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Despite previous research suggesting that participants' negative and positive emotions can impair and facilitate reasoning performance, a recent study proposes that the emotional content of the mood induction materials may not be crucial in eliciting these phenomena--deontic selection task performance is as poor when these materials are neutral as when they are negative (Perham and Oaksford 2006). We extend this finding to syllogistic reasoning performance. Participants in the mood induction conditions (negative and neutral) verbally described their experiences in relation to twenty negative or neutral words whereas participants in the control condition received no such mood induction. Subsequent syllogistic reasoning performance was significantly poorer for both mood induction conditions yet only those in the negative mood induction condition showed a significant increase in anxiety. Results imply that the key mechanism involved in the impairment derives from the production of irrelevant thoughts and that these need not be linked to a positive or negative mood, thus 'not thinking' may actually help the reasoning process. Keywords Reasoning * Emotion * Irrelevant thoughts, Being in a negative mood, such as reporting feelings of anxiety and/or depression, can have both negative and positive effects on cognitive performance (see Blanchette and Richards 2010, for an [...]

Participants from an individualistic society (USA) were compared with participants from a collectivistic society (Turkey) in terms of moral reasoning and orientation (justice and care). A total of 396 undergraduates (203 U.S. students, 193 Turkish students) between the ages of 18 and 46 years were administered the original version of the Defining Issues Test and the Measure of Moral Orientation. Turkish participants received higher mean principled scores than did the U.S. participants, and female participants received higher mean principled scores than did male participants. Turkish participants also scored significantly higher on the justice and care orientations than U.S. participants, and female participants scored significantly higher on the justice and care orientations than male participants. DOI 10.2466/08.09.17.PR0.107.5.463-479

Geiger and Oberauer (2007) found that when asked to reason with conditionals, people are very sensitive to information about the relative frequency of exceptions to conditional rules and quite insensitive to the relative number of disabling conditions. They asked participants to rate their degree of certainty in a conclusion. In the following studies, we investigated the possibility that this kind of response encourages a more probabilistic mode of processing compared with the usual dichotomous response. In Study 1, participants were given a variant of the problems used by Geiger and Oberauer with either the same scaled response format or a dichotomous categorical response. The results with the scaled response were identical to those of Geiger and Oberauer. However, the results with the categorical response presented a very different profile. In Study 2, we presented similar problems using only frequency information, followed by a set of abstract conditional reasoning problems. The participants who performed better on the abstract problems showed a significantly different response profile than those who did worse on the abstract problems in the categorical response condition. No such difference was observed in the scaled response condition. These results show that response modality strongly affects the way in which information is processed in otherwise identical inferential problems and they are consistent with the idea that scaled responses promote a probabilistic mode of processing. doi: 10.3758/MC.38.4.485

Discriminating same from different collections of items is central to human thought and reasoning. Recent comparative research suggests that same--different discrimination behavior: is not uniquely human, does not require human language, is based on the variability of the collection of items, obeys fundamental psychophysical laws, and may be captured by quantitative models of the stimulus collection. The comparative study of same--different discrimination behavior sheds fresh light on the mechanisms and functions of abstract conceptualization. This study also has prompted the development of a theory--the Finding Differences Model--that successfully explains a wealth of findings in the comparative psychology of same-different discrimination behavior. Keywords: same-different discrimination, relational learning, concept learning, pigeons, baboons DOI: 10.1037/a0016327

An ongoing goal in the field of categorization has been to determine how objects' features provide evidence of membership in one category versus another. Well-known findings include that feature diagnosticity is a function of how often the feature appears in category members versus nonmembers, their perceptual salience, how features are used in support of inferences, and how observable features are related to other observable features. We tested how diagnosticity is affected by causal relations between observable and unobserved features. Consistent with our view of classification as diagnostic reasoning, we found that observable features are more diagnostic to the extent that they are caused by underlying features that define category membership, because the presence of the latter can be (causally) inferred from the former. Implications of these results for current views of conceptual structure and models of categorization are discussed.

