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Valerie A Thompson

Publications and source records attributed to Valerie A Thompson.

8 recordsLinked to original sources
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↗
PubMed2006

Confidence and accuracy in deductive reasoning.

In two experiments, we investigated the relationship between confidence and accuracy in syllogistic reasoning. Participants judged the validity of conclusions and provided confidence ratings twice for each problem: once quickly and again after further deliberation. Correlations between confidence and accuracy were small or nonexistent. In addition, confidence and accuracy were mediated by different variables. Confidence judgments appeared to reflect external cues, so that confidence was greater when the participants were allowed additional time to think about the problem, as well as when the conclusion was either believable or unbelievable, rather than neutral. In contrast, accuracy changed little as a function of the amount of time available and did not differ for believable and neutral problems. These data support a model in which initial decisions are made quickly, on the basis of heuristic cues, and analytic processes are used to justify or rationalize the earlier decision.

Adult↗
PubMed2003

A dual-process model of belief and evidence interactions in causal reasoning.

In three experiments, we examined how reasoners' preexisting beliefs about causal relations constrained their evaluation of covariation-based empirical evidence. Reasoners were presented with causal candidates that were a priori rated to be either believable or unbelievable, as well as information regarding the degree to which the cause and the effect covaried. Several findings supported the conclusion that preexisting beliefs about causal relations reflect knowledge of both causal mechanisms and covariation relations, that these sources of knowledge are represented independently and contribute independently to causal judgments, and that the evaluation of new empirical evidence is influenced differently by mechanism-based and covariation-based beliefs. Finally, we observed that reasoners were relatively accurate in evaluating the degree to which their judgments were sensitive to empirical evidence but were less able to judge how much their judgments were influenced by their prior beliefs. We present a dual-process model that provides a descriptive account of the boundary conditions for belief and evidence interactions in causal reasoning.

Adolescent↗
PubMed2003

Syllogistic reasoning time: disconfirmation disconfirmed.

Models of deductive reasoning typically assume that reasoners dedicate more logical analysis to unbelievable conclusions than to believable ones (e.g., Evans, Newstead, Allen, & Pollard, 1994; Newstead, Pollard, Evans, & Allen, 1992). When the conclusion is believable, reasoners are assumed to accept it without much further thought, but when it is unbelievable, they are assumed to analyze the conclusion, presumably in an attempt to disconfirm it. This disconfirmation hypothesis leads to two predictions, which were tested in the present experiment: Reasoners should take longer to reason about problems leading to unbelievable conclusions, and reasoners should consider more models or representations of premise information for unbelievable conclusions than for believable ones. Neither prediction was supported by our data. Indeed, we observed that reasoners took significantly longer to reason about believable conclusions than about unbelievable ones and generated the same number of representations regardless of the believability of the premises. We propose a model, based on a modified version of verbal reasoning theory (Polk & Newell, 1995), that does not depend on the disconfirmation assumption.

Adolescent↗
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

More power to you: simple power calculations for treatment effects with one degree of freedom.

Although numerous computer programs for statistical power analysis are available, power is an under-used aspect of experimental analysis, perhaps because of the perceived difficulty of performing the necessary calculations or because existing computer software can be expensive or complicated to learn. For single-degree-of-freedom tests, however, it is possible to calculate power in a straightforward manner, using the t distribution. Because these calculations are based on t, they use easily understood and readily available quantities. These calculations can be performed with a desk calculator; we also present a simple-to-use program called MorePower that will perform the necessary calculations. The straightforward nature of the calculations potentially will enable more researchers to consider issues of power when planning and reporting their experiments.

Humans↗
PubMed2002

Reasoning counterfactually: making inferences about things that didn't happen.

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., approximately q therefore approximately p). These findings occurred with familiar and unfamiliar content, affirmative and negative conditionals, and conditional and biconditional relations.

Adolescent↗