Biomedical subjects

P N Johnson-Laird

Publications and source records attributed to P N Johnson-Laird.

At least 19 recordsLinked to original sources

PubMed2006

A hyper-emotion theory of psychological illnesses.

A hyper-emotion theory of psychological illnesses is presented. It postulates that these illnesses have an onset in which a cognitive evaluation initiates a sequence of unconscious transitions yielding a basic emotion. This emotion is appropriate for the situation but inappropriate in its intensity. Whenever it recurs, it leads individuals to a focus on the precipitating situation and to characteristic patterns of inference that can bolster the illness. Individuals with a propensity to psychological illness accordingly reason better than more robust individuals, but only on topics relevant to their illness. The theory is assessed in the light of previous research, a small epidemiological study of patients, and 3 empirical studies.

Affect↗

PubMed2006

Reasoning about the relations between relations.

Relations can hold between relations, as in assertions such as: Cordelia loves Lear more than Goneril does. Naïve reasoners can make inferences that depend on these higher order relations, which are vital for science and mathematics, but no existing theory explains such inferences. The present paper presents a theory based on mental models of the situations under description, and it reports four experiments corroborating the theory. Experiment 1a showed that the difficulty of such inferences from two premises depends on the integration of the information from the premises into a single model. The same result held in Experiment 1b, even when individuals were not permitted to make written workings. Experiment 2 required the participants to think aloud, and their protocols revealed that they developed three main strategies. Experiment 3 biased the development of these strategies, showing that individuals assemble them "bottom up" from various tactical steps.

Adult↗

PubMed2005

Naïve deontics: a theory of meaning, representation, and reasoning.

Deontic assertions concern what one ought to do, may do, and ought not to do. This paper proposes a theory of their meanings and of how these meanings are represented in mental models. The meanings of deontic assertions refer to sets of permissible and impermissible states. An experiment corroborated the ability of individuals to list these states. The most salient were those corresponding to the mental models of the assertions. When individuals reason, they rely on mental models, which do not make all states explicit. The theory predicts the most frequent conclusions drawn from deontic premises. It also predicts the occurrence of illusory inferences from assertions of permission, i.e., inferences that seem highly plausible but that are in fact invalid. Assertions of prohibitions, according to the theory, should reduce the illusions. Further experiments corroborated these predictions.

Humans↗

PubMed2005

Reasoning about relations.

Inferences about spatial, temporal, and other relations are ubiquitous. This article presents a novel model-based theory of such reasoning. The theory depends on 5 principles. (a) The structure of mental models is iconic as far as possible. (b) The logical consequences of relations emerge from models constructed from the meanings of the relations and from knowledge. (c) Individuals tend to construct only a single, typical model. (d) They spontaneously develop their own strategies for relational reasoning. (e) Regardless of strategy, the difficulty of an inference depends on the process of integration of the information from separate premises, the number of entities that have to be integrated to form a model, and the depth of the relation. The article describes computer implementations of the theory and presents experimental results corroborating its main principle.

Algorithms↗

PubMed2004

Reasoning from inconsistency to consistency.

This article presents a theory of how individuals reason from inconsistency to consistency. The theory is based on 3 main principles. First, individuals try to construct a single mental model of a possibility that satisfies a current set of propositions, and if the task is impossible, they infer that the set is inconsistent. Second, when an inconsistency arises from an incontrovertible fact, they retract any singularly dubious proposition or any proposition that is inconsistent with the fact; otherwise, they retract whichever proposition mismatches the fact. A mismatch can arise from a proposition that has only mental models that conflict with the fact or fail to represent it. Third, individuals use their causal knowledge-in the form of models of possibilities-to create explanations of what led to the inconsistency. A computer program implements the theory, and experimental results support each of its principles.

Computer Simulation↗

PubMed2004

Co-reference and reasoning.

Co-reference occurs when two or more noun phrases refer to the same individual, as in the following inferential problem: Mark is kneeling by the fire or he is looking at the TV but not both. / Mark is kneeling by the fire. / Is he looking at the TV? In three experiments, we compared co-referential reasoning problems with problems referring to different individuals. Experiment 1 showed that co-reference improves accuracy. In Experiment 2, we replicated that finding and showed that co-reference speeds up both reading and inference. Experiment 3 showed that the effects of co-reference are greatest when the premises and the conclusion share co-referents. These effects led the participants to make illusory inferences--that is, to draw systematically invalid conclusions. The results are discussed in terms of the mental model theory of reasoning.