Is human thought fully embedded in language, or do some forms of thought operate independently? To directly address this issue, we focus on inference-making, a central feature of human cognition. In a 3T fMRI study we compare logical inferences relying on sentential connectives (e.g., not, or, if ... then) to linguistic inferences based on syntactic transformation of sentences involving ditransitive verbs (e.g., give, say, take). When contrasted with matched grammaticality judgments, logic inference alone recruited 'core' regions of deduction [Brodmann area (BA) 10p and 8m], whereas linguistic inference alone recruited perisylvian regions of linguistic competence, among others (BA 21, 22, 37, 39, 44, and 45 and caudate). In addition, the two inferences commonly recruited a set of general 'support' areas in frontoparietal cortex (BA 6, 7, 8, 40, and 47). The results indicate that logical inference is not embedded in natural language and confirm the relative modularity of linguistic processes. fMRI | logic | reasoning | semantics | syntax

Contrary to what seems to have become established dogma in the behavioral sciences, the confirmational relevance of some data possibility D to a conjecture H should be indifferent to which of these two prospects we think of first. In particular, if ascertaining whether D is true would be a hypothetico-deductive test of hypothesis H were D's implication by H declared at outset, the confirmational relevance of D to H is not diminished by learning D before becoming aware that H implies it. Keywords: hypothesis testing; post-hoc reasoning; scientific knowledge; theory appraisal; evidence; confirmation

The author discusses the abductive theory of method (ATOM) by Brian Haig from a philosophical perspective, connecting his theory with a number of issues and trends in contemporary philosophy of science. It is argued that as it stands, the methodology presented by Haig is too permissive. Both the use of analogical reasoning and the application of exploratory factor analysis leave us with too many candidate theories to choose from, and explanatory coherence cannot be expected to save the day. The author ends with some suggestions to remedy the permissiveness and lack of normative force in ATOM, deriving from the experimental practice within which psychological data are produced. Keywords: scientific methodology; abduction; theory generation; theory development; underdetermination; exploratory factor analysis; analogical reasoning; Newman's problem; experimental interventions

Relational reasoning (A > B, B > C, therefore A > C) shares a number of similarities with numerical cognition, including a common behavioural signature, the symbolic distance effect. Just as reaction times for evaluating relational conclusions decrease as the distance between two ordered objects increases, people need less time to compare two numbers when they are distant (e.g., 2 and 8) than when they are close (e.g., 3 and 4). Given that some remain doubtful about such analogical representations in relational reasoning, we determine whether numerical cognition and relational reasoning have other overlapping behavioural effects. Here, using relational reasoning problems that require the alignment of six items, we provide evidence showing that the subjects' linear mental representation affects motor performance when evaluating conclusions. Items accessible from the left part of a linear representation are evaluated faster when the response is made by the left, rather than the right, hand and the reverse is observed for items accessible from the right part of the linear representation. This effect, observed with the prepositions to the left of and to the right of as well as with above and below, is analogous to the SNARC (Spatial Numerical Association of Response Codes) effect, which is characterized by an interaction between magnitude of numbers and side of response. Keywords: Relational reasoning; Transitive reasoning; Numerical cognition; SNARC.

In formal reasoning, the quantifier 'some' means 'at least one and possibly all.' In contrast, reasoners often pragmatically interpret 'some' to mean 'some, but not all' on both immediate-inference and Euler circle tasks. It is still unclear whether pragmatic interpretations can explain the high rates of errors normally observed on syllogistic reasoning tasks. To address this issue, we presented participants (reasoners) in the present experiments either standard quantifiers or clarified quantifiers designed to precisely articulate the quantifiers' logical interpretations. In Experiment 1, reasoners made significantly more logical responses and significantly fewer pragmatic responses on an immediate-inference task when presented with logically clarified as opposed to standard quantifiers. In Experiment 2, this finding was extended to a variant of the immediate-inference task in which reasoners were asked to deduce what followed from premises they were to assume to be false. In Experiment 3, we used a syllogistic reasoning task and observed that logically clarified premises reduced pragmatic and increased logical responses relative to standard ones, providing strong evidence that pragmatic responses can explain some aspects of the errors made in the syllogistic reasoning task. These findings suggest that standard quantifiers should be replaced with logically clarified quantifiers in teaching and in future research.

