Optimal evidence accumulation on social networks

A fundamental question in biology is how organisms integrate sensory and social evidence to make decisions. However, few models describe how both these streams of information can be combined to optimize choices. Here we develop a normative model for collective decision making in a network of agents performing a two-alternative forced choice task. We assume that rational (Bayesian) agents in this network make private measurements, and observe the decisions of their neighbors until they accumulate sufficient evidence to make an irreversible choice. As each agent communicates its decision to those observing it, the flow of social information is described by a directed graph. The decision-making process in this setting is intuitive, but can be complex. We describe when and how the absence of a decision of a neighboring agent communicates social information, and how an agent must marginalize over all unobserved decisions. We also show how decision thresholds and network connectivity affect group evidence accumulation, and describe the dynamics of decision making in social cliques. Our model provides a bridge between the abstractions used in the economics literature and the evidence accumulator models used widely in neuroscience and psychology.

The Process of Social Identity Development in Adolescent High School Choral Singers

The purpose of this grounded theory study was to describe the process of adolescent choral singers’ social identity development within three midsized, midwestern high school mixed choirs. Forty-nine interviews were conducted with 36 different participants. Secondary data sources included memoing, observations, and interviews with the choir teachers. The data analysis revealed an eight-stage process beginning with the student’s choice to audition and remain involved to the final stage, a desire to give back to the community. The central phenomenon of social identity was identified as team. Contextual conditions, including time, intensity, and size of group, strengthened participant experiences substantively. Social cliques and egos emerged as intervening conditions that impeded social identity development. Several individuals influenced participant social identity including peers, parents, school and community members, as well as the choir teacher. A temporal matrix is presented as well as propositions illustrating the development of social identity.

Social cliques in male northern muriquis Brachyteles hypoxanthus

Analyses of spatial relationships and social interactions provide insights into the social structure of animal societies and the ways in which social preferences among and between dyads affect higher order social relationships. In this paper we describe the patterns of spatial associations and social interactions among adult male northern muriquis in order to evaluate the dynamics of their social networks above the dyadic levels. Systematic observations were made on the 17 adult males present in a multi-male/multi-female group from April 2004 through February 2005, and in July 2005. Analyses of their spatial relationships identified two distinct male cliques; some adult males (called “N” males) were more connected to the females and immatures than other adult males (“MU” males), which were more connected to one another. Affiliative interactions were significantly higher among dyads belonging to the same clique than to different cliques. Although frequencies of dyadic agonistic interactions were similarly low among individuals within and between cliques, MU males appeared to be subordinate to N males. Nonetheless, there were no significant differences in the copulation rates estimated for MU males and N males. Mutual benefits of cooperation between MU and N cliques in intergroup encounters might explain their ongoing associations in the same mixed-sex group [Current Zoology 58 (2): 342–352, 2012].

The impact of background category information on the creation of social cliques: The role of need for cognitive closure and decisiveness

The impact of background category information on the creation of social cliques: The role of need for cognitive closure and decisiveness This article focuses on the role of need for cognitive closure in the process of mental model creation about social relations (i.e. social cliques). We assumed that high (vs. low) need for closure participants tend to rely on background category information when forming social cliques. We predicted that this tendency to employ categorical information as a mental aid, used in order to form social cliques, would be efficient in simple task structures (where category information overlaps with the mental model structure) but would lead to increased error rates in complex task structures (where category information is inconsistent with the model structure). The results confirmed our predictions, showing especially strong effects for the decisiveness component of need for closure. The importance of individual differences in need for closure and decisiveness in social reasoning is discussed.