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PubMed1997

Probabilistic reasoning in deluded, depressed and normal subjects: effects of task difficulty and meaningful versus non-meaningful material.

BACKGROUND: Research indicates that deluded patients 'jump to conclusions' on probabilistic reasoning tasks. Two experiments were carried out with patients suffering from persecutory delusions and depressed and normal controls in order to determine whether this response bias is affected by task difficulty and the meaningfulness of the materials. METHODS: Tasks were variants of those employed by Huq et al. (1988) and Garety et al. (1991). In Experiment 1, subjects judged which of two bags a sequence of coloured beads had been taken from. Difficulty was manipulated by varying the ratios of coloured beads in the bags. In experiment 2, a neutral condition required judgements about coloured beads drawn whereas, in meaningful conditions, subjects had to judge whether personality characteristics described one of two individuals. RESULTS: In Experiment 1, estimates of certainty varied with task difficulty, and there was no evidence of 'jumping to conclusions' in the deluded group. In Experiment 2, all groups reached an initial level of certainty and reduced their estimates of certainty following disconfirmatory evidence more quickly in the meaningful conditions. Both clinical groups expressed higher certainty levels in early trials, and a greater magnitude of reduction in certainty following disconfirmatory information. These group differences were more evident in the meaningful conditions than in the neutral conditions. CONCLUSIONS: Probabilistic reasoning is affected by task difficulty and meaningfulness of materials in both deluded and depressed subjects. Observed reasoning abnormalities were not specific to the deluded group.

Adult↗
PubMed1999

The importance of pragmatic aspects in conditional reasoning.

The importance of pragmatic aspects in conditional reasoning was assessed in the performance of 54 subjects (26 female and 28 male; mean age 17.6 years) on 48 conditional inference problems, using a 3 x 2 x 4 design, with repeated measurements. The independent variables were probability of empirical frequency in the real world, type of conditional rule, and scenario availability. Number of correct responses and subjects' certainty about the correctness of their responses were the dependent variables. The results showed: a) the scenario availability is not sufficient in itself to explain differences in performance, but it does affect the subjects' degree of confidence in their conclusions; b) there is an interaction between probability of empirical frequency in the real world and type of conditional rule on correct performance. The results were contrasted with the predictions made by the mental models theory and its revised version proposed by Evans (1993). These findings support the semantic theories of conditional reasoning.

Adolescent↗
PubMed2002

Random number generation in autism.

This study explored the ability of individuals with autism to generate a unique series of digits. Fourteen low-functioning individuals with autism, 14 intellectually disabled individuals, and 14 postgraduate university students generated a series of pseudo-random digits. Individuals with autism were more likely to repeat previous digits than were either of the control groups. The normal control group, however, was less likely to attempt cycling through all digits before repeating. Accordingly, low-functioning individuals with autism may exhibit a short-fall in response inhibition. This finding supports the executive dysfunction theory of autism.

Adolescent↗
PubMed2002

The malleability of anchoring effects.

Anchoring effects--the assimilation of a numeric estimate to a previously considered standard--are typically described as very robust and persistent. Based on the assumption that judgmental anchoring involves a hypothesis-testing process in which judges actively seek and generate judgment-relevant target knowledge, it was assumed that anchoring effects might at the same time be fairly malleable. Specifically, subtle influences that change the nature of the tested hypothesis are likely to affect the magnitude of anchoring. Using a procedural priming task, judges were induced to focus on similarities versus differences during a series of anchoring tasks. The results demonstrate that the magnitude of the obtained effect critically depended on this manipulation. In particular, a more pronounced anchoring assimilation effect resulted for judges with a similarity rather than a difference focus. Implications of these findings for models of anchoring as well as for the nature of the anchoring phenomenon are discussed.

Adult↗
PubMed1992

The science of choosing the right decision threshold in high-stakes diagnostics.

Many diagnostic tasks require that a threshold be set to convert evidence that is a matter of degree into a positive or negative decision. Although techniques of decision analysis used in psychology help one select the particular threshold that is appropriate to a given situation and purpose, just the concept of adjusting the threshold to the situation is not appreciated in many important practical arenas. Testing for the human immunodeficiency virus (HIV) and for dangerous flaws in aircraft structures are used here as illustrations. This article briefly reviews the relevant techniques and develops those two examples with data. It suggests that use of the decision techniques could substantially benefit individuals and society and asks how that use might be facilitated.

Aircraft↗
PubMed1998

Young children's predictions of illness: failure to recognize probabilistic causation.

