Biomedical subjects

Simon J Handley

Publications and source records attributed to Simon J Handley.

12 recordsLinked to original sources

PubMed2007

Reasoning and dyslexia: a spatial strategy may impede reasoning with visually rich information.

Bacon, Handley, and Newstead (2003, 2004), have presented evidence for individual differences in reasoning strategies, with most people seeming to represent and manipulate problem information using either a verbal or a spatial strategy. There is also evidence that individuals with dyslexia are inclined to conceptualise information in a visuo-spatial, rather than a verbal, way (e.g. von Károlyi et al., 2003). If so, we might expect a higher proportion of individuals with dyslexia to be spatial reasoners, compared with individuals who do not have dyslexia. The study reported here directly compared strategies reported by these two groups of participants on a syllogistic reasoning task. Moreover, problem content was manipulated so that reasoning across concrete and abstract materials could be compared. The findings suggest that whilst most individuals without dyslexia use a verbal strategy, reasoners with dyslexia do tend to adopt a spatial approach, though their performance is impaired with visually concrete materials. However, when reasoning with more abstract content, they perform comparably with non-dyslexic controls. The paper discusses these results in the light of recent research which has suggested that visual images may impede reasoning, and considers how individuals with dyslexia may differ from other reasoners.

Adult↗

PubMed2006

The probability of causal conditionals.

Conditionals in natural language are central to reasoning and decision making. A theoretical proposal called the Ramsey test implies the conditional probability hypothesis: that the subjective probability of a natural language conditional, P(if p then q), is the conditional subjective probability, P(q/p). We report three experiments on causal indicative conditionals and related counterfactuals that support this hypothesis. We measured the probabilities people assigned to truth table cases, P(pq), P(p notq), P( notpq) and P( notp notq). From these ratings, we computed three independent predictors, P(p), P(q/p) and P(q/ notp), that we then entered into a regression equation with judged P(if p then q) as the dependent variable. In line with the conditional probability hypothesis, P(q/p) was by far the strongest predictor in our experiments. This result is inconsistent with the claim that causal conditionals are the material conditionals of elementary logic. Instead, it supports the Ramsey test hypothesis, implying that common processes underlie the use of conditionals in reasoning and judgments of conditional probability in decision making.

Analysis of Variance↗

PubMed2006

The negated conditional: a litmus test for the suppositional conditional?

Under the suppositional account of conditionals, when people think about a conditional assertion, "if p then q," they engage in a mental simulation in which they imagine p holds and evaluate the probability that q holds under this supposition. One implication of this account is that belief in a conditional equates to conditional probability [P(q/p)]. In this paper, the authors examine a further implication of this analysis with respect to the wide-scope negation of conditional assertions, "it is not the case that if p then q." Under the suppositional account, nothing categorically follows from the negation of a conditional, other than a second conditional, "if p then not-q." In contrast, according to the mental model theory, a negated conditional is consistent only with the determinate state of affairs, p and not-q. In 4 experiments, the authors compare the contrasting predictions that arise from each of these accounts. The findings are consistent with the suppositional theory but are incongruent with the mental model theory of conditionals.

Adult↗

PubMed2005

Suppositions, extensionality, and conditionals: a critique of the mental model theory of Johnson-Laird And Byrne (2002).

P. N. Johnson-Laird and R. M. J. Byrne proposed an influential theory of conditionals in which mental models represent logical possibilities and inferences are drawn from the extensions of possibilities that are used to represent conditionals. In this article, the authors argue that the extensional semantics underlying this theory is equivalent to that of the material, truth-functional conditional, at least for what they term "basic" conditionals, concerning arbitrary problem content. On the basis of both logical argument and psychological evidence, the authors propose that this approach is fundamentally mistaken and that conditionals must be viewed within a suppositional theory based on what philosophical logicians call the Ramsey test. The Johnson-Laird and Byrne theory is critically examined with respect to its account of basic conditionals, nonbasic conditionals, and counterfactuals.

Cognition↗

PubMed2004

The story of some: everyday pragmatic inference by children and adults.

The statement, some elephants have trunks, is logically true but pragmatically infelicitous. Whilst some is logically consistent with all, it is often pragmatically interpreted as precluding all. In Experiments 1 and 2, we show that with pragmatically impoverished materials, sensitivity to the pragmatic implicature associated with some is apparent earlier in development than has previously been found. Amongst 8-year-old children, we observed much greater sensitivity to the implicature in pragmatically enriched contexts. Finally, in Experiment 3, we found that amongst adults, logical responses to infelicitous some statements take longer to produce than do logical responses to felicitous some statements, and that working memory capacity predicts the tendency to give logical responses to the former kind of statement. These results suggest that some adults develop the ability to inhibit a pragmatic response in favour of a logical answer. We discuss the implications of these findings for theories of pragmatic inference.

Adolescent↗

PubMed2004

Individual differences in deductive reasoning.

