Robert X. D. Hawkins

Bootstrap Methods for the Empirical Study of Decision-Making and Information Flows in Social Systems

We characterize the statistical bootstrap for the estimation of information- theoretic quantities from data, with particular reference to its use in the study of large-scale social phenomena. Our methods allow one to preserve, approximately, the underlying axiomatic relationships of information theory—in particular, consistency under arbitrary coarse-graining—that motivate use of these quantities in the first place, while providing reliability comparable to the state of the art for Bayesian estimators. We show how information-theoretic quantities allow for rigorous empirical study of the decision-making capacities of rational agents, and the time-asymmetric flows of information in distributed systems. We provide illustrative examples by reference to ongoing collaborative work on the semantic structure of the British Criminal Court system and the conflict dynamics of the contemporary Afghanistan insurgency.

Conducting real-time multiplayer experiments on the web

Group behavior experiments require potentially large numbers of participants to interact in real time with perfect information about one another. In this paper, we address the methodological challenge of developing and conducting such experiments on the web, thereby broadening access to online labor markets as well as allowing for participation through mobile devices. In particular, we combine a set of recent web development technologies, including Node.js with the Socket.io module, HTML5 canvas, and jQuery, to provide a secure platform for pedagogical demonstrations and scalable, unsupervised experiment administration. Template code is provided for an example real-time behavioral game theory experiment which automatically pairs participants into dyads and places them into a virtual world. In total, this treatment is intended to allow those with a background in non-web-based programming to modify the template, which handles the technical server–client networking details, for their own experiments.

Anti-Nepotism's Ghost: Attitudes of Administrators Toward Hiring Professional Couples

Laws and policies are often the formalization of attitudes. The attitudes that originally led to the policy continue even when the policy no longer exists. We felt the anti-nepotism policies, declared discriminatory by HEWs Office of Civil Rights, were still in effect in the attitudes of college and university faculty. To test this, we surveyed the chairpersons of departments of psychology and sociology concerning their attitudes toward hiring a professional couple in their department. Responses to the question “Overall, how likely is it you would support the hiring of a professional couple?” indicated opposition by 37% of the chairpersons, neutrality by 25%, and support by 38%. When asked to list comments under four headings—advantages to department, disadvantages to department, professional advantages to couple, and professional disadvantages to couple—we found that supporters were more likely than opposers to mention advantages to the department and to the couple and that opposers were more likely than supporters to mention disadvantages to the department and to the couple. The types of comments made by the chairpersons may be useful to academic couples wishing to work together. “When James J. Gibson, a psychologist, moved from Smith College to Cornell University in 1948, his wife, Eleanor, also a psychologist, applied for a teaching job in her husbands department. Sixteen years later, she was hired.… “When Janet Taylor Spence went to the University of Texas in 1964, she had to forego teaching in the psychology department because her husband was already employed there. Instead she moved into the educational psychology department… In 1967 her husband died and she moved into the psychology department. A year later, she was named department chairman.”

Path ensembles and a tradeoff between communication efficiency and resilience in the human connectome

Computational analysis of communication efficiency of brain networks often relies on graph-theoretic measures based on the shortest paths between network nodes. Here, we explore a communication scheme that relaxes the assumption that information travels exclusively through optimally short paths. The scheme assumes that communication between a pair of brain regions may take place through a path ensemble comprising the k-shortest paths between those regions. To explore this approach, we map path ensembles in a set of anatomical brain networks derived from diffusion imaging and tractography. We show that while considering optimally short paths excludes a significant fraction of network connections from participating in communication, considering k-shortest path ensembles allows all connections in the network to contribute. Path ensembles enable us to assess the resilience of communication pathways between brain regions, by measuring the number of alternative, disjoint paths within the ensemble, and to compare generalized measures of path length and betweenness centrality to those that result when considering only the single shortest path between node pairs. Furthermore, we find a significant correlation, indicative of a trade-off, between communication efficiency and resilience of communication pathways in structural brain networks. Finally, we use k-shortest path ensembles to demonstrate hemispherical lateralization of efficiency and resilience.

The Formation of Social Conventions in Real-Time Environments.

