Schools of fish, schools of thought

Kate Shaw enters a report in the science section of Wired on a paper that modeled decision-making in animal groups: “How ignorance could improve group decisions.” The paper itself by Iain Couzin and colleagues was in Science Couzin:uninformed:2011. Jevin West and Carl Bergstrom authored a companion perspective piece in Science explicating some of the paper’s findings. Here’s the paper’s abstract:

Conflicting interests among group members are common when making collective decisions, yet failure to achieve consensus can be costly. Under these circumstances individuals may be susceptible to manipulation by a strongly opinionated, or extremist, minority. It has previously been argued, for humans and animals, that social groups containing individuals who are uninformed, or exhibit weak preferences, are particularly vulnerable to such manipulative agents. Here, we use theory and experiment to demonstrate that, for a wide range of conditions, a strongly opinionated minority can dictate group choice, but the presence of uninformed individuals spontaneously inhibits this process, returning control to the numerical majority. Our results emphasize the role of uninformed individuals in achieving democratic consensus amid internal group conflict and informational constraints.

In other words, they have generated an agent-based model where each individual may have a marginal effect on group behavior relative to an “intensity” parameter, and the group’s decision is dictated by the collective center of gravity. “Uninformed” in the title is a misnomer; the study examines what happens to the group as individuals with little or no bias (that is, low “intensity”) are added to the group. Adding a high fraction of such individuals tends to reduce the influence of a small minority of individuals with an intense bias. In other words, the addition of low-bias individuals in the model skews the group decision in favor of a low-intensity majority.

Not surprising; the model generates the results expected given the assumptions. The study’s most interesting aspect is its application of the model to a problem of schooling in fish.

So why do so many of the press accounts of this study claim that it shows that “ignorance” can support democratic decisions? The “uninformed” individuals in the model lack information only in the sense that they lack a strong preference. In no other sense does information come into the model, other than as a measure of decision bias. This is “information” more or less in the sense that someone can “ask the audience” on “Who Wants to Be a Millionaire?” The contestant basically has to hope that a minority of the audience knows the correct answer, while the majority has no bias toward a false answer.

I’ve been thinking a lot about modern human origins lately, as I’m finishing up an e-book project. For many years I have worked very closely with the details in this area, really pushing up my sleeves and getting into both the genetic and morphological aspects of the problem. What always struck me was how the “scientific consensus” emerged in favor of an Out-of-Africa replacement hypothesis, and against the multiregional evolution hypothesis. The protagonists on either side of the modern human origins controversy didn’t really change very much over time. There were few high-profile “defections” from one side to the other. Initially, many of the best-known paleoanthropologists and geneticists sat on the fence. After all, few people work so directly with the evidence of modern human origins, when there is a debate it is reasonable to be cautious. But over a decade, like wildebeest waiting to jump into the crocodile-infested river, paleoanthropologists and geneticists whose work has little to do with modern human origins began to tip in favor of the replacement scenario.

They jumped too soon.

But why? I’ve been tackling this question: How did the majority of paleoanthropologists and human geneticists get this one so wrong?

I feel so fortunate to have been engaged in this problem, because it says so much about the process of science. Science is always a process where progress requires an opinionated minority to recruit support among peers who are not specialists in the same area. Such a minority may forge consensus through consistent and repeated demonstration of facts. More likely – as in the case of modern human origins, where new evidence was often equivocal – a motivated minority will apply a broader range of rhetorical strategies. Over the years, I saw people pull out every trick in the book to persuade the uncommitted to their point of view.

Rapid visual processing allows schooling fish to signal and comprehend the direction of movement within milliseconds. Scientists signal each other through their publications, grant reviews, and the press. It takes a lot longer for scientists to school.