Adolescent↗

PubMed2003

Reasoning, models, and images: behavioral measures and cortical activity.

The goal of this study was to investigate the neurocognitive processes of mental imagery in deductive reasoning. Behavioral studies yielded four sorts of verbal relations: (1) visuospatial relations that are easy to envisage both 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. In three experiments, visual relations slowed the process of reasoning in comparison with control relations, whereas visuospatial and spatial relations yielded inferences comparable to those of control relations. An experiment using functional magnetic resonance imaging showed that in the absence of any correlated visual input (problems were presented acoustically via headphones), all types of reasoning problems evoked activity in the left middle temporal gyrus, in the right superior parietal cortex, and bilaterally in the precuneus. In the prefrontal cortex, increased activity was found in the middle and inferior frontal gyri. However, only the problems based on visual relations also activated areas of the visual association cortex corresponding to V2. The results indicate that cortical activity during reasoning depends on the nature of verbal relations. All relations elicit mental models that underlie reasoning, but visual relations in addition elicit visual images. This account resolves inconsistencies in the previous literature.

Acoustic Stimulation↗

PubMed2003

Models of consistency.

This article presents a theory of how individuals detect whether descriptions of an entity are consistent or inconsistent. The theory postulates that individuals try to construct a mental model of the entity in which all the propositions are true. If they succeed, they infer that the description is consistent; otherwise, they infer that it is inconsistent. We report three experiments that corroborated the theory. Experiment 1 confirmed that evaluating consistency is easier when an initial model suffices than when reasoners have to find an alternative model. Experiment 2 established the occurrence of illusion, inferences about the properties of entities. Experiment 3 showed that the illusions correspond to mental models of the assertions, even when these models are wrong because they fail to represent what is false.

Adolescent↗

PubMed2003

Counterexamples in sentential reasoning.

How do logically naive individuals determine that an inference is invalid? In logic, there are two ways to proceed: (1) make an exhaustive search but fail to find a proof of the conclusion and (2) use the interpretation of the relevant sentences to construct a counterexample--that is, a possibility consistent with the premises but inconsistent with the conclusion. We report three experiments in which the strategies that individuals use to refute invalid inferences based on sentential connectives were examined. In Experiment 1, the participants' task was to justify their evaluations, and it showed that they used counterexamples more often than any other strategy. Experiment 2 showed that they were more likely to use counterexamples to refute invalid conclusions consistent with the premises than to refute invalid conclusions inconsistent with the premises. In Experiment 3, no reliable difference was detected in the results between participants who wrote justifications and participants who did not.

Concept Formation↗

PubMed2002

Conditionals: a theory of meaning, pragmatics, and inference.

The authors outline a theory of conditionals of the form If A then C and If A then possibly C. The 2 sorts of conditional have separate core meanings that refer to sets of possibilities. Knowledge, pragmatics, and semantics can modulate these meanings. Modulation can add information about temporal and other relations between antecedent and consequent. It can also prevent the construction of possibilities to yield 10 distinct sets of possibilities to which conditionals can refer. The mental representation of a conditional normally makes explicit only the possibilities in which its antecedent is true, yielding other possibilities implicitly. Reasoners tend to focus on the explicit possibilities. The theory predicts the major phenomena of understanding and reasoning with conditionals.

Humans↗

PubMed2002

Visual imagery can impede reasoning.

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.

Adult↗

PubMed2001

Are conjunctive inferences easier than disjunctive inferences? A comparison of rules and models.

We report four experiments investigating conjunctive inferences (from a conjunction and two conditional premises) and disjunctive inferences (from a disjunction and the same two conditionals). The mental model theory predicts that the conjunctive inferences, which require one model, should be easier than the disjunctive inferences, which require multiple models. Formal rule theories predict either the opposite result or no difference between the inferences. The experiments showed that the inferences were equally easy when the participants evaluated given conclusions, but that the conjunctive inferences were easier than the disjunctive inferences (1) when the participants drew their own conclusions, (2) when the conjunction and disjunction came last in the premises, (3) in the time the participants spent reading the premises and in responding to given conclusions, and (4) in their ratings of the difficulty of the inferences. The results support the model theory and demonstrate the importance of reasoners' inferential strategies.

