Original Article
Stranger danger: Parenthood increases the envisioned bodily formidability of menacing men

https://doi.org/10.1016/j.evolhumbehav.2013.11.004Get rights and content

Abstract

Due to altriciality and the importance of embodied capital, children's fitness is contingent on parental investment. Injury suffered by a parent therefore degrades the parent's fitness both by constraining reproduction and by diminishing the fitness of existing offspring. Due to the latter added cost, compared to non-parents, parents should be more cautious in hazardous situations, including potentially agonistic interactions. Prior research indicates that relative formidability is conceptualized in terms of size and strength. As erroneous under-estimation of a foe's formidability heightens the risk of injury, parents should therefore conceptualize a potential antagonist as larger, stronger, and of more sinister intent than should non-parents; secondarily, the presence of one's vulnerable children should exacerbate this pattern. We tested these predictions in the U.S. using reactions to an evocative vignette, administered via the Internet (Study 1), and in-person assessments of the facial photograph of a purported criminal, collected on the streets of Southern California (Study 2). As predicted, parents envisioned a potential antagonist to be more formidable than did non-parents. Significant differences between parents with children and non-parents without children in the threat that the foe was thought to pose (Study 1) were fully mediated by increases in estimated physical formidability.

Introduction

Humans are unique among primates in both the altriciality of our offspring and the degree to which learning and other forms of embodied capital can affect offspring fitness (Kaplan, Lancaster, & Robson, 2003). This combination creates the potential for a high rate of return on parental investment. We can therefore expect natural selection to have favored the evolution of multiple psychological adaptations regulating a variety of behaviors related to parenting. To date, considerable work has explored factors bearing directly on parental investment, including, for example, mechanisms active in attraction to infants (Glocker et al., 2009, Parsons et al., 2011), parent–infant bonding (Bowlby, 1982, Carter, 2005, Feldman et al., 2010), and discriminative parental solicitude (Daly & Wilson, 1995). More recently, investigators have begun to explore the consequences of parenthood for social relations with third parties, a notable example being the effects of lactation on maternal aggression toward transgressing adults (Hahn-Holbrook et al., 2011a, Hahn-Holbrook et al., 2011b). Such work dovetails with studies in animal behavioral ecology that explore responses to the risk of infanticide (van Schaik & Janson, 2000). Importantly, logic suggests that the consequences of parenthood for relations with potentially dangerous third parties extend beyond the period when offspring are infants, and, indeed, beyond situations in which offspring are in harm's way. Specifically, the potential for substantially enhancing the success of one's children through continued investment over a period of many years means that parental injury degrades a parent's fitness not merely by limiting or truncating the parent's reproduction, but also by reducing the fitness of existing offspring (Hurtado and Hill, 1992, Scelza, 2010). Correspondingly, for individuals pursuing a reproductive strategy involving substantial parental investment, parenthood should notably influence social cognition with regard to potentially agonistic situations.

The impact of parenthood on social cognition in potentially agonistic contexts can be decomposed into at least three separable but interrelated components. First, given the consequences of parental injury for offspring fitness, we can expect parenthood to be accompanied by a decrease in the propensity to take risks with one's health and welfare: when the probabilities of both positive and negative outcomes are known, relative to non-parents, parents should display a reduced preference for options that, though potentially yielding large rewards, are also accompanied by a risk of injury (Campbell, 1999, Wang et al., 2009, Hahn-Holbrook et al., 2011a, Hahn-Holbrook et al., 2011b). As a consequence, in general, when facing an antagonist, parents should be less inclined to engage in combat than non-parents. One important exception to this generalization concerns situations in which the antagonist threatens the parent's child, in which case, by virtue of their vested interest in the child's welfare, parents can be expected to be more inclined than non-parents to engage in combat (Maestripieri, 1992). Second, when others' intentions are unclear, parents should display more conservative error management strategies (Galperin & Haselton, 2012) in estimating said intentions. The threshold for presuming that another harbors hostile intent should thus be lower in parents than in non-parents, as this will reduce the likelihood that the perceiver will fail to identify an assailant—in short, parents should assess potential assailants as more malevolent in ambiguous situations, since failing to identify an attack is more costly than is falsely suspecting attack in a benign context. With the exception of the reversal of parents' aversion to combat in parental defensive aggression when attack is imminent (Hahn-Holbrook et al., 2011a, Hahn-Holbrook et al., 2011b), the presence of one's child should intensify parental misgivings about others' intentions in ambiguous situations, as the child's vulnerability increases the value of a pessimistic estimation in this regard. Third, when faced with an apparently agonistic context, in deciding whether to fight, attempt to negotiate, or flee, parents should be more pessimistic than non-parents in estimating the fighting capacity, or formidability, of an antagonist relative to themselves, as this will reduce the likelihood that the parent will suffer injury due to inaccurate predictions of possible outcomes. In this case, too, the presence of one's child should intensify the pattern of pessimism. Here, after reviewing existing evidence in support of parental combat avoidance, risk-aversion, and distrust, we present results from two studies concerning the influence of parenthood on the estimation of relative formidability, a hitherto unexplored topic.

