The influence of belief bias on syllogistic reasoning
The syllogistic evaluation task paradigm requires participants to assess whether
a conclusion is logically determined by its premises. The inability to ignore
beliefs when attempting to comply with this requirement is the phenomenon
known as 'belief bias'. This research programme primarily examines this
phenomenon and is motivated by conflicting accounts of how it arises. This
research also examines the relative believability of the logical quantifiers
which are used to construct the syllogistic task.
Current theories of belief bias differ in respect of whether the premises
or the conclusion are thought to guide the reasoning process. Explicit attempts
to focus participants' attention on the conclusion or the premises indicated
that either method of reasoning was plausible. Subsequent research
demonstrated that these methods of reasoning are fairly paradigm specific.
Participants appear to utilise the premises to guide the reasoning process only
when there is no conclusion to evaluate (the production task paradigm). The
presence of the conclusion tends to evoke conclusion based reasoning and in
turn tends to promote a greater reliance on beliefs. In general, across the
experiments participants appeared to be fairly competent at evaluating
conclusions. However, their responses appeared to be based on whether a
conclusion was consistent with the premises as opposed to whether it was
logically determined by them. Belief bias actually appeared to have a beneficial
effect on logical reasoning as the presence of unbelievable conclusions
appeared to motivate participants to search for the logically correct response.
The Mental Model theory of reasoning provided a useful framework in
which to describe the results. However, additional assumptions were needed to
accommodate the notion, that when presented with a conclusion, participants
utilise it to guide the construction of a mental representations of the premises.