The need to explain

How do reasoners deal with inconsistencies? James (1907) believed that the rational solution is to revise your beliefs and to do so in a minimal way. We propose an alternative: You explain the origins of an inconsistency, which has the side effect of a revision to your beliefs. This hypothesis predicts that individuals should spontaneously create explanations of inconsistencies rather than refute one of the assertions and that they should rate explanations as more probable than refutations. A pilot study showed that participants spontaneously explain inconsistencies when they are asked what follows from inconsistent premises. In three subsequent experiments, participants were asked to compare explanations of inconsistencies against minimal refutations of the inconsistent premises. In Experiment 1, participants chose which conclusion was most probable; in Experiment 2 they rank ordered the conclusions based on their probability; and in Experiment 3 they estimated the mean probability of the conclusions' occurrence. In all three studies, participants rated explanations as more probable than refutations. The results imply that individuals create explanations to resolve an inconsistency and that these explanations lead to changes in belief. Changes in belief are therefore of secondary importance to the primary goal of explanation.     

Naïve deontics: a theory of meaning, representation, and reasoning

Deontic assertions concern what one ought to do, may do, and ought not to do. This paper proposes a theory of their meanings and of how these meanings are represented in mental models. The meanings of deontic assertions refer to sets of permissible and impermissible states. An experiment corroborated the ability of individuals to list these states. The most salient were those corresponding to the mental models of the assertions. When individuals reason, they rely on mental models, which do not make all states explicit. The theory predicts the most frequent conclusions drawn from deontic premises. It also predicts the occurrence of illusory inferences from assertions of permission, i.e., inferences that seem highly plausible but that are in fact invalid. Assertions of prohibitions, according to the theory, should reduce the illusions. Further experiments corroborated these predictions.     

Procedural semantics

The aim of this paper is to present an outline of a theory of semantics based on the analogy between natural and computer programming languages. A unified model of the comprehension and production of sentences is described in order to illustrate the central “compile and execute” metaphor underlying prodecural semantics. The role of general knowledge within the lexicon, and the mechanism mediating selectional restrictions, are re-analyzed in the light of the procedural theory.     

The three-term series problem

There are three apparently conflicting theories about the process by which an individual solves three-term series problems, i.e. problems such as ‘A is better than B, B is better than C, who is best?’ An information-processing analysis is presented which reveals that the IMAGE model of De Soto, Handel and London (1965) can easily be reconciled with the LINGUISTIC model of Clark (1969). However, an examination of some slight inconsistencies among the empirical findings reveals that such a reconciliation may be misleading. It is suggested instead that there is likely to be a change of approach during an experimental session. The individual initially may utilize a procedure analogous to the IMAGE model, modified to incorporate one of the principles of Hunter's (1957) OPERATIONAL model. Subsequently, as the result of practice, he may develop a procedure more analogous to the LINGUISTIC model.     

Book reviews

SANDERS, A. F. (Ed.). Attention and Performance III. Amsterdam: North Holland Publishing Company. 1970. Pp. viii + 442. (Price not known.)

CORCORAN, D. W. J. Pattern Recognition. Harmondsworth: Penguin Books Ltd. 1971. Pp. 223. £0.50.

SCHRIER, A. M. and STOLLNITZ, F. (Eds.) Behaviour of Nonhuman Primates Vol. III. New York: Academic Press Inc. 1971. £4.45.

KINTSCH, W. Learning, Memory, and Conceptual Processes. New York: Wiley and Sons. 1970. Pp. 498. £4.40.

MORTON, J. (Ed.) Biological and Social Factors in Psycholinguistics. London: Logos Press. 1971. Pp. 215. £3.50.

RITCHIE RUSSELL, W. The Traumatic Amnesius. London: Oxford University Press. Pp. 84. £2.00.

MILLER, N. E. Selected Papers. Chicago: Aldine Publishing. 1971. Pp. 874. £15.00.

SUTHERLAND, N. S. AND MACKINTOSH, N. J. Mechanisms of Animal Discrimination Learning. New York: Academic Press. 1971. Pp. 559. $18.50.

FURCHTGOTT, E. (Ed.). Pharmacological and Biophysical Agents and Behavior. New York: Academic Press. 1971. Pp. xii+402. $14.50.

EYSENCK, H. J., ARNOLD, W. AND MEILI,R. (Eds). Encyclopedia of Psychology. Volume I. London: Search Press. 1972. Pp. 396. £8.00.     

When negation is easier than affirmation

An experiment is reported which establishes that affirmative sentences are not always easier to grasp than negative sentences. The subjects had to make inferences from pairs of premises such as: “Either John is intelligent or he is rich. John is not rich”. The task was reliably easier when the second premise was explicitly negative (as in the example) than when it was an affirmative (“John is poor”). It was most difficult when the negative occurred in the disjunctive premise and was denied by an affirmative (e.g. “John is intelligent or he is not rich. John is rich”). It is argued that it is simpler to establish that two statements are mutually inconsistent when one is the explicit negation of the other, but that the natural function of the negative is to deny.     

Modal reasoning, models, and Manktelow and Over.

Manktelow and Over (1991) argue that their studies of Wason's selection task favor explanations of deontic reasoning based on mental models, but that such theories need to incorporate utilities. This theoretical note proposes a simpler explanation of the phenomena: subjects in the selection task consider only those cards that are explicitly represented in their models of the conditional, and so insight into the task depends on constructing fully explicit models. Such models for modal conditionals of the form, If p occurs then q may occur are: [formula: see text] Each line denotes a separate model, and the models represent either what is possible, or, in the deontic interpretation, what is permissible. A deontic rule is accordingly violated by the contingency: [symbol: see text] p and q, for example the rule, "If you spend more than 100 pounds, then you may take a free gift" is violated by taking the free gift (q) but not spending more than 100 pounds ([symbol: see text] p). If the rule is interpreted as a bi-conditional, then the second of the models, p and [symbol: see text] q, is also now a violation, for example spending more than 100 pounds (p) but not getting the free gift ([symbol: see text] q). Manktelow and Over's instructions lead subjects to focus on one or other of the two sorts of violations of the rule. There is accordingly no need to introduce utilities into models in order to explain the phenomena.     

Propositional reasoning by model.

This article describes a new theory of propositional reasoning, that is, deductions depending on if, or, and, and not. The theory proposes that reasoning is a semantic process based on mental models. It assumes that people are able to maintain models of only a limited number of alternative states of affairs, and they accordingly use models representing as much information as possible in an implicit way. They represent a disjunctive proposition, such as "There is a circle or there is a triangle," by imagining initially 2 alternative possibilities: one in which there is a circle and the other in which there is a triangle. This representation can, if necessary, be fleshed out to yield an explicit representation of an exclusive or an inclusive disjunction. The theory elucidates all the robust phenomena of propositional reasoning. It also makes several novel predictions, which were corroborated by the results of 4 experiments.