In this study preschool-age children made predictions for a set of salient probabilistic causes. Of interest was whether the children viewed outcomes of familiar causes of illness as definite or as probabilistic. In Experiment 1, children judged that a common cause would affect all members of a group in the same way. In Experiment 2, children believed they could definitely predict illness outcomes in a single case. These judgments contrasted with adults' variable and uncertain predictions. Children did recognize uncertainty in outcomes dependent on voluntary choices. Experiment 3 presented both high- and low-potency causes of illness. Children treated all causes of illness as nonprobabilistic. These results are discussed in the context of children's understanding of causal relations and the sources of variability.

Adult↗
PubMed1999

Comparison of the development of formal thought in adolescent cohorts aged 10 to 15 years (1967-1996 and 1972-1993).

Five standard Piagetian tests were administered to 180 adolescents between the ages of 10 and 15 years. The results were compared with those obtained in 1967 and in 1972 for similar participant samples. At equal ages, today's adolescents exhibited a higher level of cognitive development than the adolescents of 20 or 30 years ago. The amount of gain observed varied across tasks, being very large for combinatory thought but mixed for conservation. This acceleration of cognitive development can partially explain the continuous rise in intelligence test performance (Flynn effect).

Adolescent↗
PubMed1996

Covariation bias in panic-prone individuals.

Covariation estimates between fear-relevant (FR; emergency situations) or fear-irrelevant (FI; mushrooms and nudes) stimuli and an aversive outcome (electrical shock) were examined in 10 high-fear (panic-prone) and 10 low-fear respondents. When the relation between slide category and outcome was random (illusory correlation), only high-fear participants markedly overestimated the contingency between FR slides and shocks. However, when there was a high contingency of shocks following FR stimuli (83%) and a low contingency of shocks following FI stimuli (17%), the group difference vanished. Reversal of contingencies back to random induced a covariation bias for FR slides in high- and low-fear respondents. Results indicate that panic-prone respondents show a covariation bias for FR stimuli and that the experience of a high contingency between FR slides and aversive outcomes may foster such a covariation bias even in low-fear respondents.

Adult↗
PubMed1990

A probabilistic contrast model of causal induction.

Deviations from the predictions of covariational models of causal attribution have often been reported in the literature. These include a bias against using consensus information, a bias toward attributing effects to a person, and a tendency to make a variety of unpredicted conjunctive attributions. It is contended that these deviations, rather than representing irrational biases, could be due to (a) unspecified information over which causal inferences are computed and (b) the questionable normativeness of the models against which these deviations have been measured. A probabilistic extension of Kelley's analysis-of-variance analogy is proposed. An experiment was performed to assess the above biases and evaluate the proposed model against competing ones. The results indicate that the inference process is unbiased.

Adult↗
PubMed1990

The overconfidence effect in social prediction.

In five studies with overlapping designs and intents, subjects predicted a specific peer's responses to a variety of stimulus situations, each of which offered a pair of mutually exclusive and exhaustive response alternatives. Each prediction was accompanied by a subjective probability estimate reflecting the subjects' confidence in its accuracy--a measure validated in Study 5 by having subjects choose whether to "gamble" on the accuracy of their prediction or on the outcome of a simple aleatory event. Our primary finding was that in social prediction, as in other judgmental domains, subjects consistently proved to be highly overconfident. That is, regardless of the type of prediction item (e.g., responses to hypothetical dilemmas, responses to contrived laboratory situations, or self-reports of everyday behaviors) and regardless of the type of information available about the person whose responses they were predicting (e.g., predictions about roommates or predictions based on prior interviews), the levels of accuracy subjects achieved fell considerably below the levels required to justify their confidence levels. Further analysis revealed two specific sources of overconfidence. First, subjects generally were overconfident to the extent they were highly confident. Second, subjects were most likely to be overconfident when they knowingly or unknowingly made predictions that ran counter to the relevant response base rates and, as a consequence, achieved low accuracy rates that their confidence estimates failed to anticipate. Theoretical and normative implications are discussed and proposals for subsequent research offered.

Adult↗
PubMed1992

Does memory affect judgment? Self-generated versus recall memory measures.

Most evidence regarding the independence of memory and judgment comes from studies that used memory measures consisting of Ss' recall of raw input data (recall measures). Such evidence provides the primary support for on-line judgment formation. The results of 2 experiments suggest that self-generated memory measures capture the contents of memory at the time of judgement more effectively than recall measures and, accordingly, are more likely to provide evidence that memory and judgment are related. When directly compared, a self-generated measure provided evidence of a memory-judgment relationship and a recall measure did not. Thus, memory-based judgment formation may be more prevalent than the on-line processing literature suggests.

