandemic. A nationally representative survey of 1198 U.S. residents was used to study demographics, perceptions, and stated beliefs of residents who indicated they believe masks have a role in society in response to COVID-19 but self-reported not wearing masks in at least one public place studied. Individuals who believed wearing masks protected others were more likely to report voluntarily wearing them, providing possible evidence of altruism. Perceiving social pressure negatively impacted the probability of voluntary mask wearing amongst those who believed masks have a role in society, suggesting social shaming may not increase compliance among these individuals. Free-riding is one possible explanation for why an individual respondent may self-report belief that mask wearing has a role in society and simultaneously self-report not voluntarily wearing a mask in public locations. Alternatively, incomplete knowledge, confusion about the role of masks in controlling spread of COVID-19, or fatigue are all possible explanations for why adults who believe masks play a role demonstrate less than optimal compliance themselves with mask wearing. Promotion of altruism, rather than social shaming, is more likely to increase mask wearing based on this analysis. Tactics to improve public health initiative compliance and participation may change throughout the duration of the pandemic and/or may differ between segments of the population. Increased understanding of human behavior as it relates to mask wearing can inform public health communications and construction of incentive-aligned messaging to improve public health-related behaviors and associated outcomes.