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presented in Table 8.4 "The Representativeness Heuristic". Let’s say that you went to a hospital,
and you checked the records of the babies that were born today. Which pattern of births do you
think you are most likely to find?
Table 8.4 The Representativeness Heuristic
List A List B
6:31 a.m. Girl 6:31 a.m. Boy
8:15 a.m. Girl 8:15 a.m. Girl
9:42 a.m. Girl 9:42 a.m. Boy
1:13 p.m. Girl 1:13 p.m. Girl
3:39 p.m. Boy 3:39 p.m. Girl
5:12 p.m. Boy 5:12 p.m. Boy
7:42 p.m. Boy 7:42 p.m. Girl
11:44 p.m. Boy 11:44 p.m. Boy
Using the representativeness heuristic may lead us to incorrectly believe that some patterns of observed events are
more likely to have occurred than others. In this case, list B seems more random, and thus is judged as more likely
to have occurred, but statistically both lists are equally likely.Most people think that list B is more likely, probably because list B looks more random, and thus
matches (is “representative of”) our ideas about randomness. But statisticians know that any
pattern of four girls and four boys is mathematically equally likely. The problem is that we have
a schema of what randomness should be like, which doesn’t always match what is
mathematically the case. Similarly, people who see a flipped coin come up “heads” five times in
a row will frequently predict, and perhaps even wager money, that “tails” will be next. This
behavior is known as the gambler’s fallacy. But mathematically, the gambler’s fallacy is an
error: The likelihood of any single coin flip being “tails” is always 50%, regardless of how many
times it has come up “heads” in the past.
Our judgments can also be influenced by how easy it is to retrieve a memory. The tendency to
make judgments of the frequency or likelihood that an event occurs on the basis of the ease with
which it can be retrieved from memory is known as the availability heuristic (MacLeod &