Introduction

The psychological fields of reasoning and of decision making are reported in different literatures, mostly by different authors and with little cross-reference. Is this just a matter of research traditions, or are the cognitive processes involved fundamentally different? On the face of it, a reasoning task is significantly different from a decision task. In the study of deductive reasoning, for example, subjects may be presented with the premises of some argument and asked whether or not a conclusion follows. For example, a subject may be asked to evaluate a syllogism such as

1. No A are B

2. Some B are not C

3. Therefore, some C are not A

and to indicate whether or not the conclusion follows. This is presumed to involve a process of reasoning from the premises which may or may not support the conclusion. If the subject has deductive competence – discussed below – it should be possible for him or her to solve the problem set without further information. In this sense, deductive reasoning tasks can be viewed as a special case of well-defined problem-solving tasks, whose main purpose is to investigate people's ability to understand and apply logical principles.

Decision-making tasks, on the other hand, involve choices between actions and normally involve commitment to particular acts at one point in time, whose consequences will only later be apparent. A simple example might be deciding whether or not to place a bet on a horse.