Biomedical subjects

L J Rips

Publications and source records attributed to L J Rips.

7 recordsLinked to original sources

PubMed1990

Paralogical reasoning: Evans, Johnson-Laird, and Byrne on liar and truth-teller puzzles.

People's performance on knight/knave problems is deliberate. They make assumptions, draw deductive inferences from them, and evaluate the consequences of these inferences. In an initial paper on this topic (Rips, 1989), I proposed a model for a subset of such problems that depend on sentential reasoning. The main component of the model is a set of natural-deduction rules, drawn from prior work on propositional inference. This natural-deduction framework seems well suited to explain the reasoning that subjects display on these problems, since it incorporates a mechanism for making assumptions and following them up. Moreover, the number of assumptions and rule applications needed to solve a problem yields an intuitively appealing measure of how difficult the problem should be. In accord with this prediction, the experiments found increases in error rates and reaction times as a function of the assumptions-plus-inferences measure. In their note, Johnson-Laird and Byrne sketch a possible alternative. Their account posits five processing strategies tailored to this problem domain and a mechanism for evaluating sentential arguments based on mental models. The mental-model component is a variation on the usual truth-table method, where individual models correspond to truth-table rows. The main prediction of this component is that the more models subjects must consider, the harder the problem. However, the experiment reported here found no evidence for this prediction. Problems with larger numbers of models do not yield higher error rates than those with few. What does cause difficulties for subjects is scope relations among connectives, a fact that inference-rule theories can easily explain. Given these findings, it's not surprising that the predictive burden for knight/knave problems must be carried by Johnson-Laird and Byrne's strategies, rather than by mental models. These strategies control the order in which subjects consider parts of the problem, and they provide possible stopping points. There are, however, several difficulties with these strategies. Of their four new strategies, Johnson-Laird and Byrne offer no evidence at all for two of them. Of the remaining two, only one accounts for a significant proportion of the variance when allowance is made for confounding variables. Moreover, all four strategies are ad hoc, rather than being derived from some more general theory. Certainly, much remains to be done in filling out the picture of how such problems are handled, as both Evans and Johnson-Laird and Byrne point out.(ABSTRACT TRUNCATED AT 400 WORDS)

Concept Formation↗

PubMed1990

Parts of activities: reply to Fellbaum and Miller (1990).

If people believe that one activity is a kind of another, they also tend to believe that the second activity is a part of the first. For example, they assert that deciding is a kind of thinking and that thinking is a part of deciding. Fellbaum and Miller's (1990) explanation for this phenomenon is based on the idea that people interpret part of in the domain of verbs as a type of logical entailment. Their explanation, however, suffers from at least 2 deficiencies. First, it fails to account for parallel effects with nouns (e.g., a contest is a kind of an activity, and an activity is a part of a contest). Second, it contains a flaw that incorrectly predicts many activities to be parts of each other (e.g., coming is part of going and going part of coming). However, a hypothesis Rips and Conrad (1989) originally proposed for the kind-part reciprocal effect avoids both of these difficulties.

Behavior↗

PubMed1990

Reasoning.

Strict theories of reasoning are schoolmarmish in their insistence on rules and structure, but this gives them an advantage when inference is relatively well behaved. In the case of reasoning with deductively valid arguments, Strict theories give a convincing account of the universality of certain inference forms and the productivity of reasoning in comprehension and production. However, Strict views are rather frail, since they have to appeal to nonreasoning processes (memory limitations, comprehension failure, conversational factors) when inferencing breaks down. They seem less suited to inductive and analogical arguments, though they may be helpful in restricted situations where the inference is routine or the domain well understood. By contrast, Loose theories are inarticulate and nerdy. They dispense with formal rules in favor of continuous functions defined over beliefs, and the inferences they describe are modulations of these functions. In some sense, they are more robust than Strict theories, since they apply not only to inductively strong arguments but also to deductively valid ones as a limiting case. In fact, we have seen that they can provide insight into subjects' responses to purportedly deductive problems that are too unruly for Strict theories to handle. They are also extremely literal-minded in refusing to recognize permanent generalizations. Their only generalities are temporary products of their updating schemes. Because of these features, Loose theories have trouble producing new beliefs, explaining or justifying their own inferences, and keeping straight the difference between correlational and causal evidence. As I've described them here, Strict and Loose views are postures, not scientific theories. It's hard to see how either point of view could be exclusively true, but equally hard to combine their insights successfully.

