Ninth Bartlett Memorial Lecture. Thinking as a Skill

Linguistic Determinants of Bias in Conditional Reasoning

An experiment is reported to test the hypothesis that a non-logical tendency known as “matching bias”, which occurs in conditional reasoning tasks, is linguistically determined. It is argued that the bias occurs because items which are not mentioned in the conditional rules appear to be “irrelevant” since they do not conform to the linguistic “topic” of the sentence. Logical cases can, however, be produced which always “match” the items named in the rules by introducing explicit negatives into the descriptions of the instances. As predicted, when this was done, the usual “matching bias” effect was significantly reduced as compared with the normal use of affirmative instances which implicitly negate components of the rules. The results show that linguistic factors have an important influence on subjects’ processing of problem information, and not simply on their initial representations of the logical rules.

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.

The Misleading Concept of Cognitive Competences

Descriptions of action/cognition can be given at various different levels. For heuristic purposes, three levels are identified: the behavioural, the information-processing and the level of summarizing what an individual is capable of (competences). In cognitive psychology competences, principles, rules or strategies are commonly attributed to individuals by way of `explaining' their accomplishments. The present paper argues that such attributions have value mainly as a form of shorthand, but otherwise tend to mislead. Various controversies concerning the attribution of cognitive competences (inference-making, number competence, mnemonic strategies, theory of mind) are analysed and are shown to be empirically unresolvable because they involve the conflating of different levels of description. It is suggested that the temptation to make attributions of cognitive competences follows from three habits of mind; these involve the nominalist fallacy of reifying classificatory terms, and the mistaking of the reified entity for an individual endowment. A similar argument has been made in the case of `intelligence' by Howe (1988, 1990). The most effective challenge to the idea of attributing competences to individuals comes, in fact, from within cognitive psychology itself, yet the idea persists and even thrives. By citing examples of research which clearly demonstrate the misleading nature of the idea of individual competences, it is intended to encourage future avoidance of it.

Rational belief

There is a tension between normative and descriptive elements in the theory of rational belief. This tension has been reflected in work in psychology and decision theory as well as in philosophy. Canons of rationality should be tailored to what is humanly feasible. But rationality has normative content as well as descriptive content.

A number of issues related to both deductive and inductive logic can be raised. Are there full beliefs – statements that are categorically accepted? Should statements be accepted when they become overwhelmingly probable? What is the structure imposed on these beliefs by rationality? Are they consistent? Are they deductively closed? What parameters, if any, does rational acceptance depend on? How can accepted statements come to be rejected on new evidence

Should degrees of belief satisfy the probability calculus? Does conformity to the probability calculus exhaust the rational constraints that can be imposed on partial beliefs? With the acquisition of new evidence, should beliefs change in accord with Bayes' theorem? Are decisions made in accord with the principle of maximizing expected utility? Should they be?

A systematic set of answers to these questions is developed on the basis of a probabilistic rule of acceptance and a conception of interval-valued logical probability according to which probabilities are based on known frequencies. This leads to limited deductive closure, a demand for only limited consistency, and the rejection of Bayes' theorem as universally applicable to changes of belief. It also becomes possible, given new evidence, to reject previously accepted statements.

Facilitative interactions of model- and experience-based processes: implications for type and flexibility of representation

People are often taught using a combination of instruction and practice. In prior research, we have distinguished between model-based knowledge (i.e., acquired from explicit instruction) and experience-based knowledge (i.e., acquired from practice), and have argued that the issue of how these types of knowledge (and associated learning processes) interact has been largely neglected. Two experiments explore this issue using a dynamic control task. Results demonstrate the utility of providing model-based knowledge before practice with the task, but more importantly, suggest how this information improves learning. Results also show that learning in this manner can lead to "costs" such as slowed retrieval, and that this knowledge may not always transfer to new task situations as well as experientially acquired knowledge. Our findings also question the assumption that participants always acquire a highly specific "lookup" table representation while learning this task. We provide an alternate view and discuss the implications for theories of learning.

Effects of model-based and memory-based processing on speed and accuracy of grammar string generation

Learners are able to use 2 different types of knowledge to perform a skill. One type is a conscious mental model, and the other is based on memories of instances. The authors conducted 3 experiments that manipulated training conditions designed to affect the availability of 1 or both types of knowledge about an artificial grammar. Participants were tested for both speed and accuracy of their ability to generate letter sequences. Results indicate that model-based training leads to slow accurate responding. Memory-based training leads to fast, less accurate responding and highest achievement when perfect accuracy was not required. Evidence supports participants' preference for using the memory-based mode when exposed to both types of training. Finally, the accuracy contributed by model-based training declined over a retention interval.