Parental avoidance of combat is a subsidiary category of a predicted general propensity for high-investing parents to be more averse than non-parents to situations involving a risk of injury (i.e., physical risk). One indirect index consonant with the predicted pattern is the finding that, across anthropoid primates, sex differences in survival rates reflect the degree and direction of sex differences in parental care (Allman, Rosin, Kumar, & Hasenstaub, 1998). However, survival rates are admittedly determined by many factors; to date, surprisingly little research addresses the question of whether parents are less likely to engage in physical risk-taking in general, and violence in particular, than non-parents. Beginning with the animal literature, studies of mice (Parmigiani, Palanza, Rodgers, & Ferrari, 1999) and howler monkeys (Cancelliere, 2012) reveal increases in precautionary behavior – presumably corresponding with increased aversion to physical risk – in females with dependent offspring. In humans, given the links between testosterone and aggression and related forms of risk-taking (reviewed in Yildirim & Derksen, 2012), it is suggestive that paternal testosterone declines following the birth of a child (Gray and Campbell, 2009, Gettler et al., 2011); cross-sectional evidence suggests that similar patterns occur in women as well (Kuzawa, Gettler, Huang, & McDade, 2010). However, the applicability of these observations is limited in that the principal proximate determinant of aggressiveness may be the plasticity of testosterone levels rather than baseline testosterone levels (Carré, McCormick, & Hariri, 2011). Baseline testosterone is associated with financial risk-taking (Stanton, Liening, & Schultheiss, 2011), and, for both sexes, parents have a lower tolerance for financial risk than non-parents (Chaulk, Johnson, & Bulcroft, 2003). Relatedly, among non-parents, women, but not men, show greater risk-aversion in a gambling task when a baby will share the proceeds compared to when the recipient is an adult (Fischer & Hills, 2012). However, the relevance of these findings is unclear given that financial risk-taking may be a poor predictor of participation in activities entailing a risk of injury (Blais & Weber, 2006).

Criminal offending frequently entails the possibility of violence and injury. For both men and women, high-investing parenthood is associated with reduced offending (Ganem & Agnew, 2007), particularly for individuals of higher socioeconomic status (Giordano, Seffrin, Manning, & Longmore, 2011). In regard to social conflict in more everyday settings, compared to non-parents, parents report lesser likelihood of engaging in risky behaviors in two domains, within-group competition and between-group competition, both of which entail the possibility of violence (Wang et al., 2009). A small interview study finds reduced self-reported male physical risk-taking following the birth of a child (Garfield, Isacco, & Bartlo, 2010), although the qualitative nature of the results limits their robustness. More broadly, a large economic survey documents that parents are more willing than non-parents to pay for programs that reduce the risk that they will suffer serious health problems (Cameron, DeShazo, & Johnson, 2010).

In a series of papers, Eibach and colleagues explore the relationship between parenthood, perceptions of danger, and related considerations such as distrust. Correlating reported perceptions of increases in danger in society with the year in which participants' children were born, Eibach, Libby, and Gilovich (2003) find that parenthood appears to make the world seem more dangerous (similarly, Drottz-Sjöberg & Sjoberg, 1990 find that parents perceive nuclear energy to be more dangerous than do non-parents). Subsequent studies indicate that reminding individuals of their status as parents (by placing a demographic question concerning parenthood prior to dependent measures) enhances parents' perceptions of the dangerousness of a variety of features of the world, including the dangerousness of extreme sports, and the risk of criminal victimization (Eibach and Mock, 2011, Eibach et al., 2012). Somewhat surprisingly, one of these studies found no difference in perceptions of danger between parents and non-parents when parents were not reminded of their parenthood (Eibach & Mock, 2011). Consonant with the above patterns, Eibach and Mock (2011) also found that, when (and only when) their status as parents was primed, parents reported greater distrust of strangers than non-parents, and made less trusting (and less risky) decisions in hypothetical economic games.

Lastly, turning to parents' concerns for the welfare of their children rather than themselves, obsessive and intrusive postpartum ideation concerning potential hazards to infants occurs in both mothers and fathers, albeit more so in the former (Abramowitz, Schwartz, & Moore, 2003). More broadly, when compared with parental concerns regarding other hazards present in the contemporary environment, fear that one's children will be harmed by strangers looms disproportionately large in light of the actual risks that such individuals pose, a distortion explicable in terms of the operation of psychological mechanisms that evolved in a world in which conspecifics were a prominent threat (Hahn-Holbrook, Holbrook, & Bering, 2010).

