Social vs. Logical Brain

Suppose a catalogue says that parcels with yellow labels are wrapped in paper. Now suppose a repair club requires anyone who borrows a sewing machine to have staffed a repair session. Both rules connect two facts. But in the first case you’re checking whether a description is true, and in the second you’re checking whether someone met a requirement. Does having a reason for the rule change which evidence you look for?

Peter Wason used four-card problems to study how people check a conditional rule. On each card, you know one fact and have to decide whether the other fact matters. Abstract reasoning comes into play when the features have no familiar connection. A letter and a number, for example, can follow a rule even when nothing about the letter explains the number. That makes the wording of the rule your main guide.

Leda Cosmides and John Tooby studied reasoning about exchanges in which access to a benefit depends on meeting a condition. At a repair club, access to shared equipment and a turn helping out have roles that are familiar from everyday life. A precaution can also make a rule meaningful. A lab might require goggles when a particular machine is running because it can send debris into the air. Laurence Fiddick, Cosmides, and Tooby investigated how people reason about social exchanges and precautions in versions of the four-card task.

The test mixes ten abstract problems, ten social contracts, and ten precautions. A score of 70% in a context means that you picked the exact set of required cards on seven of its ten questions. A missed card and an extra card both cost the exact-match point, but they tell you different things about which evidence you thought mattered. Reflective thinking can help you work through those differences. The averages marked on the chart come from adults tested by Valerie Stone, Leda Cosmides, John Tooby and colleagues in 2002, who solved about 34% of abstract problems, 70% of social contracts, and 71% of precautions. Their average Social Brain Index works out to about 68.

Start with the three accuracy scores. The Social Brain Index summarizes one comparison, between your social and abstract scores. An index of 50 can mean that you solved all ten questions in each of those sets or that you solved none in either. Your overall count tells you how often you got the exact answer across all 30 questions. Differences of ten percentage points within a context are differences of just one question.

This is an experimental reasoning profile for one session. The question sets have not been empirically matched for difficulty. Differences can reflect the wording, familiarity with the task, or the context itself. The profile provides no population ranking, IQ score, or neurological diagnosis.

References

• Wason, P. C. (1968). Reasoning about a rule. Quarterly Journal of Experimental Psychology, 20(3), 273–281. doi:10.1080/14640746808400161
• Cosmides, L. (1989). The logic of social exchange: Has natural selection shaped how humans reason? Studies with the Wason selection task. Cognition, 31(3), 187–276. doi:10.1016/0010-0277(89)90023-1
• Cosmides, L., & Tooby, J. (1989). Evolutionary psychology and the generation of culture, part II: Case study: A computational theory of social exchange. Ethology and Sociobiology, 10(1–3), 51–97. doi:10.1016/0162-3095(89)90013-7
• Stone, V. E., Cosmides, L., Tooby, J., Kroll, N., & Knight, R. T. (2002). Selective impairment of reasoning about social exchange in a patient with bilateral limbic system damage. Proceedings of the National Academy of Sciences, 99(17), 11531–11536. doi:10.1073/pnas.122352699
• Fiddick, L., Cosmides, L., & Tooby, J. (2000). No interpretation without representation: The role of domain-specific representations and inferences in the Wason selection task. Cognition, 77(1), 1–79. doi:10.1016/S0010-0277(00)00085-8

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