The ability to entertain possibilities and draw inferences about them is essential to human intelligence. We examine the hypothesis that conditional if--then statements trigger a mental simulation process in which people suppose the antecedent (if statement) to be true and evaluate the consequent (then statement) in that context. On the assumption that supposing an event to be true increases belief that the event has occurred or will occur, this hypothesis is consistent with the claim that evaluating a conditional will heighten belief in its antecedent more than in its consequent. Two experiments, employing conditionals of the form If animal A has property X, then animal B will have property X, in which X was a property that people could not readily relate to the animals, supported this claim. The effect was stronger following the evaluation of conditionals with dissimilar animal categories.

Associative and causal reasoning accounts are probably the two most influential types of accounts of causal reasoning processes. Only causal reasoning accounts predict certain asymmetries between predictive (i.e., reasoning from causes to effects) and diagnostic (i.e., reasoning from effects to causes) inferences regarding cue-interaction phenomena (e.g., the overshadowing effect). In the experiments reported here, we attempted to delimit the conditions under which these asymmetries occur. The results show that unless participants perceived the relevance of causal information to solving the task, predictive and diagnostic inferences were symmetrical. Specifically, Experiments 1A and 1B showed that implicitly stressing the relevance of causal information by having participants review the instructions favored the presence of asymmetries between predictive and diagnostic situations. In addition, Experiment 2 showed that explicitly stressing the relevance of causal information by stating the importance of the causal role of events after the instructions were given also favored the asymmetry.

Norenzayan, Smith, Jun Kim, and Nisbett (2002) investigated cultural differences in the use of intuitive versus formal reasoning in 4 experiments. Our comment concerns the 4th experiment where Norenzayan et al. reported that, although there were no cultural differences in accuracy on abstract logical arguments, Koreans made more errors than U.S. undergraduates in judging the logical validity of concrete arguments. Norenzayan et al. concluded that Koreans are less likely than European Americans to decontextualize an argument's content from its logical structure, as Koreans were more likely to consider the believability of the conclusion when assessing an argument's validity (a belief bias). Notably, Korean participants were more conservative (less likely to say an argument is valid) than European American participants when assessing arguments. An analysis of the average of the hit and correct rejection rates in each of the conditions (abstract, concrete-believable, concrete-nonbelievable) revealed that, contrary to conclusions of Norenzayan et al., European Americans were no better than Koreans at determining the validity of concrete deductive arguments with conclusions varying in believability.

According to current psychological models of deduction, people can draw inferences on the basis of information that they receive from different sources at different times. In 3 reading-comprehension experiments, the authors demonstrated that premises that appear far apart in a text (distant) are not accessed and are therefore not used as a basis for logical inferences (Experiment 1), unless the premises are reinstated by a contextual cue (Experiment 2). In Experiment 3, the authors investigated whether these deductions are then integrated into the reader's situation model of the text. The results are interpreted in terms of a collaboration between memory-based text processing and higher level schema-driven logical reasoning.

Syllogistic reasoning has been investigated as a general deductive process (Johnson-Laird & Byrne, 1991; Revlis, 1975; Rips, 1994). However, several studies have demonstrated the role of cognitive strategies in this type of reasoning. These strategies focus on the method used by the participants (Ford, 1995; Gilhooly, Logie, Wetherick, & Wynn, 1993) and strategies related to different interpretations of the quantified premises (Roberts, Newstead, & Griggs, 2001). In this paper, we propose that content (as well as individual cognitive differences) is an important factor in inducing a certain strategy or method for syllogistic resolution. Specifically, we suggest that syllogisms with a causal conditional premise that can be extended by an agency premise induce the use of a conditional method. To demonstrate this, we carried out two experiments. Experiment 1 provided evidence that this type of syllogism leads participants to draw the predicted conditional conclusions, in contrast with control content syllogisms. In Experiment 2, we demonstrated that the drawing of conditional conclusions is based on a causal conditional to an agent representation of the syllogism premises. These results support the role of content as inducing a particular strategy for syllogistic resolution. The implications of these results are discussed.

The authors suggest that decisions made from multiple pieces of evidence are performed by mechanisms of parallel constraint satisfaction, which are related to cognitive consistency theories. Such reasoning processes are bidirectional--decisions follow from evidence, and evaluations of the evidence shift toward coherence with the emerging decision. Using a factually complex legal case, the authors observed patterns of coherence shifts that persisted even when the distribution of decisions was manipulated (Study 1) and influenced by the participants' attitudes (Study 2). The evaluations of the evidence cohered with the preferred decision even when participants changed their preference (Study 3). Supporting the bidirectionality of reasoning, Study 4 showed that assigning participants to a verdict affected their evaluation of the evidence. Coherence shifts were observed also in related background knowledge. This research suggests that cognitive consistency theories should play a greater role in the understanding of human reasoning and decision making.

