Allies, friends, romantic partners, rivals, and other associates can have profound effects on our welfare (Aktipis et al., 2018; DeScioli and Kurzban, 2009; Dunbar, 2018; Schmitt and Buss, 2001; Silk et al., 2003). Friends bolster our ability to weather times of hardship (Tooby and Cosmides, 1996). Romantic partners help us produce and care for offspring (Charpentier et al., 2008; Hill and Hurtado, 1996). Rivals hinder our access to resources, including partners and status (Buss et al., 2000; Duntley and Buss, 2011; Hilbe et al., 2018). Correspondingly, people's attitudes toward others appear to match the probable effects that others will have on their welfare: People value and like those who have a stake in their welfare or that of their kin (Lewis et al., 2015; Smith-Flores et al., 2024; Sznycer et al., 2019); people disvalue and dislike competitors, rivals, and enemies (Adams, 2005; Holt, 1989; Wiseman and Duck, 1995).

But people's dyadic interactions with their associates—friends, spouses, rivals—do not take place in a social vacuum. Rather, they take place within densely-interconnected social networks (Basyouni and Parkinson, 2022; Feld, 1981). Therein, non-associates (e.g., strangers) can impact one's welfare. Welfare effects from strangers can stem from strangers' (a) interactions with oneself (e.g., X helps me), (b) interactions with one's associates (e.g., X courts my spouse), or (c) mere existence and activities (e.g., X pollutes the river) (see Krems et al., 2023; Sznycer, 2022; Tooby and Cosmides, 1996). Prospectively estimating the total welfare effects one incurs from an individual (via interactions with oneself, one's associates, the environment, etc.) is a precondition for one to adaptively value and behave with respect to that individual: to associate with them, help them, avoid them, harm them, and so on.

Stranger-associate interactions can have potentially profound effects on one's welfare—as when strangers usurp one's place in a friendship, poach one's mate, or defeat one's rival (Aronson and Cope, 1968; Krems et al., 2021a, Krems et al., 2022; Lukaszewski and Roney, 2010; Schmitt, 2004; Schmitt and Buss, 2001). Yet little is known about whether the mind computes expected welfare effects resulting from person X's interactions with one's associates,1 and, if so, how the mind uses these estimates to calibrate attitudes and behavior toward person X.

Here, we focus on such welfare effects from stranger-associate interactions: How does one feel toward those individuals who affect one's outcomes, not by interacting with oneself, but by affecting other people besides oneself? We begin to address this by focusing on how strangers impact one's welfare through interactions with one's associates—specifically, one's friend, romantic partner, or rival. We test whether one's attitudes toward strangers are shaped by cue-based indications of the probable effects that stranger-associate interactions will have on one's own welfare. For example, I might dislike a stranger (person X) who is interested in poaching my spouse because, if I lose my spouse to them, that will hinder my welfare (e.g., Buss, 1988). By contrast, I might like X if they harm my enemy, perhaps because X reduces my enemy's ability to harm me, and thus enhances my welfare.

Specifically, we (1) investigate how cues of X's feelings toward one's existing associates (friends, romantic partners, rivals) affect one's attitudes toward X—based on the likely welfare effects on oneself that might result from X's interactions with one's associates. We also (2) contrast predictions about these attitudes derived from (a) the Embedded Dyad Framework—a novel framework which foregrounds the interconnectedness of social networks and the substantive welfare effects resulting from the supra-dyadic social challenges and opportunities people must navigate in order to thrive2—with predictions derived from (b) an influential formalist theory in social psychology: Balance Theory (Heider, 1946, Heider, 1958; Newcomb, 1953). Finally, we (3) investigate the causal paths underlying the predicted effects per the Embedded Dyad Framework: what causes people to anticipate positive or negative welfare effects from stranger-associate interactions. As an initial test of predictions derived from this framework, we focus on one characteristic that varies across functionally distinct domains of welfare-enhancing relationships (i.e., friendships and romantic relationships) and one characteristic that varies within the domain of welfare-suppressing relationships (i.e., rivalries).

Although much is known about welfare effects resulting from stranger-ego interactions (Aktipis et al., 2018; Aron et al., 1997; Sprecher, 2021; Tittler et al., 1979; Weaver and Bosson, 2011)—for example, how people anticipate whether those interactions will be positive or negative, how anticipated (or demonstrated) positive or negative effects influence people's subsequent behavior—we know relatively little about welfare effects resulting from stranger-associate interactions (but see, e.g., Buss, 2013; Heider, 1946; Krems et al., 2023; Lukaszewski and Roney, 2010; Pietraszewski and German, 2013). Here we focus on the latter.

All else equal, strangers who negatively impact one's close relationship partners (friends, romantic partners) are a source of costs for oneself. For example, if my spouse's co-worker spreads negative gossip about my spouse at work, that could preclude my spouse from being promoted and earning more money, which could hinder my outcomes as well. Thus, one will dislike individuals who, for example, hate one's spouse, because such hatred might indicate intentions to negatively impact one's welfare-enhancing partners, which hinders one's own welfare.