To summarize the above, although the literature is surprisingly sparse given both the theoretical and the practical importance of the topic, nevertheless, there is some evidence that, compared to non-parents, parents are more likely to avoid risk-taking in general, physical risk-taking in particular, and violence as a specific case. The small subset of studies among these that tap issues of parental distrust of other's intentions is similarly consonant with theoretical expectations that parents should be more pessimistic in this regard than non-parents. Against this backdrop, we turn to the background for our novel prediction, that parents will be more pessimistic than non-parents in estimating the formidability of a potential assailant.

Formidability is always relative to a given agonistic context, as the outcome of a violent conflict hinges not on one's absolute fighting capacity, but on one's fighting capacity relative to that of one's foe. A wide variety of factors contributes to relative formidability, including strength, body size, sex, health, the possession of weapons, combat expertise, and the size and cohesiveness of coalitions. Such variety poses a challenge. In situations of potential violent conflict, individuals must rapidly decide whether to fight, flee, appease, or negotiate—the actor faces the problem of needing to consider multiple diverse attributes of the foe and of the self and quickly arrive at a decision as to how to act. When manifold factors contribute to a decision, it is often useful to compile the relevant information into a single representation. An emerging corpus of work indicates that, consonant with the phylogenetic antiquity and ontogenetic ubiquity of size and strength as important variables in this regard, the diverse determinants of relative formidability are summarized in a representation that employs the dimensions of size and strength: in essence, the greater the foe's formidability relative to one's own, the larger and stronger the foe is conceptualized as being. It is important to emphasize here that the aforementioned thesis refers to issues of representation, not to issues of perception. Size and strength are features of a mind’s-eye image that summarizes a wide variety of tactical assets and liabilities possessed by the prospective combatants—the mind represents potential foes as large and muscular when the foe possesses notable tactical advantages over oneself, and as small and non-muscular when the opposite obtains. There is thus no suggestion that actual perceptual processes (or, at the least, ‘perception-for-action’ processes [Milner & Goodale, 2008]) will be influenced by tactical attributes of either party—indeed, it would likely be maladaptive were this to occur, as, at a minimum, it would lead to a reduction in the effectiveness of offensive or defensive tactics (e.g., missed blows stemming from inaccurate perceptions of the opponent's height, etc.).

Consistent with the above hypothesis, knowing that a man possesses a gun or a knife increases estimations of his size and muscularity (Fessler, Holbrook, & Snyder, 2012); conversely, the presence of allies who could assist in a fight diminishes such estimations (Fessler & Holbrook, 2013a). Likewise, learning that the leader of a terrorist group has suffered military defeats, or, alternately, experienced successes, leads participants to respectively decrease or increase their estimations of the size and strength of a representative terrorist (Holbrook & Fessler, 2013). Being temporarily physically incapacitated leads men to perceive an antagonist as larger and stronger, and themselves as smaller (Fessler & Holbrook, 2013b), while a man's own strength is inversely correlated with his estimations of an antagonist's physical formidability (Fessler et al., in press [a]). Knowing that an individual is relatively indifferent to the possibility of injury or death – and thus is unlikely to back down in a conflict – increases estimations of his size and strength (Fessler et al., in press [b]). Racist stereotypes portraying outgroup members as dangerous are accompanied – and mediated – by conceptualizations of increased size and muscularity (Holbrook et al., n.d.). More broadly, being made to feel powerful leads participants to underestimate a target individual's size (Duguid and Goncalo, 2012, Yap et al., 2013) and overestimate their own (Duguid & Goncalo, 2012).

The above findings concerning the representation of relative formidability provide an avenue for exploring parental pessimism in formidability assessment, as asking parents and non-parents to provide estimates of another individual's size and muscularity constitutes an unobtrusive means of measuring predicted differences in the degree to which they are pessimistic in evaluating the formidability of a potential assailant. We therefore conducted two studies in the U.S., the first online and the second in person, in which we asked participants to estimate the height, body size, and muscularity of a target individual presented as a likely foe. If parental pessimism occurs, then parents should envision the stranger as larger and more muscular than should non-parents.

In Study 1, we asked participants to read an evocative vignette (adapted from Petralia & Gallup, 2002; see ESM, available on the journal's website at www.ehbonline.org) wherein the reader imagines him- or herself alone in a dark parking lot, having been followed – and ultimately approached – by an unfamiliar man; participants are then asked to estimate the antagonist's bodily characteristics. This design also affords an auxiliary exploration of parental distrust, as we can ask participants to judge the man's intentions and the corresponding danger that he poses, then explore the relationship between these judgments and perceptions of the man's relative formidability.