Dual-process theories come in many forms. They draw on the distinction between associative, heuristic, tacit, intuitive, or implicit processes (System 1) and rule-based, analytic, explicit processes (System 2). We present the results of contextual manipulations that have a bearing on the supposed primacy of System 1 (Stanovich & West, 2000). Experiment 1 showed that people who evaluated logically valid or invalid conditional inferences under a timing constraint (N = 56), showed a smaller effect of logical validity than did people who were not placed under a timing constraint (N = 44). Experiment 2 similarly showed that stressing the logical constraint that only inferences that follow necessarily are to be endorsed (N = 36) increased the size of the validity effect, as compared to that of participants (N = 33) given the standard instruction to make 'logical' inferences. These findings concur with the thesis in dual-processing frameworks that 'Rationality-2 processes' (Evans & Over, 1996), 'test procedures' (Chater & Oaksford, 1999), or 'conclusion validation processes' (Johnson-Laird & Byrne, 1991; Schroyens, Schaeken, & d'Ydewalle, 2001) serve to override the results of System 1 processes.

Theories of informal reasoning and critical thinking often maintain that everyday, informal arguments can be classified into types based on the specific organization that the premises or reasons enter into in their support for the conclusion (Snoeck Henkemans, 2000; Vorobej, 1995b). Three general types are identified: convergent, coordinately linked, and subordinately linked arguments. There has been no empirical research, however, to determine whether these structural distinctions have any psychological reality. In the first two of four experiments, college students were presented with premise pairs from larger, informal arguments and were asked to judge the nature of the relationship between the premises in a pair. The judgments involved applying 'tests' of linkage, subordination, and so on, that have been proposed in the theoretical literature on argument analysis (e.g., Walton, 1996a; Yanal, 1991). Results suggest that adults can effectively distinguish between linked (interdependent) and convergent relationships and can further distinguish between interdependencies that are full and those that are merely partial. Adults also distinguished between subordinate and nonsubordinate relations. Experiments 3 and 4 provide evidence that adults make use of information about argument structure in evaluating argument strength and in categorizing arguments. Experiment 4 further suggests that facility with macrostructure is only modestly related to deductive reasoning competence. Findings are framed in terms of a speculative account of how argument structure is identified and mentally represented.

Informal reasoning fallacies are arguments that, though they may seem persuasive, are not valid. The psychological aspect of informal reasoning fallacies, specifically the identification of factors that influence students' ability to identify fallacies, has not been the subject of empirical study. The aim of this study was to test the hypothesis that subjects' ability to identify fallacious arguments is associated with the representation of the argumentative text in the cognitive system. In the first experiment, we tested the hypothesis through a recall task. In the second experiment, we tested the hypothesis through a classification task. The results of the experiments confirm the research hypothesis and point to the role of argumentative structures in argumentation tasks.

Time plays a pivotal role in causal inference. Nonetheless most contemporary theories of causal induction do not address the implications of temporal contiguity and delay, with the exception of associative learning theory. Shanks, Pearson, and Dickinson (1989) and several replications (Reed, 1992, 1999) have demonstrated that people fail to identify causal relations if cause and effect are separated by more than two seconds. In line with an associationist perspective, these findings have been interpreted to indicate that temporal lags universally impair causal induction. This interpretation clashes with the richness of everyday causal cognition where people apparently can reason about causal relations involving considerable delays. We look at the implications of cause-effect delays from a computational perspective and predict that delays should generally hinder reasoning performance, but that this hindrance should be alleviated if reasoners have knowledge of the delay. Two experiments demonstrated that (1) the impact of delay on causal judgement depends on participants' expectations about the timeframe of the causal relation, and (2) the free-operant procedures used in previous studies are ill-suited to study the direct influences of delay on causal induction, because they confound delay with weaker evidence for the relation in question. Implications for contemporary causal learning theories are discussed.

