A short note on Evans' criticism of reasoning experiments and his matching response hypothesis

Toward a Statistical Theory of Reasoning

It is argued that the observed variability of responding in reasoning tasks might usefully be described by mathematical models based on stochastic processes. The data of a number of experiments employing Wason's selection task are reanalysed and it is shown that selection probabilities of individual cards are statistically independent. This is consistent with a class of simple stochastic models and renders conventional “insight” explanations of the data unparsi-monious.

A provisional stochastic model is formulated and subjected to a limited parametric test with reasonably satisfactory results. Some general directions for future research along these lines are suggested.

Formulation and Experimental Verification of Models in Propositional Reasoning

In Evans (1977) an experiment of Evans and Lynch (1973) based on Wason's selection task is re-analysed. We reformulated the model proposed by Evans as a state model and extended it to a new model by means of which the data of Evans and Lynch (1973), of Manktelow and Evans (1979), and of our own experiments can be explained. The new model is based on a falsification state, a verification state and a matching state.

Linguistic Factors in Reasoning

An experiment is reported which attempts to demonstrate the effects of manipulating two linguistic variables on a propositional reasoning task, one relating to the linguistic form of the logical rule, and the other to the presence and absence of negative components. The results are discussed in relation to Evans' (1972a) distinction between interpretational and operational factors in reasoning. Problems arising from the application of this distinction are discussed in detail.

Linguistic and Psychometric Factors in Propositional Reasoning

An experiment is reported which demonstrates the effects of linguistic and psychometric factors on adults’ performance on a propositional reasoning task. The three linguistic factors were the semantic content in which the logical rule was embedded, the linguistic form of the logical rule, and the polarity of the major premise of the logical arguments. The two psychometric factors were the mode of response and the order of presentation of the different types of content. The results showed that the linguistic factors had a pronounced effect on adults’ propositional reasoning abilities, whereas the influence of the psychometric factors was negligible. These findings are discussed in relation to operational and interpretational factors in reasoning.

On the Strategies that Blacks Employ in Deductive Reasoning

Over the past two decades, Wason's Four-Card Selection Task has attracted such a large amount of research and has generated such varied, interesting, and controversial results that it has come to be regarded as a standard paradigm for looking at how people reason deductively. Nevertheless, this article, which replicates Griggs and Cox's (1983) second experiment with a sample of 192 undergraduate college students, reports the first systematic study of the strategies that Black Americans use in the selection task. The results largely parallel those reported by Griggs and Cox as well as those that have been reported by other researchers. Still, the present results do differ in a number of ways from prior findings. We report an atypically high rate of accuracy for the standard version of the selection task. Also, the effect of problem content on processing strategy is curiously small, and its structure is unprecedented. On balance, the results of this study challenge monolithic notions of cognitive development that universally ascribe deficits in reasoning ability to Blacks. Some Blacks, notably those researched here, appear to acquire conceptual rules for logical reasoning that are as powerful and as fallible as any developed by people in Western, literate societies. Future research should explore the etiology of individual differences in reasoning ability and proclivities among Blacks.

Confirmation and matching biases in hypothesis testing

A number of investigators have claimed that subjects show confirmation bias on a variety of reasoning tasks. However, subjects who were classified as “confirming” had often selected evidence that could have falsified their hypothesis. In this study we present a novel task in which each piece of evidence is either falsifying or confirming, but not both. This task is similar in structure to Wason's (1966) 4-card task and its negated variant (Evans & Lynch, 1973); hence subjects were asked to perform these two tasks for comparison purposes. Some subjects also provided thinking-aloud protocols, allowing a test of the Johnson-Laird and Wason (1970) information processing model. Subjects were found who showed severe confirmation bias by selecting only evidence that could corroborate, but not falsify, their hypotheses. Several subjects even retained their hypotheses when presented with clearly falsifying evidence. The tendency to show confirmation bias was significantly greater in first-year undergraduates than in more educated subjects. A revised definition of confirmation bias is offered to clarify subjects’ reasons for their selections. In addition to evidence of confirmation bias, support was found for the matching bias model (Wason & Evans, 1975; Evans, 1977), emphasizing the need for sensitivity to individual differences.