To investigate the predicted exacerbating effect of the presence of one's child on both parental pessimism in formidability assessment and parental distrust, in a separate condition, we modify the vignette, asking parents to envision themselves accompanied by their child (see ESM, available on the journal's website at www.ehbonline.org). However, should we observe that these parents respond differently than the parents who envisioned themselves alone, this observation by itself would not allow us to determine whether this effect is unique to the parent–child dyad. It is likely that, in the contemporary United States, most people believe that adults have a responsibility to protect children. As a consequence, while kin selection considerations predict an enhanced effect of the presence of one's own child compared to the effect of the presence of an unrelated child, nevertheless, the presence of any child may lead to increased caution in detecting potentially hostile agents and assessing their relative formidability. To tease apart these respective contributions, we add a condition in which parents are asked to envision themselves accompanied by an unrelated child (see ESM, available on the journal's website at www.ehbonline.org). Lastly, because the same broad moral considerations apply to non-parents, we add a condition in which non-parents are asked to envision themselves accompanied by an unrelated child (see ESM, available on the journal's website at www.ehbonline.org).

Section snippets

Participants

Via the nationwide market research firm uSamp (Encino, CA), 650 adult residents of the U.S. were recruited to participate in an online study described as a “survey of social intuitions” in exchange for $1. To be eligible, prospective participants had to be married (thus ensuring comparability between parents and non-parents with regard to relationship status), between the ages of 26 and 35 (a common age range for parents of young children), and, for those who were parents, have at least one

Preliminary analyses

Preliminary ANOVAs were conducted to test for demographic differences between parents and non-parents in income, politics, education, and age. Parents and non-parents significantly differed in political orientation (parents: M = 4.20; SD = 1.76; non-parents: M = 3.88; SD = 1.77; p = .05), and age in years (parents: M = 31.7; SD = 2.26; non-parents: M = 31.0; SD = 2.16; p < .001). Parents and non-parents also differed in education level; on average, parents had partially completed the requirements for an

Study 1 discussion

The results of Study 1 reveal that, as predicted, parents conceptualize a hypothetical potential antagonist as larger and more muscular than do non-parents, a pattern consistent with greater pessimism among the former regarding the relative formidability of the foe. In contrast to the stark effects of parenthood status, the effects of child presence do not reach statistical significance. Nevertheless, there are hints that, consistent with the tactical liability posed by the presence of a child

Participants

117 adult women who were either alone or in the presence of one or more children were recruited on public streets in exchange for $3 compensation. Six participants who did not complete the study were dropped, leaving a final sample of 111 women, with a mean age of 32.3 years (SD = 7.87). This sample consisted of 61 mothers (14 of whom were alone, and 47 of whom were accompanied by children) and 50 non-mothers (43 of whom were alone, and 7 of whom were with children). In the subsample of women

Preliminary analyses

Preliminary ANOVAs were conducted to test for demographic differences between mothers and non-mothers in income, politics, education, age, and relationship status. There were no significant differences in politics (p = .10) or education (p = .83). On average, mothers were older (M = 34.9; SD = 7.94) than non-mothers (M = 29.1; SD = 6.56), F(1, 109) = 16.98, p < .001, η2 = .14. Mothers also reported being in significantly more committed relationships (M = 3.62; SD = .87; median = “married or engaged”) than non-mothers (

Study 2 discussion

Study 2 replicated the core finding of Study 1: parenthood again exercised an independent influence on the envisioned formidability of a prospective antagonist, as mothers envisioned the angry male target as larger and more muscular than did non-mothers. The absence of differences in either self-assessed fighting ability or handgrip strength between mothers and non-mothers suggests that the aforementioned pattern is unlikely to be due to differences in actual formidability between the two

General discussion

Across two studies, we find support for our core prediction that being a parent is associated with more pessimistic assessments of the relative formidability of a prospective foe—parents consistently estimated the potential assailant to be more physically formidable than did non-parents, a pattern that, when operationalized in actual agonistic contexts, would reduce the likelihood that a parent would suffer injury due to underestimation of a foe's fighting capacity. Importantly, this appears to

Supplementary Materials

Supplementary data to this article can be found online at http://dx.doi.org/10.1016/j.evolhumbehav.2013.11.004.

Acknowledgments

This work was supported by the U.S. Air Force Office of Scientific Research under Award #FA9550-10-1-0511. We thank Stormy Needham, Anndi Daniello, Kelly Burley, Lilit Ter-astvatsatryan, Jiwon Nam, and Katie Swinnerton for research assistance.

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    The complete datasets for all studies reported in this paper are included in the Electronic Supplementary Material, available at www.ehbonline.org.

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