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Abstract Reciprocity and pseudo‐reciprocity are two important models for the evolution of cooperation and often considered alternative hypotheses. Reciprocity is typically defined as a scenario where help givencauseshelp received: cooperation is stabilized because each actor's cooperative investments are conditional on the cooperative returns from the receiver. Pseudo‐reciprocity is a scenario where helpenablesbyproduct returns: cooperation is inherently stable because the actor's cooperative investments yield byproduct returns from the receiver's self‐serving behavior. These models are strict alternatives only if reciprocity is defined by the restrictive assumption of zerofitness interdependence, meaning that the helper has no “stake” in the receiver's fitness. Reciprocity and interdependence are, however, not mutually exclusive when helping can increase both reciprocal help and byproduct returns. For instance, helping partners survive can simultaneously increase their willingness to reciprocate, their ability to reciprocate, and byproduct benefits of their existence. Interdependence can “pave the road” to reciprocal helping, and partners who reciprocate help can also become interdependent. However, larger cooperative investments can increase the need for responsiveness to partner returns. Therefore, most long‐term cooperative relationships involve both responsiveness and interdependence. Categorizing these relationships as “reciprocity” can be viewed as ignoring interdependence, but calling them ‘pseudo‐reciprocity’ is confusing because stability also comes from the cooperative investments being conditional on returns. Rather than conceptualizing cooperation intodiscrete categories, it is more insightful to imagine a coordinate system with responsiveness and interdependence ascontinuous dimensions. One can ask: To what degree is helping behavior responsive to the partner's behavior? And to what degree does the helper inherently benefit from the receiver's survival or reproduction? The amounts of responsiveness and interdependence will often be hard to estimate, but both are unlikely to be zero. Identifying their relative importance, and how that changes over time, would greatly clarify the nature of cooperative relationships.
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Modeling Random Networks with Heterogeneous Reciprocity
Reciprocity, or the tendency of individuals to mirror behavior, is a key measure that de- scribes information exchange in a social network. Users in social networks tend to engage in different levels of reciprocal behavior. Differences in such behavior may indicate the existence of communities that reciprocate links at varying rates. In this paper, we de- velop methodology to model the diverse reciprocal behavior in growing social networks. In particular, we present a preferential attachment model with heterogeneous reciprocity that imitates the attraction users have for popular users, plus the heterogeneous nature by which they reciprocate links. We compare Bayesian and frequentist model fitting techniques for large networks, as well as computationally efficient variational alternatives. Cases where the number of communities is known and unknown are both considered. We apply the presented methods to the analysis of Facebook and Reddit networks where users have non- uniform reciprocal behavior patterns. The fitted model captures the heavy-tailed nature of the empirical degree distributions in the datasets and identifies multiple groups of users that differ in their tendency to reply to and receive responses to wallposts and comments.
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- Award ID(s):
- 2210735
- PAR ID:
- 10540992
- Publisher / Repository:
- Journal of Machine Learning Research (JMLR)
- Date Published:
- Journal Name:
- Journal of machine learning research
- Volume:
- 25
- ISSN:
- 1533-7928
- Page Range / eLocation ID:
- 1-40
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Reciprocally patterned behavior is widespread in animals in the wild, but experimental evidence has been frustratingly inconsistent. Contrary to earlier contentions that this inconsistency is because reciprocity in non‐human species is a rare or fragile effect, recent authors have argued that the evidence suggests that reciprocity is widespread, that it often relies on cognitive mechanisms that are common across species, and is potentially an important factor in animals' daily lives. Another possible explanation for its apparent rarity, then, is that due to experimental studies' (intentionally) structured environment, they can lack the appropriate context to promote and support reciprocity. Focusing on outcomes from experimental reciprocal tasks in non‐human primates, I consider several factors that may be important, including the identity of the interactors and their relationship to one another, whether there is free choice of partners, whether the individuals are interacting directly, the timing of the interaction, the commodity involved, whether individuals have a reason to reciprocate, and the equity of the interaction. Clarifying the role of each of these factors will help improve experimental tasks and the social and ecological contexts that promote reciprocity.more » « less
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