Joshua M. Ackerman’s research while affiliated with Concordia University Ann Arbor and other places

How does living in an environment with many or few family relatives shape our psychology? Here, we draw upon ideas from behavioral ecology to explore the psychological effects of ecological relatedness—the prevalence of family relatives in one’s environment. We present six studies, both correlational and experimental, that examine this. In general, people and populations that live in ecologies with more family relatives (Studies 1–4b), or who imagine themselves to be living in such ecologies (Studies 2/3a/3b/4b), engage in more extreme pro-group behavior (e.g., being willing to go to war for their country), hold more interdependent self-concepts, are more punishing of antisocial behaviors (e.g., support the death penalty for murder), identify themselves as more connected to and trust nearby groups (e.g., their community and neighbors) but less so distant groups (e.g., foreigners, the world), and also judge sibling incest as more morally wrong. These effects are examined across three countries (the United States, Ghana, the Philippines) and are robust to a range of controls and alternative explanations (e.g., ingroup preferences, familiarity effects, kinship intensity). The current work highlights the psychological effects of an underexamined dimension of our social ecology, provides a set of methods for studying it, and holds implications for understanding the ecological origins of a range of social behaviors and cultural differences.

In 2020, the growing COVID‐19 pandemic threatened engagement with the U.S. presidential election. Did this threat affect how people perceived the voting process and the means by which they voted? Four months before the election, 564 participants in several states viewed slideshows framing the pandemic primarily as a health or economic threat, then rated their impressions of voting environments and their attitudes about various voting methods. Following the general election, these data were matched to records indicating if and how participants voted. Exposure to the health consequences of COVID‐19 led people to judge socially dense polling places more negatively but had few effects on other voter outcomes. Instead, chronic aversion to germs predicted more negative responses to dense polling places as well as support for, and use of, socially distanced voting methods, even when accounting for other relevant factors such as partisanship and local COVID‐19 rates.

People sick with infectious illnesses face negative social outcomes, like exclusion, and may take steps to conceal their illnesses from others. In 10 studies of past, current, and projected illness, we examined the prevalence and predictors of infection concealment in adult samples of U.S. university students, health-care employees, and online crowdsourced workers (total N = 4,110). About 75% reported concealing illness in interpersonal interactions, possibly placing others in harm’s way. Concealment motives were largely social (e.g., wanting to attend events like parties) and achievement oriented (e.g., completing work objectives). Disease characteristics, including potential harm and illness immediacy, also influenced concealment decisions. People imagining harmful (vs. mild) infections concealed illness less frequently, whereas participants who were actually sick concealed frequently regardless of illness harm, suggesting state-specific biases underlying concealment decisions. Disease concealment appears to be a widely prevalent behavior by which concealers trade off risks to others in favor of their own goals, creating potentially important public-health consequences.

Vaccines can affect the mind as well as the body. Research on the psychological impact of vaccines has largely focused on risk‐related judgments and behaviors involving the recipient. Here, we extend this work to risk‐related judgments of others . In a prospective cohort study involving three samples and two timepoints ( N = 588 adults), we tested competing hypotheses about the effects of receiving a COVID‐19 vaccine on perceived risks to the unvaccinated: (1) a self/other differentiation hypothesis (vaccination will lead to estimation of lower risk for the self but higher risk for others) versus (2) a self/other correspondence hypothesis (vaccination will lead to estimation of lower risk from contracting COVID‐19 for both self and others). Results revealed risk estimates as well as preferences for COVID‐related social policies more consistent with the former hypothesis. We discuss potential psychological mechanisms and implications of these findings.

The coronavirus disease 2019 (COVID‐19) pandemic has had a vast, but uneven, influence on consumers. Diversity in consumer reactions, and the extent to which those reactions lead to lasting preference and lifestyle changes, present challenges for implementing effective marketing strategies during a period of societal crisis. To address this, we conducted a dynamic segmentation analysis involving over 14,000 U.S. women by assessing relevant psychological, experiential, and other personal factors at multiple time points during the pandemic. This analysis identified seven unique consumer segments who varied in their current and future degree of change, and who indicated responsiveness to specific forms of brand and advertising content. This seven‐segment clustering was highly stable over time, suggesting that certain segmentation approaches hold continuing value for marketers even as widespread events like pandemics evolve.

Individual differences exist in perceived vulnerability to disease (PVD). PVD is associated with negative responses (e.g., disgust) towards individuals with obesity and heightened sensitivity regarding personal appearance. Through increasing fear of fat (FOF), PVD may be associated with cognitive restraint and compensatory behaviors. We utilized an adult sample (n = 247; 53.3% male sex assigned at birth) recruited through Amazon’s MTurk prior to the COVID-19 pandemic to investigate associations between PVD, cognitive restraint and compensatory behaviors. Participants completed the Perceived Vulnerability to Disease Scale, Eating Disorder Diagnostic Scale, Dutch Eating Behaviors Questionnaire, and Goldfarb’s Fear of Fat Scale. Mediation analyses were used to test our hypotheses. Perceived infectability (PVD-Infection) was associated with cognitive restraint and compensatory behaviors through increased FOF. Perceived germ aversion (PVD–Germ) was associated with cognitive restraint, but FOF did not mediate this association. Sex-stratified analyses revealed no significant sex differences. PVD may be an overlooked factor associated with cognitive restraint and compensatory behaviors in males and females. FOF was an important mediating factor in these associations. Increased engagement in cognitive restraint and compensatory behaviors may reflect attempts to reduce FOF. Future longitudinal research should explore whether PVD is a risk factor for cognitive restraint and compensatory behaviors.

Pain is a critical internal regulator of current and future behavior. However, pain also constitutes a tactical liability in agonistic interpersonal conflict. Therefore, information about the pain sensitivity of others should play a functional role in assessments of the formidability of prospective foes or allies. Compared to an individual known to be sensitive to pain, an individual known to be insensitive to pain should be assessed as more formidable, as it would be more difficult to deter the latter from aggressing, and more difficult to motivate them to desist should conflict erupt. Further, knowing that a potential antagonist is armed should lead observers to infer relative insensitivity to pain, as the costs of erroneously presuming that an armed individual is sensitive to pain – and thus is both more vulnerable and less likely to aggress – will generally be higher than the costs of erroneously presuming that they are insensitive to pain, and thus are both less vulnerable and more inclined to aggress. Here, we find support for these predictions in three pre-registered studies conducted with U.S. online crowdsource workers (N = 473; N = 204; N = 301). The intimate association between information regarding pain sensitivity and the process of formidability assessment has implications for a variety of pressing social issues, from the use of excessive force by police, to discriminatory racial biases in the provision of medical care.

The current study examines predictors of social distancing behavior across populations (students and community members) and across time in the early months of the COVID-19 pandemic, focusing on two factors commonly associated with risk perception and prevention: knowledge and affect. Results showed that, despite similar levels of social distancing, student distancing was predicted only by feelings of threat about COVID-19, whereas community distancing was predicted by both feeling informed and threatened. Examining longitudinal effects, which were limited to students only, students became more informed about COVID-19 over time, and increases in being informed (but not feeling threatened) predicted more distancing.