Reasoning 631the theories are general ones that, in principle, can be applied
to any task, regardless of content.
Verbal Comprehension Theory
This theory is similar to the theory of mental models in the
initial inference steps a reasoner is expected to follow in in-
terpreting a reasoning task (i.e., constructing an initial model
of the premises and attempting to deduce a conclusion from
the initial model). Unlike the theory of mental models,
however, verbal comprehension theory does not propose that
people search for alternative models of task information.
Polk and Newell (1995), the originators of verbal compre-
hension theory, have proposed that people draw conclusions
automaticallyfrom information as part of their everyday
efforts at communication. In deductive reasoning tasks, how-
ever, when a conclusion is not immediately obvious, Polk
and Newell have suggested that people attempt to interpret
the task information differently until they are able to draw the
proper conclusion. Interpretation and reinterpretation define
reasoning, according to verbal comprehension theory, and
not the search for alternative models, as in mental model the-
ory. In spite of this alleged dissimilarity between verbal com-
prehension theory and mental model theory, it is not entirely
clear how the iterative interpretation process differs from the
search for models.
Polk and Newell (1995) have suggested that people com-
mit errors on deductive tasks because “linguistic processes
cannot be adapted to a deductive reasoning task instanta-
neously” (p. 534). That is, reasoning errors occur because
people’s comprehension processes are adapted to everyday
situations and tasks and not to deductive tasks that require
specific and formal interpretations.
Polk and Newell (1995) have presented a computational
model of categorical syllogistic reasoning based on verbal
comprehension theory that accounts for some standard find-
ings in the psychological literature. The computational
model, VR, produces regularities commonly and robustly ob-
served in human studies of syllogistic reasoning. For exam-
ple, whereas people, on average, answer correctly 53% of
categorical syllogism problems, VR generates correct an-
swers to an average of 59% of such problems. Also, whereas
people, on average, construct valid conclusions that match
theatmosphereor surface similarities of the premises on 77%
of categorical syllogism problems, VR generates similar con-
clusions on 93% of the problems.
Verbal comprehension theory can only be used to account
for reasoning on tasks that supply the reasoner with all the in-
formation he or she will need to reach a conclusion (Polk &
Newell, 1995). For this reason, this theory cannot be used to
explain how Oedipus might have solved the sphinx’s riddle,
unless we can find out what additional information Oedipus
used to solve the riddle. If we assume that Oedipus supplied
additional information, then how did Oedipus select the addi-
tional information? This is the same question we asked when
considering syntactic rule theory and mental model theory.
The sphinx’s riddle, as with so many of the problems people
face in everyday situations, requires the consideration of in-
formation beyond that presented in the problem statement.
Any theory that fails to outline how this search for additional
information occurs is hampered in its applicability to every-
day reasoning.
Verbal comprehension theory has additional limitations.
One criticism of the theory is that it fails to incorporate findings
that show the use of nonverbal methods of reasoning, such as
spatial representations, to solve categorical and linear syllo-
gisms (Evans, 1989; Evans, Newstead, et al., 1993; Ford,
1995; Galotti, 1989; Sternberg, 1980a, 1980b, 1981). For ex-
ample, Ford (1995) found that some individuals used primarily
verbal methods to solve categorical syllogisms, whereas other
individuals used primarily spatial methods to solve categorical
syllogisms. Individuals employing spatial methods constructed
a variant of Euler circles to evaluate conclusions derived from
categorical syllogisms. Moreover, in studies of linear syllo-
gisms (i.e., logical tasks about relations between entities),
researchers reported that participants created visual, mental
arrays of both the items and the relations in the linear syllo-
gisms in the process of evaluating conclusions (for a review
see Evans, Newstead, et al., 1993). Verbal comprehension
theory is also ambiguous as to whether verbal comprehension
operates at the level of strategies or at the level of cognitive
architecture. Polk and Newell (1995) described verbal reason-
ing as a strategy that involves the linguistic processes of enco-
ding and reencoding, but some linguistic processes are more
automatic than controlled (see Evans, 2000). If verbal reason-
ing is to be viewed as a strategy, then future treatments of the
theory might need to identify the specific linguistic processes
that are controlled by the reasoner and how this control is
achieved.Evolutionary TheoriesAccording to evolutionary theories, domain-specific reason-
ing mechanisms have evolved to help human beings meet
specific environmental needs (Cosmides & Tooby, 1996).Social Contract TheoryUnlike most of the previous theories discussed that ad-
vance domain-general methods of reasoning, social contract