Thinking and Deciding

176 HYPOTHESIS TESTING
Both of these tests are equally informative and equally valuable (Baron, 1985a,
p. 143). If we keep the honey and change everything else, the cake will most likely
turn out as it did the first time (whatever way that was), if our hypothesis is true, and
the cake will turn out differently if our hypothesis is false. If we change only the
honey, the cake will turn out differently if our hypothesis is true, and the cake will
turn out as it did the first time if our hypothesis is false. The situations are completely
the same except for the reversal of “as it did before” and “differently.”
The reason the subjects choose different tests in the two cases is that they quite
legitimately are pursuing two goals: information and a good cake at the end of their
experiment. The effect of their desire for a good cake on their choice of how they
will test their hypothesis is harmless, in this case; either choice is a good one. In
other situations, the conflict of goals may not be so harmless. This is particularly
true when there is no real value in a “positive” result. For example, in the 2 4 6
task, the desire to obtain yes answers may inhibit subjects from thinking of tests that
would yield no as the answer if their favored hypothesis is true, which would in this
case be more informative. Subjects may like to hear the word “yes,” and physicians
may like to hear that a test result was “positive,” but these words have no value in
themselves. If we seek to hear them at the expense of obtaining real information, we
are very likely subverting the achievement of our goals.
Schwartz (1982) demonstrated the detrimental effects of seeking reward by asking
one group of subjects to try to earn rewards (nickels) by pressing two buttons
(L and R, forLeft and Right) in a certain pattern. Pressing the button moved a light
through a five-by-five matrix of squares, starting in the upper left-hand corner; pressing
L moved the light down one square, and presGsing R moved it one square to
the right. A second group of subjects was asked to discover the rule that leads to
reward (although they were not given monetary rewards for correct sequences of
button presses). The rule itself was based simply on the relative number of Ls and
Rs; any sequence of four Ls and four Rs could produce it (probabilistically). Such a
sequence moved the light from upper left to lower right without running off the edge.
Subjects in the reward group usually developed “stereotyped” sequences, such
as LLLLRRRR. At the end of the experiment, when they were asked to give the
rule, these subjects stated exactly the pattern they had been using, and they often
felt that this pattern was necessary, the only one that would work. The discovery
group usually did discover the rule. When the reward group took part in a second
experiment with the same instructions as the discovery group, they were less likely to
discover the rule than was the discovery group. Apparently their ability to discover
the rule was inhibited by their tendency to work for reward rather than information.
The reduction of the motivation to discover rules seems to have carried over to a new
task.
In a later experiment, Schwartz (1988) examined the finding that stereotypy led
to the confusion of sufficiency with necessity. After pretraining in either the “reward”
or “rule” condition, subjects were asked to solve problems analogous to the four-card
problem discussed in Chapter 4 but using the same apparatus that Schwartz had used
earlier (the matrix and buttons). Subjects were asked to test rules concerning either