This study was an investigation of the relationship between potential creativity--as measured by fluency scores on the Alternate Uses Test--and performance on Wason's 2-4-6 task. As hypothesized, participants who were successful in discovering the rule had significantly higher fluency scores. Successful participants also generated higher frequencies of confirmatory and disconfirmatory hypotheses, but a multiple regression analysis using the stepwise method revealed that the frequency of generating disconfirmatory hypotheses and fluency scores were the only two significant factors in task outcome. The results also supported earlier studies where disconfirmation was shown to play a more important role in the later stages of hypothesis testing. This was especially true of successful participants, who employed a higher frequency of disconfirmatory hypotheses after receiving feedback on the first announcement. These results imply that successful participants benefited from the provision of feedback on the first announcement by switching to a more successful strategy in the hypothesis-testing sequence.

When people evaluate categorical syllogisms, they tend to reject unbelievable conclusions and accept believable ones irrespective of their validity. Typically, this effect is particularly marked for invalid conclusions that are possible, but do not necessarily follow, given the premises. However, smaller believability effects can also be detected for other types of conclusion. Three experiments are reported here, in which an attempt was made to determine whether belief bias effects can manifest themselves on the relational inference task. Subjects evaluated the validity of conclusions such as William the Conqueror was king after the Pyramids were built (temporal task) or Manchester is north of Bournemouth (spatial task) with respect to their premises. All of the major findings for equivalent categorical syllogism tasks were replicated. However, the overall size of the main effect of believability appears to be related to task presentation, a phenomenon not previously identified for categorical syllogisms and which current theories of belief bias have difficulty explaining.

Medical specialists confronted with problems in their domain of expertise do not rely on intentional causal reasoning, using explicit principles or rules. Rather, reasoning is an automatic process, using knowledge in an encapsulated mode. Less clear is what happens when medical specialists encounter problems outside their specialties. To shed light on this issue, we asked cardiologists and pulmonologists to evaluate 4 clinical cases, 2 in the domain of cardiology and 2 in pulmonology. Their task was to study, diagnose, recall, and explain the signs and symptoms of the clinical case descriptions. The cardiologists and pulmonologists alike processed cases in their specialties faster and more accurately, but recall and pathophysiological explanations did not reveal significant differences. These results suggest that medical specialists do not process cases outside their specialties in a qualitatively different mode from cases within their specialties., Theories on the development of expertise suggest that experts, while solving problems within their domain of expertise, apply knowledge that is qualitatively different from that applied by intermediates or novices. [...]

Good informal arguments offer justification for their conclusions. They go wrong if the justifications double back, rendering the arguments circular. Circularity, however, is not necessarily a single property of an argument, but may depend on (a) whether the argument repeats an earlier claim, (b) whether the repetition occurs within the same line of justification, and (c) whether the claim is properly grounded in agreed-upon information. The experiments reported here examine whether people take these factors into account in their judgments of whether arguments are circular and whether they are reasonable. The results suggest that direct judgments of circularity depend heavily on repetition and structural role of claims, but only minimally on grounding. Judgments of reasonableness take repetition and grounding into account, but are relatively insensitive to structural role. Keywords: Reasoning; Argumentation

The authors investigated the relationship between reasoners' understanding of subjunctive conditionals (e.g., if p had happened, then q would have happened) and the inferences they were prepared to endorse. Reasoners who made a counterfactual interpretation of subjunctive statements (i.e., they judged the statement to imply that p and q did not happen) endorsed different inferences than those who did not. Those who made a counterfactual interpretation were more likely to (a) judge the situation in which p and q occurred to be inconsistent with the conditional statement and (b) make negative inferences such as modus tollens (i.e., ~q therefore ~p). These findings occurred with familiar and unfamiliar content, affirmative and negative conditionals, and conditional and biconditional relations.

Causal learning typically entails the problem of being confronted with a large number of potentially relevant statistical relations. One type of constraint that may guide the choice of appropriate statistical indicators of causality are assumptions about temporal delays between causes and effects. There have been a few previous studies in which the role of temporal relations in the learning of events that are experienced in real time have been investigated. However, human causal reasoning may also be based on verbally described events, rather than on direct experiences of the events to which the descriptions refer. The aim of this paper is to investigate whether assumptions about the temporal characteristics of the events that are being described also affect causal judgment. Three experiments are presented that demonstrate that different temporal assumptions about causal delays may lead to dramatically different causal judgments, despite identical learning inputs. In particular, the experiments show that temporal assumptions guide the choice of appropriate statistical indicators of causality by structuring the event stream (Experiment 1), by selecting the potential causes among a set of competing candidates (Experiment 2), and by influencing the level of aggregation of events (Experiment 3).