Cognition↗

PubMed2001

Mental models and logical reasoning problems in the GRE.

The Graduate Record Examination (GRE) contains a class of complex reasoning tests known as logical reasoning problems. These problems are demanding for human reasoners and beyond the competence of any existing computer program. This article applies the mental model theory of reasoning to the analysis of these problems. It predicts 3 main causes of difficulty, which were corroborated by the results of 4 experiments: the nature of the logical task (Experiment 1), the set of foils (Experiment 2), and the nature of the conclusions (Experiments 3 and 4). This article shows how these factors can be applied to the design of new problems.

Educational Measurement↗

PubMed2000

Illusions in reasoning about consistency.

Reasoners succumb to predictable illusions in evaluating whether sets of assertions are consistent. We report two studies of this computationally intractable task of "satisfiability." The results show that as the number of possibilities compatible with the assertions increases, the difficulty of the task increases, and that reasoners represent what is true according to assertions, not what is false. This procedure avoids overloading memory, but it yields illusions of consistency and of inconsistency. These illusions modify our picture of human rationality.

Adult↗

PubMed2000

Illusions in quantified reasoning: how to make the impossible seem possible, and vice versa.

The mental model theory postulates that reasoners build models of the situations described in premises, and that these models normally represent only what is true. The theory has an unexpected consequence. It predicts the existence of illusions in inferences. Certain inferences should have compelling but erroneous conclusions. Two experiments corroborated the occurrence of such illusions in inferences about what is possible from disjunctions of quantified assertions, such as, "at least some of the plastic beads are not red." Experiment 1 showed that participants erroneously inferred that impossible situations were possible, and that possible situations were impossible, but that they performed well with control problems based on the same premises. Experiment 2 corroborated these findings in inferences from assertions based on dyadic relations, such as, "all the boys played with the girls."

Adult↗

PubMed2000

How to eliminate illusions in quantified reasoning.

The mental model theory postulates that reasoners build models of situations described in premises. These models normally make explicit only what is true according to the premises. The theory has an unexpected consequence. It predicts the existence of illusions in inferences: Certain inferences should have compelling but erroneous conclusions. Previous studies have corroborated the existence of such illusions. The present study reports the first effective antidote to them. For example, most people incorrectly answer "yes" to the following problem: Only one of the following statements is true ... /At least some of the plastic beads are not red./None of the plastic beads are red./Is it possible that none of the red beads are plastic? In two experiments, we progressively eliminated this fallacy and others by using instructions designed to overcome the bias toward truth. The difference between the illusory and the control problems disappeared when the participants were instructed to work out both the case in which the first premise was true and second premise was false and the case in which the second premise was true and the first premise was false.

Attention↗

PubMed2000

Illusions in modal reasoning.

According to the mental model theory, models represent what is true, but not what is false. One unexpected consequence is that certain inferences should have compelling, but invalid, conclusions. Three experiments corroborated the occurrence of such illusions in reasoning about possibilities. When problems had the heading "Only one of the premises is true," the participants considered the truth of each premise in turn, but neglected the fact that when one premise is true, the others are false. When two-premise problems had the heading "One of the premises is true and one is false," the participants still neglected the falsity of one of the premises. As predicted, however, the illusions were reduced when reasoners were told to check their conclusions against the constraint that only one of the premises was true. We discuss alternative explanations for illusory inferences and their implications for current theories of reasoning.

Cognition↗

PubMed1999

Illusory inferences: a novel class of erroneous deductions.

The mental model theory postulates that reasoners build models of the situations described in premises, and that these models normally make explicit only what is true. The theory has an unexpected consequence: it predicts the occurrence of inferences that are compelling but invalid. They should arise from reasoners failing to take into account what is false. Three experiments corroborated the systematic occurrence of these illusory inferences, and eliminated a number of alternative explanations for them. Their results illuminate the controversy among various current theories of reasoning.

Adult↗