De-confusing the THOG problem: the Pythagorean solution.

Sources of facilitation for Needham and Amado's (1995) Pythagoras version of Wason's THOG problem were systematically examined in three experiments with 174 participants. Although both the narrative structure and figural notation used in the Pythagoras problem independently led to significant facilitation (40-50% correct), pairing hypothesis generation with either factor or pairing the two factors together was found to be necessary to obtain substantial facilitation (> 50% correct). Needham and Amado's original finding for the complete Pythagoras problem was also replicated. These results are discussed in terms of the "confusion theory" explanation for performance on the standard THOG problem. The possible role of labelling as a de-confusing factor in other versions of the THOG problem and the implications of the present findings for human reasoning are also considered.

Elementary, my dear Wason: the role of problem representation in the THOG task.

The present study was concerned with Wason's THOG problem, a hypothetico-deductive reasoning task for which performance over the past 20 years has typically been very poor (< 20% correct). We examined the hypothesis that incorporating a quasi-visual context into the problem statement would make both the binary, symmetric tree structure and solution principle of the THOG task clearer and thus facilitate performance. A version of O'Brien et al.'s (Q J Exp Psychol 42A:329-351) Blackboard THOG problem, that specifies each branch of the tree by describing a specific location for each possible color-shape combination, was used to test this hypothesis. Substantial facilitation was both observed (68% correct) and replicated (73% correct), and it was also shown that it is necessary to provide a representation of both sides of the tree to obtain this level of facilitation. The implications of these results for human deductive reasoning are considered.

Darwinian algorithms and the Wason selection task: a factorial analysis of social contract selection task problems.

In four experiments with 760 subjects, the present study examined Cosmides' Darwinian algorithm theory of reasoning: specifically, its explanation of facilitation on the Wason selection task. The first experiment replicated Cosmides' finding of facilitation for social contract versions of the selection task, using both her multiple-problem format and a single-problem format. Experiment 2 examined performance on Cosmides' three main social contract problems while manipulating the perspective of the subject and the presence and absence of cost-benefit information. The presence of cost-benefit information improved performance in two of the three problems while the perspective manipulation had no effect. In Experiment 3, the cost-benefit effect was replicated; and performance on one of the three problems was enhanced by the presence of explicit negatives on the NOT-P and NOT-Q cards. Experiment 4 examined the role of the deontic term "must" in the facilitation observed for two of the social contract problems. The presence of "must" led to a significant improvement in performance. The results of these experiments are strongly supportive of social contract theory in that cost-benefit information is necessary for substantial facilitation to be observed in Cosmides' problems. These findings also suggest the presence of other cues that can help guide subjects to a deontic social contract interpretation when the social contract nature of the problem is not clear.

Integrating verbal quantitative information in linear orderings.

Subjects learned and answered questions about four-term linear orderings described in paragraphs of text. Spacing along the dimension employed was varied by using verbal quantifiers ("just barely," "moderately," and "very much"). After learning the quantitative information, performance on ordinal information varied as a function of the quantitative difference between terms in the ordering. Reaction time was faster for large quantitative differences than for small quantitative differences. This result indicates that vague verbal quantitative information is integrated into the memory representation for an ordering and that such quantitative information does affect test performance.

The role of test procedure in linguistic integration studies.

The effects of type of recognition test procedure were studied in a Bransford and Franks (1971) integration paradigm. Subjects received a two-alternative forced-choice recognition test or a modified "forced-choice" test in which all the sentences for each idea set were presented at once and the "old" sentences had to be identified. Contrary to the usual Bransford and Franks results, in which a yes-no, one-sentence-at-a-time recognition procedure is employed, the ability to discriminate "old" sentences from "new" sentences was clearly observed. A bias for selecting more complex sentences, however, was found for the modified "forced-choice" procedure. A prototype learning model is described to account for these results and previous data.

Semantic memory: a bibliography, 1968-1975.

Semantic memory research is briefly described. Then a bibliography of 105 published references in semantic memory, calendar years, 1968-1975, is presented.

Recognition memory for deducible information.

Recent research in language comprehension indicates a constructive encoding process in which the linguistic input is transformed into some more general semantic structure which is stored. In attempting to characterize the nature of such structures, some conflicting findings have been observed for paragraphs which describe similar set-theoretic relations, linear orderings and set inclusions. While the linear ordering research supports the constructivist theory, the set inclusion work does not. The set inclusion studies, however, employed true-false tests and not the usual recognition tests. The present study investigated the processing of set inclusion paragraphs in a self-paced study/recognition test paradigm. Results supported the constructivist theory and were contrary to predictions based upon the previous set inclusion research. Subjects were unable to differentiate between presented information and unpresented deducible information. These results were discussed in terms of accuracy constraints of different tasks on memorial performance and a possible interaction of Type of Test by Universal Quantification.

Logical processing of set inclusion relations in meaningful text.

The present experiments attempted to resolve some recent conflicting findings in cognitive structure research between processing linear ordering and set inclusion relations described in meaningful paragraphs of text. In a self-paced study-test paradigm, college students studied such paragraphs. Definite processing differences were found for the two set-theoretic relations. Set inclusion test results were found to be due to faulty logical processing and not to memory retrieval problems. Subjects made invalid conversions of universally quantified statements and failed to make valid transitive inferences between such statements. This failure was found to be an increasing function of the distance separating the two terms in the set inclusion. No such problems were observed for linear orderings. The usual distance function was found: Accuracy on test questions about the ordering was an increasing function of the distance between the terms in the question. Results similar to those for linear orderings were observed for set inclusions when subjects were given special instructions about the validity and invalidity of symmetric and transitive inferences.