People tend to approach agreeable propositions with a bias toward confirmation and disagreeable propositions with a bias toward disconfirmation. Because the appropriate strategy for solving the four-card Wason selection task is to seek disconfirmation, the authors predicted that people motivated to reject a task rule should be more likely to solve the task than those without such motivation. In two studies, participants who considered a Wason task rule that implied their own early death (Study 1) or the validity of a threatening stereotype (Study 2) vastly outperformed participants who considered nonthreatening or agreeable rules. Discussion focuses on how a skeptical mindset may help people avoid confirmation bias both in the context of the Wason task and in everyday reasoning.

A series of recent studies showed that facilitation on the Wason Selection Task could be produced by perceived utilities. The present work was aimed at testing whether a similar factor could also be involved in human reasoning performance in the context of responsibility. We supposed that the motivation of the subject assuming responsibility is affected by normative goals. These goals prescribe the actions and the results to be achieved, also considering the different social roles. In this experiment the responses of different groups of subjects (N= 270) to a selection task were compared in two different conditions involving different responsibility contexts. The results show that the subjects' strategies in searching for possible violators depended on the condition (responsibility vs no responsibility). In particular, only in the context of responsibility were the performances elicited by conditional rules characterised by a falsification strategy.

Pilot work and 3 studies investigated the ways people explain the origins of attitudes. Study 1 examined the use of 3 dimensions (externality, rationality, emotionality) to explain the origin of people's own, in-group, and out-group attitudes. Attributions for own attitudes were the least externally and emotionally based and the most rationally based. By comparison with the out-group, less externality, less emotionality, and more rationality also were attributed to in-group attitudes. Studies 2 and 3 examined the effects of intergroup threat on attributions for in- and out-group attitude positions. Under high threat, more externality and emotionality but less rationality were attributed to out-group attitudes than under low threat. Intergroup differentiation mediated the difference between out-group attributions under high and low threat.

Although it is natural to suppose that visual mental imagery is important in human deductive reasoning, the evidence is equivocal. This article argues that reasoning studies have not distinguished between ease of visualization and ease of constructing spatial models. Rating studies show that these factors can be separated. Their results yielded four sorts of relations: (1) visuospatial relations that are easy to envisage visually and spatially, (2) visual relations that are easy to envisage visually but hard to envisage spatially, (3) spatial relations that are hard to envisage visually but easy to envisage spatially, and (4) control relations that are hard to envisage both visually and spatially. Three experiments showed that visual relations slow down the process of reasoning in comparison with control relations, whereas visuospatial and spatial relations yield inferences comparable with those of control relations. We conclude that irrelevant visual detail can be a nuisance in reasoning and can impede the process.

The authors argue that the ways in which people--scientists and laymen--use probabilistic reasoning is predicated on a set of often questionable assumptions that are implicit and frequently go untested. They relate to the correspondence between the terms of a theory and the observations used to validate the theory and to the implicit understandings of intention and prior knowledge that arise between the conveyer and the receiver of information. The authors show several ways in which the use of probabilistic reasoning rests on a priori commitments to a partitioning of an outcome space and demonstrate that there are many more assumptions underlying the use of probabilistic reasoning than are usually acknowledged. They unfold these assumptions to show how several different interpretations of the same results in behavioral decision theory and cognitive psychology are equally well supported by 'the facts.' They then propose a more comprehensive approach to mapping cognitive processes than those currently used, one that is based on the analysis of all of the relevant alternative interpretations presented in the article.

