Human Factors in Simple and Complex Systems, Second Edition, 2nd Edition

11

Solving Problems and

Making Decisions

Like any goal-directed activity, thinking can be done well or badly. Thinking that is done well is thinking

of the sort that achieves its goals.

—J. Baron (2000)

INTRODUCTION

Complicated problem-solving and decision-making processes are engaged for all sorts of human

activities. You must make decisions about things as simple as what clothes to put on in the morning

and as complex as how to raise your children. Your decisions can have long-lasting consequences.

The CEO of a company co uld decide to expand based on an overestimate of the company’s financial

strength, which may result in bankruptcy. This in turn would result in the loss of many jobs and

have devastating consequences on the local economy. Similarly, a government’s decision to enter

into war will result in loss of life, economic hardship, and aftereffects of varying types that carry far

into the future. Scientists have tried to understand how human reasoning and decision making take

place so that poor decisions can be prevented.

Consider the operator of a human–machine system. To operate the system effectively, he or she

must comprehend system information and decide on appropriate actions. There are two ways that

the operator can control the system (Torenvliet & Vicente, 2006). The first mode of operation will

be used when the system is operating in a familiar and predictable way. Under these circumstances,

the operator can contr ol the system with very little effort, relying on well-practiced responses to the

system’s behavior (skill-based performance; see Chapter 3). The operator will face difficulty when

system information indicates that an unusual condition has developed, requiring that the operator

change to the second mode of operation. In this mode, the operator will need to make decisions

based on his reasoning about the system state. This reasoning may involve recall of information

from sema ntic or episodic memory (rule-based performance), or formulating a novel solution by

integrating several different sources of information (knowledge-based performance).

For example, most of a pilot’s efforts in flying an airplane involve monitoring the instruments in

the cockpit. This does not require a great deal of mental effort. Only when the instruments indicate

that a problem has occurred must the pilot engage in any effortful problem solving or decision

making. When the pilot determines that an emergency has occurred, he or she must integrate

information from the many visual and auditory displays in the cockpit, diagnose the nature of the

emergency, and decide on the actions he or she should take in response. Yet, as we have discussed

in the previous chapters, the pilot’s capacity for processing such information is limited, and he or she

may make a bad decision even though he or she is well-trained and well-intentioned.

This chapter examines how people reason about and choose between different actions. There are

two ways to describe how people make decisions: normative an d descriptive. A normative model

specifies those choices that a rational person should make under ideal circumstances. However, as

Johnson-Laird (1983, p. 133) observed, ‘‘Human reasoners often fail to be rational. Their limited

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