Understanding Psychology (10th Ed)

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If you had diffi culty with the problem, it was probably because you felt compelled 
to keep your lines within the grid. If you had gone outside the boundaries, however, 
you would have succeeded by using the solution shown in Figure 11 on page 263. 
(The phrase “thinking outside the box”—a term commonly used in business today to 
encourage creativity—stems from research on overcoming the constraining effects of 
mental set.) 
INACCURATE EVALUATION OF SOLUTIONS 
When the United States invaded Iraq, it did so because governmental leaders believed 
that Saddam Hussein possessed weapons of mass destruction that posed a threat to 
the security of the Middle East. The belief proved false, and a bipartisan U.S. Senate 
committee later found that the belief was based on a fl awed interpretation of intel-
ligence information. According to the Senate committee, government leaders had 
made up their minds early on about the presence of weapons of mass destruction, 
and they ignored contradictory evidence and focused more on information that sup-
ported their view (U.S. Senate Select Committee on Intelligence, 2004). 
The mistake made by governmental leaders exemplifi es  confi rmation bias  in 
which problem solvers favor initial hypotheses and ignore contradictory information 
that supports alternative hypotheses or solutions. Even when we fi nd evidence that 
contradicts a solution we have chosen, we are apt to stick with our original hypothesis.
Confi rmation bias occurs for several reasons. For one thing, because rethinking 
a problem that appears to be solved already takes extra cognitive effort, we are apt 
to stick with our fi rst solution. For another, we give greater weight to subsequent 
information that supports our initial position than to information that is not sup-
portive of it (Evans & Feeney, 2004; Parmley, 2007; Rassin, 2008).