In multicausal abductive tasks a person must explain some findings by assembling a composite hypothesis that consists of one or more elementary hypotheses. If there are n elementary hypotheses, there can be up to [2.sup.n] composite hypotheses. To constrain the search for hypotheses to explain a new observation, people sometimes use their current explanation--the previous evidence and their present composite hypothesis of that evidence; however, it is unclear when and how the current explanation is used. In addition, although a person's current explanation can narrow the search for a hypothesis, it can also blind the problem solver to alternative, possibly better, explanations. This paper describes a model of multicausal abductive reasoning that makes two predictions regarding the use of the current explanation. The first prediction is that the current explanation is not used to explain new evidence if there is a simple (i.e., nondisjunctive, concrete) hypothesis to account for that evidence. The second prediction is that the current explanation is used when attempting to discriminate among several alternative hypotheses for new evidence. These hypotheses were tested in three experiments. The results are consistent with the second prediction: the current explanation is used when discriminating among alternative hypotheses. However, the first prediction--that the current explanation is not used when a simple hypothesis can account for new data--received only limited support. Participants used the current explanation to constrain their interpretation of new data in 46.5% of all trials. This suggests that context-independent strategies compete with context-dependent ones--an interpretation that is consistent with recent work on strategy selection during problem solving. Keywords: Abduction; Hypothesis generation; Cognitive modeling; Explanations, 1. Introduction Abduction is the problem of finding a best explanation for a set of observations (Josephson & Josephson, 1994; Peng & Reggia, 1990). It is an essential feature of [...]

Research presented concerns the 'belief bias' effect found in syllogistic reasoning, wherein subjects are more likely to produce or accept conclusions that they believe are true, in spite of their logical validity. A model to account for response biases is discussed.

Research presented concerns the cognitive complexity of the THOG problem, which involves hypothetico-deductive reasoning. Results are examined within the context of 'confusion theory.'

A mental models-based account of belief bias is presented, in which limitations on working memory play a key role. A series of experiments investigate belief bias in syllogistic reasoning in relation to working memory and metacognitive uncertainty.

The role of deductive inference in Wason's selection task has been examined in a series of three experiments. Topics include non-deductive accounts of Wason's task, deductive accounts of the task, how to suppress card choices on the task, and the evidence for deductive inference.

Studies show that the belief in one's control over the future provides a means of comprehending one's previous failures, instead of a model that relies on evaluative judgments. Reasons include that recollection of negative outcomes generates strong emotional responses that affect an individual's decisions more extensively than reasoning.

The effect of negative meanings on reasoning ability is examined, focusing on the relationship between conditional inferences and negative premises. Topics include mental models theory and inference rule theory, implicit and double negation, and matching bias.

Causal conditional reasoning is examined in two experiments, aimed to determine the relationship between perspective effect and causal reasoning. Topics include deontic logic, which is concerned with reasoning involving obligations and permissions, causal contexts, and social roles

This study examined whether participants were sensitive to variations in the quality of an experiment discussed by an expert witness and whether they used heuristic cues when evaluating the expert evidence. In the context of a hostile work environment case, different versions of the expert testimony varied the presence of heuristic cues (i.e., whether the expert' s research was generally accepted or ecologically valid) and evidence quality (i.e., the construct validity of the expert' s research). Men who heard expert testimony were more likely to find that the plaintiff's workplace was hostile than were men who did not hear the expert testimony; expert testimony did not influence women's liability judgments. Heuristic cues influenced participant evaluations of the expert testimony validity, but evidence quality did not. Cross-examination did not increase juror sensitivity to evidence quality. Implications for science in the legal system are discussed.

Informal arguments take place when individuals exchange views on whether it is worthwhile to believe some assertion or take some action. Debates between friends or family members, classroom sparring about an idea, scientific exchanges about empirical results or theories, and critical discussions and responses in many fields can all be instances of arguments. This article describes the structure of these arguments in terms of the conversational moves that participants can make within them - for example, asking for a justification, giving a reason, offering an objection, or conceding a point. The central part of the article proposes a model for the way people determine to which of the argument's claims each participant is committed. According to the model, commitment is the result of rules defined over the sequence of conversational moves. A participant's commitment to claims that occur later in the argument has well-defined implications for commitment to claims that occurred earlier. Predictions from the model compare well with people's judgments of commitment over a range of argument types. The analysis of argument commitment also illuminates concepts such as burden of proof that are difficult to define within current reasoning theories that treat just a single side of an issue.

Research has demonstrated the various directive effects of attitudes on processing information. The manner in which existing attitudes affect the evaluation of new information through logical, deductive reasoning processes is investigated. Results are consistent with a growing body of evidence that the different dimensions of attitude strength have unique effects. A surprisingly constraining set of circumstances was required for people to rely on their existing attitudes when evaluating new issues.