Immediate inferences from quantified assertions

How quantifiers influence the conceptual representation of plurals

This paper reports the results of two experiments that investigate the nature of plural conceptual representations that are created during sentence comprehension. Previous work has found that comprehenders seem to represent both a singular object and a plural set of objects during the comprehension of plural nouns. The activation of the singular object has been attributed to the pragmatic processing involved in understanding the plural (Patson, Journal of Experimental Psychology: Learning, Memory and Cognition, 42, 1140-1153, 2016a). The goal of the current study was to further investigate this hypothesis. Experiment 1 used a picture-matching paradigm to investigate how comprehenders conceptualize plural nouns quantified with many, which renders the scalar implicature unnecessary. Consistent with the pragmatic processing hypothesis, comprehenders did not activate a singular form when the plural was quantified with many. Experiment 2 was designed to further investigate whether all quantifiers block activation of the singular form. The same picture-matching paradigm was used with numerical quantifiers that specify numbers either within or above the subitization range. When the number was within the subitization range, comprehenders' conceptual representations contained exactly that number of objects, and importantly did not contain a singular object. When number was above the subitization range, comprehenders' conceptual representations did not contain an exact number of objects and seemed to activate a singular object. These data are consistent with constraints on how many objects can be represented in visual working memory. Taken together, the results of these two experiments suggest that the plural's conceptual representation emerged as a result of grammatical processing as well as limits on the visual processing system.

Explanatory completeness

All explanations are incomplete, but reasoners think some explanations are more complete than others. To explain this behavior, we propose a novel theory of how people assess explanatory incompleteness. The account assumes that reasoners represent explanations as causal mental models - iconic representations of possible arrangements of causes and effects. A complete explanation refers to a single integrated model, whereas an incomplete explanation refers to multiple models. The theory predicts that if there exists an unspecified causal relation - a gap - anywhere within an explanation, reasoners must maintain multiple models to handle the gap. They should treat such explanations as less complete than those without a gap. Four experiments provided participants with causal descriptions, some of which yield one explanatory model, e.g., A causes B and B causes C, and some of which demand multiple models, e.g., A causes X and B causes C. Participants across the studies preferred one-model descriptions to multiple-model ones on tasks that implicitly and explicitly required them to assess explanatory completeness. The studies corroborate the theory. They are the first to reveal the mental processes that underlie the assessment of explanatory completeness. We conclude by reviewing the theory in light of extant accounts of causal reasoning.

Reasoning about Durations

A set of assertions is consistent provided they can all be true at the same time. Naive individuals could prove consistency using the formal rules of a logical calculus, but it calls for them to fail to prove the negation of one assertion from the remainder in the set. An alternative procedure is for them to use an intuitive system (System 1) to construct a mental model of all the assertions. The task should be easy in this case. However, some sets of consistent assertions have no intuitive models and call for a deliberative system (System 2) to construct an alternative model. Formal rules and mental models therefore make different predictions. We report three experiments that tested their respective merits. The participants assessed the consistency of temporal descriptions based on statements using "during" and "before." They were more accurate for consistent problems with intuitive models than for those that called for deliberative models. There was no robust difference in accuracy between consistent and inconsistent problems. The results therefore corroborated the model theory.

Possibilities as the foundation of reasoning

Reasoning about possibilities is fundamental in daily life. Yet, it has been little studied in psychology. We present a psychological theory in which it is the foundation of human reasoning. The theory explains how possibilities have distinct interpretations (deontic, epistemic, and alethic), how people represent them in models, and how these models yield inferences. Key principles are that the semantics of possibilities are the same finitary alternatives underlying probabilities, that speech acts can create obligations inexpressible as probabilities, that compound assertions - conditionals and disjunctions - refer to conjunctions of possibilities holding in default of knowledge to the contrary, and that mental models condense multiple consistent possibilities into one. The theory is incompatible with all normal modal logics and with probabilistic logic. Yet, experiments have corroborated its predictions. The article discusses its precursors, rivals, and potentials.

Reasoning strategy modulates gender differences in performance on a spatial rotation task

The dual-strategy model of reasoning has proposed that individual differences in reasoning can be understood as due to two general ways of processing information: an analytic, counterexample strategy that examines information for explicit potential counterexamples and an intuitive, statistical strategy that uses associative access to generate a likelihood estimate of putative conclusions. Previous studies have examined this model in the context of basic conditional reasoning tasks. However, the distinctions that underlie the dual-strategy model can be seen as a basic description of more general differences in information processing. A recent study examining interactions between gender and strategy use in processing of negative emotions found that gender differences were modulated by strategy, with the general advantage of females concentrated within statistical reasoners. Two studies were performed to extend this analysis to performance on a mental rotation task for which there also exist clear gender differences. The initial study presented rotation tasks with unlimited time. Results show that males perform better on more difficult rotation tasks than females, with the difference concentrated among statistical reasoners. The second study replicated this using a restricted time (4 s) to make each judgement and showed an increase in the effect of both gender and strategy. This provides additional evidence that the dual-strategy model captures an important individual difference in the general way that information is processed.

Probabilistic representation in syllogistic reasoning: A theory to integrate mental models and heuristics

This paper presents a new theory of syllogistic reasoning. The proposed model assumes there are probabilistic representations of given signature situations. Instead of conducting an exhaustive search, the model constructs an individual-based "logical" mental representation that expresses the most probable state of affairs, and derives a necessary conclusion that is not inconsistent with the model using heuristics based on informativeness. The model is a unification of previous influential models. Its descriptive validity has been evaluated against existing empirical data and two new experiments, and by qualitative analyses based on previous empirical findings, all of which supported the theory. The model's behavior is also consistent with findings in other areas, including working memory capacity. The results indicate that people assume the probabilities of all target events mentioned in a syllogism to be almost equal, which suggests links between syllogistic reasoning and other areas of cognition.

The probabilities of unique events

Many theorists argue that the probabilities of unique events, even real possibilities such as President Obama's re-election, are meaningless. As a consequence, psychologists have seldom investigated them. We propose a new theory (implemented in a computer program) in which such estimates depend on an intuitive non-numerical system capable only of simple procedures, and a deliberative system that maps intuitions into numbers. The theory predicts that estimates of the probabilities of conjunctions should often tend to split the difference between the probabilities of the two conjuncts. We report two experiments showing that individuals commit such violations of the probability calculus, and corroborating other predictions of the theory, e.g., individuals err in the same way even when they make non-numerical verbal estimates, such as that an event is highly improbable.