Acquisition of intellectual and perceptual-motor skills

Recent evidence indicates that intellectual and perceptual-motor skills are acquired in fundamentally similar ways. Transfer specificity, generativity, and the use of abstract rules and reflexlike productions are similar in the two skill domains; brain sites subserving thought processes and perceptual-motor processes are not as distinct as once thought; explicit and implicit knowledge characterize both kinds of skill; learning rates, training effects, and learning stages are remarkably similar for the two skill classes; and imagery, long thought to play a distinctive role in high-level thought, also plays a role in perceptual-motor learning and control. The conclusion that intellectual skills and perceptual-motor skills are psychologically more alike than different accords with the view that all knowledge is performatory.

Two modes of mental representation and problem solution in syllogistic reasoning

In this paper, the theory of syllogistic reasoning proposed by Johnson-Laird (1983, 1986; Johnson-Laird & Bara, 1984; Johnson-Laird & Byrne, 1991) is shown to be inadequate and an alternative theory is put forward. Protocols of people attempting to solve syllogistic problems and explaining to another person how they reached their conclusions were obtained. Two main groups of subjects were identified. One group represented the relationship between classes in a spatial manner that was supplemented by a verbal representation. The other group used a primarily verbal representation. A detailed theory of the processes for both groups is given.

Domain-specific reasoning: social contracts, cheating, and perspective change

What counts as human rationality: reasoning processes that embody content-independent formal theories, such as propositional logic, or reasoning processes that are well designed for solving important adaptive problems? Most theories of human reasoning have been based on content-independent formal rationality, whereas adaptive reasoning, ecological or evolutionary, has been little explored. We elaborate and test an evolutionary approach. Cosmides' (1989) social contract theory, using the Wason selection task. In the first part, we disentangle the theoretical concept of a "social contract" from that of a "cheater-detection algorithm". We demonstrate that the fact that a rule is perceived as a social contract--or a conditional permission or obligation, as Cheng and Holyoak (1985) proposed--is not sufficient to elicit Cosmides' striking results, which we replicated. The crucial issue is not semantic (the meaning of the rule), but pragmatic: whether a person is cued into the perspective of a party who can be cheated. In the second part, we distinguish between social contracts with bilateral and unilateral cheating options. Perspective change in contracts with bilateral cheating options turns P & not-Q responses into not-P & Q responses. The results strongly support social contract theory, contradict availability theory, and cannot be accounted for by pragmatic reasoning schema theory, which lacks the pragmatic concepts of perspectives and cheating detection.

The logic of social exchange: has natural selection shaped how humans reason? Studies with the Wason selection task

In order to successfully engage in social exchange--cooperation between two or more individuals for mutual benefit--humans must be able to solve a number of complex computational problems, and do so with special efficiency. Following Marr (1982), Cosmides (1985) and Cosmides and Tooby (1989) used evolutionary principles to develop a computational theory of these adaptive problems. Specific hypotheses concerning the structure of the algorithms that govern how humans reason about social exchange were derived from this computational theory. This article presents a series of experiments designed to test these hypotheses, using the Wason selection task, a test of logical reasoning. Part I reports experiments testing social exchange theory against the availability theories of reasoning; Part II reports experiments testing it against Cheng and Holyoak's (1985) permission schema theory. The experimental design included eight critical tests designed to choose between social exchange theory and these other two families of theories; the results of all eight tests support social exchange theory. The hypothesis that the human mind includes cognitive processes specialized for reasoning about social exchange predicts the content effects found in these experiments, and parsimoniously explains those that have already been reported in the literature. The implications of this line of research for a modular view of human reasoning are discussed, as well as the utility of evolutionary biology in the development of computational theories.

Probabilistic judgements in deluded and non-deluded subjects

An experiment is described in which deluded subjects were compared with a non-deluded psychiatric control group and a normal control group on a probabilistic inference task. Deluded subjects were found to request less information before reaching a decision and to express higher certainty levels than either control group. They also exhibited over-confidence on estimates of the probability of a future event.

Delusion. A false personal belief based on incorrect inference about external reality and firmly sustained in spite of what almost everyone else believes and in spite of what constitutes incontrovertible and obvious proof or evidence to the contrary. The belief is not one ordinarily accepted by other members of the person's subculture. [American Psychiatric Association, 1980]