By contrast, strangers who benefit one's close relationship partners pose a more complex problem. On one hand, strangers who positively impact one's partners can benefit oneself as a result (e.g., by giving one's spouse restaurant gift cards one dines out on). On the other hand, there may be significant limits to such benefits. For example, a person's courting my spouse and giving them resources could also undermine my own relationship with my spouse, hindering my outcomes (Buss, 1988; Schmitt, 2004; Schmitt and Buss, 2001). Thus, one may dislike individuals who, for example, love one's spouse, as such love might indicate intentions to replace oneself in the spouse's limited mating niche, and hinder one's welfare (Buss, 2002; Yong and Li, 2018).

One important determinant of whether one might derive welfare benefits when a stranger shares one's positive feelings toward one's existing associates is the (perceived) exclusivity of one's close relationships: the degree to which the relationship niche is seen as being limited to one partner at a time. To illustrate, people may view some of their friendships as more exclusive than others (e.g., a “best” friend versus a “close” friend), such that a more-exclusive friend's new friendship with someone else is deemed more threatening to oneself than a less-exclusive friend's new friendship (Krems et al., 2021a, Krems et al., 2022). Likewise, people generally consider romantic relationships to be more exclusive than friendships (Sprecher and Regan, 2002). Thus, a stranger who shares one's positive feelings toward one's more-exclusive relationship partner (e.g., a spouse) poses a greater threat to displace oneself—to poach one's partner; and so one might dislike such strangers, or at least like them less than one likes strangers who share one's positive feelings toward a less-exclusive relationship partner (e.g., a friend).

The above pertains to close relationship partners—but people also have sometimes-enduring relationships marked by antipathy or hostility, as with rivals or enemies (e.g., Adams, 2005). Concerning such antagonistic, welfare-suppressing relationships, strangers who negatively impact one's antagonists might be inferred to benefit oneself via their interactions with one's antagonists. Concretely, a stranger might benefit oneself by harming one's enemy. Therefore, one will like such individuals who, for example, hate one's enemy, because such hatred might indicate intentions to negatively impact one's welfare-hindering partners, which enhances one's welfare. An important moderator of how much one might like such a stranger, then, is the degree to which one perceives one's antagonist as suppressing one's own welfare (or the welfare of close associates). For example, all else equal, I might benefit more when a stranger harms an enemy seeking to end my life (strong welfare-suppressor) than when they harm my noisy neighbor (mild welfare-suppressor).

Classic theories emphasizing the importance of maintaining cognitive consistency (Abelson et al., 1968; Festinger, 1957; Insko, 1984; Jones and Davis, 1965; Osgood and Tannenbaum, 1955)—and most famously Balance Theory (Heider, 1946, Heider, 1958; Newcomb, 1953)—make some similar predictions to those outlined above. Indeed, unlike most theories of relationships and attraction (for a review, see Fehr, 1996),3 cognitive consistency theories consider extra-dyadic actors (or objects). Perhaps because of this, Balance Theory remains highly influential in social psychology more than half a century after its inception (e.g., Chiang et al., 2020; Crandall et al., 2007; Sarazin, 2021).

Balance Theory posits that the mind seeks cognitive consistency—including by pursuing balanced social relationships (as when I and my friend both dislike the same person). On this view, people prefer balanced triads to imbalanced triads, and imbalance—such as occurs when my friend dislikes my spouse, whom I love—creates unpleasant psychological tension in one's own mind. Balance Theory therefore proposes that individuals like other people when those other people's feelings toward a person or object match the individual's own (and dislike others who feel differently). This aspect of Balance Theory predicts people's attitudes toward objects and other people, including strangers. For example, if a stranger and I both like my friend, then I will like the stranger (because this attitude creates affective balance). However, if the stranger's feelings toward my partner, whether positive or negative, are inconsistent with my own, then I will dislike the stranger (because this attitude creates affective balance).

Balance Theory and the Embedded Dyad Framework introduced above (see also Krems et al., 2023) both predict that people generally (a) like strangers who share their positive feelings toward their close relationship partners (e.g., people like strangers who share their love for their friends), (b) like strangers who share their negative feelings toward their antagonists (e.g., people like strangers who share their dislike for their enemies), and (c) dislike strangers whose feelings toward these dyadic partners are opposite to their own (e.g., people dislike strangers who dislike their friends or like their enemies).

But there are important exceptions: Consider a stranger who expresses feelings of love and attraction toward my spouse—feelings matching my own feelings for my spouse. Whereas Balance Theory predicts that I would like that stranger (because liking a stranger who shares my love toward my spouse would result in a balanced triadic network), an embedded dyad view predicts that I would not.4 Indeed, this is a primary point of divergence between predictions derived from Balance Theory and the Embedded Dyad Framework.