Biomedical subjects

W Schaeken

Publications and source records attributed to W Schaeken.

4 recordsLinked to original sources

PubMed2000

The effect of explicit negatives and of different contrast classes on conditional syllogisms.

One experiment tested the effects of systematically negating the constituents of four fundamental inferences based on conditionals: Modus Ponens (i.e. inferences of the form: if p then q; p therefore q), Modus Tollens (if p then q; not-q therefore not-p); Affirmation of the Consequent (if p then q; q therefore p), and Denial of the Antecedent (if p then q; not-p therefore not-q). The latter two inferences are valid only for bi-conditionals (if, and only if, p then q). The participants drew their own conclusions from premises about letters and numbers on cards. We observed a significant effect of explicit negatives on Modus Tollens and Denial of the Antecedent problems: The inferences were drawn more often for conditionals that yield a negative conclusion (e.g. if p then not q; q therefore not p) than for conditionals that yield an affirmative conclusion (e.g. if not p then q; not q therefore p). Additionally, we observed a similar, but smaller effect on Affirmation of the Consequent problems. Furthermore, we observed a significant effect of the categorical premise (affirmative or negative), especially on Affirmation of the Consequent problems. Finally, we observed an effect of the magnitude of the contrast class. If the contrast is larger (a set of three, five or nine values), then the making of a double negation or the production of an affirmative conclusion is more difficult for Denial of the Antecedent inferences. We discussed the results in relation to a negative categorical premise bias, an affirmative premise bias, a negative conclusion bias and a double negation effect.

Adult↗

PubMed1996

Must reasoning.

The mental model theory of reasoning postulates that individuals reason by constructing models of the situations described by the premises, but the number of explicit models and the information in them is kept to a minimum. The initial models of modal conditionals don't only represent the situations, but they also comment these situations, in terms of permissible and impermissible. The present paper reports three experiments which test the prediction of the mental model theory that a modus tollens inference is easier with a rule that contains the auxiliary verb 'must'. Unlike a normal rule, there is no need to flesh out the models explicitly with a rule containing 'must'. Overall, the results corroborate the prediction of the mental model theory.

Cognition↗

PubMed1996

Mental models and temporal reasoning.

We report five experiments investigating reasoning based on temporal relations, such as: "John takes a shower before he drinks coffee". How individuals make temporal inferences has not been studied hitherto, but we conjectured that they construct mental models of events, and we developed a computer program that reasons in this way. As the program shows, a problem of the form: a before b b before c d while b e while c What is the relation between d and e? where a, b, c, etc. refer to everyday events, calls for just one model, whereas a problem in which the second premise is modified to c before b calls for multiple models because a may occur before c, after c, or at the same time as c. Experiments 1-3 showed that problems requiring one mental model elicited more correct responses than problems requiring multiple models, which in turn elicited more correct answers than multiple model problems with no valid answers. Experiment 4 contrasted the predictions of the model theory with those based on formal rules of inference; its results corroborated the model theory. Experiment 5 confirmed that a premise leading to multiple models took longer to read than the corresponding premise in one-model problems, and that latency to respond correctly was greater for multiple-model problems than for one-model problems. We conclude that the experiments corroborate the mental model theory.

Adolescent↗

PubMed1992

Propositional reasoning by model.

This article describes a new theory of propositional reasoning, that is, deductions depending on if, or, and, and not. The theory proposes that reasoning is a semantic process based on mental models. It assumes that people are able to maintain models of only a limited number of alternative states of affairs, and they accordingly use models representing as much information as possible in an implicit way. They represent a disjunctive proposition, such as "There is a circle or there is a triangle," by imagining initially 2 alternative possibilities: one in which there is a circle and the other in which there is a triangle. This representation can, if necessary, be fleshed out to yield an explicit representation of an exclusive or an inclusive disjunction. The theory elucidates all the robust phenomena of propositional reasoning. It also makes several novel predictions, which were corroborated by the results of 4 experiments.

Algorithms↗