Why are some behaviors governed by strong social conventions while others are not? We experimentally investigate two factors contributing to the formation of conventions in a game of impure coordination: the continuity of interaction within each round of play (simultaneous vs. real-time) and the stakes of the interaction (high vs. low differences between payoffs). To maximize efficiency and fairness in this game, players must coordinate on one of two equally advantageous equilibria. In agreement with other studies manipulating continuity of interaction, we find that players who were allowed to interact continuously within rounds achieved outcomes with greater efficiency and fairness than players who were forced to make simultaneous decisions. However, the stability of equilibria in the real-time condition varied systematically and dramatically with stakes: players converged on more stable patterns of behavior when stakes are high. To account for this result, we present a novel analysis of the dynamics of continuous interaction and signaling within rounds. We discuss this previously unconsidered interaction between within-trial and across-trial dynamics as a form of social canalization. When stakes are low in a real-time environment, players can satisfactorily coordinate ‘on the fly’, but when stakes are high there is increased pressure to establish and adhere to shared expectations that persist across rounds.

Can Two Dots Form a Gestalt? Measuring Emergent Features with the Capacity Coefficient

While there is widespread agreement among vision researchers on the importance of some local aspects of visual stimuli, such as hue and intensity, there is no general consensus on a full set of basic sources of information used in perceptual tasks or how they are processed. Gestalt theories place particular value on emergent features, which are based on the higher-order relationships among elements of a stimulus rather than local properties. Thus, arbitrating between different accounts of features is an important step in arbitrating between local and Gestalt theories of perception in general. In this paper, we present the capacity coefficient from Systems Factorial Technology (SFT) as a quantitative approach for formalizing and rigorously testing predictions made by local and Gestalt theories of features. As a simple, easily controlled domain for testing this approach, we focus on the local feature of location and the emergent features of Orientation and Proximity in a pair of dots. We introduce a redundant-target change detection task to compare our capacity measure on (1) trials where the configuration of the dots changed along with their location against (2) trials where the amount of local location change was exactly the same, but there was no change in the configuration. Our results, in conjunction with our modeling tools, favor the Gestalt account of emergent features. We conclude by suggesting several candidate information-processing models that incorporate emergent features, which follow from our approach.

Improving the Replicability of Psychological Science Through Pedagogy

Replications are important to science, but who will do them? One proposal is that students can conduct replications as part of their training. As a proof of concept for this idea, here we report a series of 11 preregistered replications of findings from the 2015 volume of Psychological Science, all conducted as part of a graduate-level course. As was expected given larger, more systematic prior efforts, the replications typically yielded effects that were smaller than the original ones: The modal outcome was partial support for the original claim. This work documents the challenges facing motivated students as they attempt to replicate previously published results on a first attempt. We describe the workflow and pedagogical methods that were used in the class and discuss implications both for the adoption of this pedagogical model and for replication research more broadly.

Learning to communicate about conceptual hierarchies

Natural languages provide speakers with remarkable flexibility in the labels they may use to refer to things (Brown, 1958). In addition to the combinatorial explosion of modifiers afforded by compositionality (Partee, 1995), we have a number of lexicalized nominal terms at our disposal. Dalmatian, dog, and animal can all truthfully be used to talk about the same Dalmatian at different levels of specificity, with one level of the conceptual hierarchy – the basic-level – generally privileged over the others (Rosch, Mervis, Gray, Johnson, & Boyes-Braem, 1976). How these overlapping meanings are learned, and why speakers choose different levels of specificity in different contexts, is increasingly accounted for by probabilistic models of pragmatic language use (e.g. Xu & Tenenbaum, 2007; Graf, Degen, Hawkins, & Goodman, 2016) but there remains a more fundamental evolutionary question: how do multiple levels of reference come to coexist in the lexicon to begin with? Our hypothesis, motivated both by classic work on concept representations and contemporary work on the selective pressures induced by communication, is that lexicalization of conceptual hierarchies is a function of (1) the structure and statistics of entities in the environment, and (2) the particular contexts in which communication occurs. In particular, we expect hierarchical lexica to form when features can be encoded as predictable clusters and communicative goals require distinctions to be drawn at multiple levels. To test this hypothesis, we designed a repeated reference game in which pairs of participants interactively created an artificial language to communicate with each other about objects in context (e.g. Winters, Kirby, & Smith, 2014; Galantucci & Garrod, 2011). In this game, participants were paired over the web and placed in a shared environment containing a grid of four objects (Fig. 1A) and a ‘chatbox’ to send messages from a pre-specified vocabulary of sixteen words (Fig. 1B). On each of ninety trials, one player — the ‘speaker’ — was privately shown a highlighted target object and allowed to send a single word to help their partner select this object 158