Cognition↗

PubMed1989

The psychology of knights and knaves.

Knight-knave brain teasers are about a realm in which some people, knights, tell only truths, whereas all others, knaves, tell only lies. For example, suppose person A says, "I am a knight and B is a knight," and person B says, "A is a knave." Is A a knight or a knave? Is B a knight or a knave? In a pilot study, we asked subjects to think aloud while solving problems like these. Their statements suggested that they were making assumptions about the knight/knave status of the characters and drawing deductive inferences from these assumptions to test their consistency. This encouraged us to model the process by means of a simulation based on an earlier natural-deduction theory of reasoning. The model contains a set of deduction rules in the form of productions and a working memory that holds a proof of the correct answer. The greater the number of steps (assumptions and inferences) in the proof, the greater the predicted difficulty of the puzzle. The experiments reported here confirmed this prediction by showing that subjects were more likely to make mistakes (Experiment 1) and take longer to solve (Experiment 2) puzzles associated with a larger number of proof steps.

Computer Simulation↗

PubMed1989

Folk psychology of mental activities.

A central aspect of people's beliefs about the mind is that mental activities--for example, thinking, reasoning, and problem solving-- are interrelated, with some activities being kinds or parts of others. In common-sense psychology, reasoning is a kind of thinking and reasoning is part of problem solving. People's conceptions of these mental kinds and parts can furnish clues to the ordinary meaning of these terms and to the differences between folk and scientific psychology. In this article, we use a new technique for deriving partial orders to analyze subjects' decisions about whether one mental activity is a kind or part of another. The resulting taxonomies and partonomies differ from those of common object categories in exhibiting a converse relation in this domain: One mental activity is a part of another if the second is a kind of the first. The derived taxonomies and partonomies also allow us to predict results from further experiments that examine subjects' memory for these activities, their ratings of the activities' importance, and their judgements about whether there could be "possible minds" that possess some of the activities but not others.

Cognition↗

PubMed1987

Answering autobiographical questions: the impact of memory and inference on surveys.

Survey questions often probe respondents for quantitative facts about events in their past: "During the last 2 weeks, on days when you drank liquor, about how many drinks did you have?" "During the past 12 months, how many visits did you make to a dentist?" "When did you last work at a full-time job?" are all examples from national surveys. Although questions like these make an implicit demand to remember and enumerate specific autobiographical episodes, respondents frequently have trouble complying because of limits on their ability to recall. In these situations, respondents resort to inferences that use partial information from memory to construct a numeric answer. Results from cognitive psychology can be useful in understanding and investigating these phenomena. In particular, cognitive research can help in identifying situations that inhibit or facilitate recall and can reveal inferences that affect the accuracy of respondents' answers.

Cognition↗

PubMed1982

Order information in multiple-element comparison.

Although it is possible to specify the elements of a list without regard to the order in which they appear, the same distinction may not be possible when the elements are retrieved from memory. To investigate this issue, we used a recognition task in which two strings of letters are presented sequentially. Subjects were instructed to respond "Same" if the second string contained the same elements as the first, regardless of their position, and to respond "Different" otherwise. Despite the fact that order information is irrelevant in this task, we observed in two experiments that reaction time for Same-item trials increased with the number of positions that the letters were displaced. Neither familiarity of the first string nor the delay between strings changed in the size of this displacement effect. To account for this finding, we propose a model in which comparison time for a given letter pair increases with the position difference of the elements in their respective strings.

Discrimination Learning↗