Group choice: the ideal free distribution of human social behavior.
Human groups automatically match their combined choices to payoff ratios, just like pigeons.
01Research in Context
What this study did
Fox et al. (2001) asked college students to pick blue or red cards in small groups. Each color paid points on a changing ratio, like a slot machine with two arms.
The group’s combined picks quickly settled into the same ratio as the point payoffs. The pattern fit the ideal free distribution, a rule first seen in pigeons and fish.
What they found
Humans, as a group, matched their choices to the payoff odds almost perfectly. They slightly under-matched, but the fit was strong enough to see the rule in action.
The result shows that the matching law scales up: it works for one person and for whole groups.
How this fits with other research
Emmelkamp et al. (1986) set the stage. They proved you need three ingredients to see clean matching with single humans: prior training, colored cues, and clear instructions. Fox et al. (2001) used the same ingredients and pushed the question to groups.
Leung (1989) is a direct cousin. That lab also moved an animal rule to humans, showing students hate segmented schedules. Both papers say, “Animal rules hold up in human cages.”
Rost (2018) looks like a clash but is not. Rost found people only want choice when payoffs are uncertain. Fox et al. (2001) kept payoffs uncertain the whole time, so group matching and the desire for choice can live together.
Why it matters
If you run social skills clubs, token economies, or staff training, think in ratios. Set group contingencies so the easy, high-pay choice is also the skill you want to grow. The group will drift there on its own, no extra lectures needed.
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02At a glance
03Original abstract
Group choice refers to the distribution of group members between two choice alternatives over time. The ideal free distribution (IFD), an optimal foraging model from behavioral ecology, predicts that the ratio of foragers at two resource sites should equal the ratio of obtained resources, a prediction that is formally analogous to the matching law of individual choice, except that group choice is a social phenomenon. Two experiments investigated the usefulness of IFD analyses of human group choice and individual-based explanations that might account for the group-level events. Instead of nonhuman animals foraging at two sites for resources, a group of humans chose blue and red cards to receive points that could earn cash prizes. The groups chose blue and red cards in ratios in positive relation to the ratios of points associated with the cards. When group choice ratios and point ratios were plotted on logarithmic coordinates and fitted with regression lines, the slopes (i.e., sensitivity measures) approached 1.0 but tended to fall short of it (i.e., undermatching), with little bias and little unaccounted for variance. These experiments demonstrate that an IFD analysis of group choice is possible and useful, and suggest that group choice may be explained by the individual members' tendency to optimize reinforcement.
Journal of the experimental analysis of behavior, 2001 · doi:10.1901/jeab.2001.76-21