Three studies are reported, which examined individual differences in deductive reasoning as a function of intellectual ability and thinking style. Intellectual ability was a good predictor of logical performance on syllogisms, especially where there was a conflict between logic and believability. However, in the first two experiments there was no link between ability and performance on indicative selection tasks, in sharp contrast to previous research. This correlation did, however, return in the final study. Our data are consistent with the claim that the correlation with logical accuracy on abstract selection tasks is found primarily with participants of relatively high ability. At lower levels, pragmatically cued responses are given but those of slightly higher ability divorce the rule from the scenario and respond consistently (though incorrectly) across problems. Self-report questionnaires were generally poor predictors of performance, but a measure of the ability to generate alternative representations proved an excellent predictor. These results are consistent with a mental models approach to reasoning and also have implications for the debate about human rationality.

Adult↗

PubMed2004

Belief bias and figural bias in syllogistic reasoning.

Belief bias is the tendency to be influenced by the believability of the conclusion when attempting to solve a syllogistic reasoning problem. Figural bias is the tendency to be influenced by the order in which the information is presented in the premises when attempting to solve a syllogistic reasoning problem. When studied simultaneously they enable an investigation of whether participants' reasoning on the syllogistic reasoning task is guided by the conclusion (backward reasoning) or the premises (forward reasoning). Experiments 1 and 2 found evidence of belief bias but not figural bias on the syllogistic evaluation task paradigm. Experiments 3 and 4 found evidence of figural bias but not belief bias on the syllogistic production task paradigm. The findings highlight that different task characteristics influence performance dependent upon the nature of task presentation. These findings are discussed in the context of current theories of belief bias in syllogistic reasoning.

Cognition↗

PubMed2003

Conditionals and conditional probability.

The authors report 3 experiments in which participants were invited to judge the probability of statements of the form if p then q given frequency information about the cases pq, p not q, not pq, and not p not q (where not = not). Three hypotheses were compared: (a) that people equate the probability with that of the material conditional, 1 - P(p not q); (b) that people assign the conditional probability, P(q/p); and (c) that people assign the conjunctive probability P(pq). The experimental evidence allowed rejection of the 1st hypothesis but provided some support for the 2nd and 3rd hypotheses. Individual difference analyses showed that half of the participants used conditional probability and that most of the remaining participants used conjunctive probability as the basis of their judgments.

Color Perception↗

PubMed2002

Alternative antecedents, probabilities, and the suppression of fallacies in Wason's selection task.

Three experiments examined the influence of a second rule on the pattern of card selections on Wason's selection task. In Experiment 1 participants received a version of the task with a single test rule or one of two versions of the task with the same original test rule together with a second rule. The probability of q was manipulated in the two-rules conditions by varying the size of the antecedent set in the second rule. The results showed a significant suppression of q card and not-p card selections in the alternative-rule conditions, but no difference as a function of antecedent set size. In Experiment 2 the size of the antecendent set in the two-rules conditions was manipulated using the context of a computer printing double-sided cards. The results showed a significant reduction of q card selections in the two-rules conditions, but no effect of p set size. In Experiment 3 the scenario accompanying the rule was manipulated, and it specified a single alternative antecedent or a number of alternative antecedents. The q card selection rates were not affected by the scenario manipulation but again were suppressed by the presence of a second rule. Our results suggest that people make inferences about the unseen side of the cards when engaging with the task and that these inferences are systematically influenced by the presence of a second rule, but are not influenced by the probabilistic characteristics of this rule. These findings are discussed in the context of decision theoretic views of selection task performance (Oaksford & Chater, 1994).

Choice Behavior↗

PubMed2002

Conditional reasoning and the Tower of Hanoi: the role of spatial and verbal working memory.

This paper reports a study that investigated the relationships between verbal and spatial measures of working memory capacity and performance on the Tower of Hanoi and a conditional reasoning task. Four working memory measures were included, a simple word span, a simple spatial span, a complex verbal span and a complex spatial span. The participants were 70 undergraduate students. Solution time on the Tower of Hanoi task correlated highly with both measures of spatial memory capacity, but not with the verbal working memory spans. In contrast, logical performance on the conditional reasoning task correlated highly with the complex verbal working memory span, but not with the spatial spans. A confirmatory factor analysis of the data elicited a best-fit model comprising a correlated spatial and verbal factor. The results are interpreted in the context of recent work that suggests a dissociation between spatial and verbal resources at the level of the central executive.

Cognition↗

PubMed2002

Generating alternatives: a key component in human reasoning?

According to mental models theory, a key aspect of deductive reasoning is the production of alternative models that can falsify provisional conclusions. In the present paper, the possibility is investigated that there are individual differences in the ability to produce alternative models. The results indicate that some people do not proceed beyond the first model when they reason with syllogisms but that others do. Furthermore, the ability to generate alternatives can be independently measured by asking participants to generate different representations of pairs of premises. These findings support the predictions of mental models theory and also indicate the potential importance of alternatives generation as a measure of individual differences in processing style.

Adolescent↗

PubMed2002

Background beliefs in Bayesian inference.

We report five experiments in which the role of background beliefs in social judgments of posterior probability was investigated. From a Bayesian perspective, people should combine prior probabilities (or base rates) and diagnostic evidence with equal weighting, although previous research shows that base rates are often underweighted. These experiments were designed so that either piece of information was supplied either by personal beliefs or by presented statistics, and regression analyses were performed on individual participants to assess the relative influence of information. We found that both prior probabilities and diagnostic information significantly influenced judgments, whether supplied by beliefs or by statistical information, but that belief-based information tended to dominate the judgments made.

Bayes Theorem↗