Adult↗
PubMed1994

Conflict between intuitive and rational processing: when people behave against their better judgment.

When offered an opportunity to win $1 on every "win" trial in which they drew a red jelly bean, subjects frequently elected to draw from a bowl that contained a greater absolute number, but a smaller proportion, of red beans (e.g., 7 in 100) than from a bowl with fewer red beans but better odds (e.g., 1 in 10). Subjects reported that although they knew the probabilities were against them, they felt they had a better chance when there were more red beans. Similar, but less extreme results were obtained on "lose" trials, where drawing a red bean meant losing $1. These results were predicted from the concretive and experiential principles of cognitive-experiential self-theory. Nonoptimal choices in the laboratory were significantly correlated with heuristic responses to relevant vignettes and with self-reported gambling in real life.

Adult↗
PubMed2000

The pleasures and pains of distinct self-construals: the role of interdependence in regulatory focus.

Regulatory focus theory distinguishes between self-regulatory processes that focus on promotion and prevention strategies for goal pursuit. Five studies provide support for the hypothesis that these strategies differ for individuals with distinct self-construals. Specifically, individuals with a dominant independent self-construal were predicted to place more emphasis on promotion-focused information, and those with a dominant interdependent self-construal on prevention-focused information. Support for this hypothesis was obtained for participants who scored high versus low on the Self-Construal Scale, participants who were presented with an independent versus interdependent situation, and participants from a Western versus Eastern culture. The influence of interdependence on regulatory focus was observed in both importance ratings of information and affective responses consistent with promotion or prevention focus.

Adult↗
PubMed2000

Cultural psychology of surprise: holistic theories and recognition of contradiction.

The authors tested the hypothesis that East Asians, because of their holistic reasoning, take contradiction and inconsistency for granted and consequently are less likely than Americans to experience surprise. Studies 1 and 2 showed that Korean participants displayed less surprise and greater hindsight bias than American participants did when a target's behavior contradicted their expectations. Studies 3 and 4 further demonstrated that even when contradiction was created in highly explicit ways, Korean participants experienced little surprise, whereas American participants reported substantial surprise. We discuss the implications of these findings for various issues, including the psychology of conviction, cognitive dissonance, and the development of science.

Adult↗
PubMed1988

Probability and category redefinition in the fault tree paradigm.

Fault trees have been advocated as aids for problem solvers. However, research has suggested limitations in their usefulness. Fischhoff, Slovic, and Lichtenstein (1978) found that subjects given incomplete (pruned) trees were insensitive to omissions; these authors hypothesized that Tversky and Kahneman's (1974) availability heuristic was the mediating factor. Using a within-subjects design, subjects in Experiment 1 received both full and pruned trees and estimated probabilities for various reasons why a car would fail to start. To increase the availability of omissions, some Experiment 1 subjects first generated possible causes of starting failure. The basic Fischhoff et al. findings were replicated, but several aspects of the results argued against the availability hypothesis as the mechanism for judgment. Instead, subjects appeared to idiosyncratically redefine category membership when making judgments based upon pruned trees. By employing a sorting task in Experiment 2 we corroborated the results of Experiment 1: Subjects do redefine the actual contents of the categories when faced with an omission from the fault tree. The implications of these results for the use of fault trees as a problem solving aid are discussed.

Decision Trees↗
PubMed1988

Components of the location probability effect in visual search tasks.

In visual search tasks, targets are detected more rapidly when they appear in locations that commonly contain a target than when they appear in locations that rarely contain a target. Five experiments were conducted to investigate two specific properties of this location probability effect: its dependence on spatial location versus relative position and its dependence on or independence of target identity. In Experiment 1 spatial location of a stimulus row was varied to determine whether high location probability facilitates target detection in a particular location in visual space or a particular relative position within the row. Both were facilitated to approximately the same extent. In Experiment 2 an inducing target occurred with high probability in one of four display locations, and a test target occurred with equal probability in all four locations. Both targets were found more quickly in the high-probability location than in the other locations, but the advantage associated with targets in the high-probability location was larger for the inducing target than for the test target. In Experiments 3-5 the correspondence between the components observed in Experiments 1 and 2 was examined. The overall pattern of results was compatible with a model in which the location probability effect is produced partly by an attentional spotlight, which facilitates processing of any stimulus appearing in a particular location in visual space, and partly by a network of position-specific letter detectors, which facilitates detection of a particular letter in a particular relative position within a display. Models with flexible scanning strategies were also considered.

Attention↗