Franca Agnoli

Suppressing Natural Heuristics by Formal Instruction: The Case of the Conjunction Fallacy.

Abstract A basic principle of probability is the conjunction rule, p( B ) ⩾ p( AB rather, it stems from the absence of generally useful problem-solving designs that bring extensional principles to bear on this class of problem. We predict that when helpful extensional strategies are made available, they should compete well with intensional heuristics. Two experiments were conducted, using as subjects adult women with little mathematical background. In Experiment 1, brief training on concepts of algebra of sets, with examples of their use in solving problems, reduced conjunction-rule violations substantially, compared with a control group. Evidence from similarity judgments suggested that use of the representativeness heuristic was reduced by the training. Experiment 2 confirmed these training effects and also tested the hypothesis that conjunction-rule violations are due to misunderstanding of “B” as “B and not A.” Changes in detailed wording of the propositions to be ranked produced substantial effects on judgment, but the pattern of these effects supported the hypothesis that, for the type of problem used here, most conjunction errors are due to use of representativeness or availability. We conclude that such intensional heuristics can be suppressed when alternative strategies are taught.

Development of judgmental heuristics and logical reasoning: Training counteracts the representativeness heuristic

Abstract The foundations of adult reasoning about probabilities are found in childrens reasoning about frequencies. Adult probabilistic reasoning is impaired by heuristics based on typicality or representativeness, but development of these heuristics in childhood has not been studied. Previously, typicality has only been shown to enhance childrens reasoning. In Experiment 1, however, children in Grades 3, 5, and 7 overwhelmingly judged subclasses to be larger than inclusive classes when the subclasses were typical of a given scenario. In Experiment 2 children explained these incorrect responses by reference to the frequency of the subclass in the context or by reference to the method by which the subclass is generated, in accordance with the representativeness heuristic. The same children explained correct responses by describing the inclusion relationship. Even when asked to select the most frequent class from three alternatives including typical and atypical subclasses and an inclusive class, children frequently selected the incorrect typical subclass. Experiments 3 and 4 investigated whether children could be taught to reason logically and to suppress the use of the representativeness heuristic. Both immediately, and 10 days after a brief training, children responded correctly far more often. Furthermore, childrens explanations of their answers when they were untrained emphasized the typicality of the representative subclass, but after training they emphasized logical relationships. The results are attributed to a representativeness heuristic that is acquired early, and overcome through experience and training in logical thinking.

Questionable Research Practices among Italian Research Psychologists

A survey in the United States revealed that an alarmingly large percentage of university psychologists admitted having used questionable research practices that can contaminate the research literature with false positive and biased findings. We conducted a replication of this study among Italian research psychologists to investigate whether these findings generalize to other countries. All the original materials were translated into Italian, and members of the Italian Association of Psychology were invited to participate via an online survey. The percentages of Italian psychologists who admitted to having used ten questionable research practices were similar to the results obtained in the United States although there were small but significant differences in self-admission rates for some QRPs. Nearly all researchers (88%) admitted using at least one of the practices, and researchers generally considered a practice possibly defensible if they admitted using it, but Italian researchers were much less likely than US researchers to consider a practice defensible. Participants’ estimates of the percentage of researchers who have used these practices were greater than the self-admission rates, and participants estimated that researchers would be unlikely to admit it. In written responses, participants argued that some of these practices are not questionable and they have used some practices because reviewers and journals demand it. The similarity of results obtained in the United States, this study, and a related study conducted in Germany suggest that adoption of these practices is an international phenomenon and is likely due to systemic features of the international research and publication processes.

Children's performance in mental rotation tasks: orientation‐free features flatten the slope

Studies of the development of mental rotation have yielded conflicting results, apparently because different mental rotation tasks draw on different cognitive abilities. Children may compare two stimuli at different orientations without mental rotation if the stimuli contain orientation-free features. Two groups of children (78 6-year-olds and 92 8-year-olds) participated in an experiment investigating development of the ability to mentally rotate and the ability to recognize and use orientation-free features. Children compared two stimuli, one upright and one rotated, and responded as quickly as possible indicating whether the stimuli were the same or different. The stimuli were either two panda bears or two ice-cream cones with three scoops of ice-cream of different colors. The panda bears were either identical or mirror images. The cones were either identical, mirror images, or non-mirror images. Response times increased linearly as a function of the angle of orientation when stimuli were the same and when the stimuli were mirror images. But response times were much less dependent on angle of orientation for non-mirror image stimuli. Children as young as 6 years recognized orientation-free stimulus features and responded without mentally rotating when the task permitted this strategy.

Children correlate infrequent behaviors with minority groups: a case of illusory correlation

Abstract Adults perceive an illusory correlation between negative social behaviors and membership in the smaller of two groups — the minority group ( Hamilton & Gifford, 1976 ). Two experiments investigated the development of this illusory correlation. We created pictorial stimuli showing children performing good or bad behaviors. In Experiment 1 we told participants (children in grades 1, 3, 5, and 7 and adults) that each picture depicted a child from one of two groups. Group membership and behavior were uncorrelated, but, like adults, children perceived a correlation between the smaller group and negative behaviors. Children’s attributions of good and bad behaviors to the two groups showed a weak but significant bias. Their estimations of the number of children in each group who behaved badly showed a stronger bias. Children also rated the smaller group more negatively on many dimensions. Experiment 2 showed that the illusory correlation is not dependent on social stimuli. Children performed essentially the same tasks, but good and bad behaviors were replaced by the colors red and green, and the group members were represented as squares and triangles. The results were strikingly similar to those obtained with social stimuli. In both experiments, the strength of the illusory correlation did not vary significantly with age. The results are discussed from the perspective of theories that have been proposed to account for adult behavior and the implications of no developmental trend.

Children’s Competence or Adults’ Incompetence: Different Developmental Trajectories in Different Tasks

Dual-process theories have been proposed to explain normative and heuristic responses to reasoning and decision-making problems. Standard unitary and dual-process theories predict that normative responses should increase with age. However, research has focused recently on exceptions to this standard pattern, including developmental increases in heuristic or intuitive responses. Developmental trends for normative and heuristic responses were investigated for 2 kinds of causal reasoning (if-only and covariation) problems in 2 experiments. To investigate the role of superstitious thinking in these developmental trends, in both experiments a superstitious element was added to the problem solved by half the participants. In the first experiment, 90 fifth graders, 99 seventh graders, and 153 adults responded to an if-only problem. Children performed better than adults, with normative responses decreasing and heuristic responses increasing with age. A superstitious jinx intended to reduce heuristic responses had little effect for all age groups. In the second experiment, 276 fifth graders, 344 seventh graders, and 90 adults responded to a covariation-detection problem. When win-loss ratios were equal, adults performed better than children, with normative responses increasing and heuristic responses decreasing with age. When win-loss ratios were strikingly different, however, even the youngest children were able to solve the problems correctly; participants of all ages responded about equally well. When the normative response required recognizing that a good-luck ritual led to better team performance, participants in all age groups responded skeptically that the ritual had no effect, illustrating belief bias. These results are discussed in terms of dual-process theories and the development of heuristic (or intuitive) and analytical processes.

Comprehension of two types of negative comparisons in children

English-speaking and Italian-speaking children between the ages of 6 years 8 months and 9 years 10 months were asked to solve instructional relation problems (i.e., to complete a picture on the basis of a sentence). Sentences contained either marked or unmarked adjectival forms in one of three types of comparative construction:positive comparative (e.g., “bigger” “più grande”),negative-equative constructions as explicit negative forms (e.g., “not as big as,” “non è grande come”), orcomparative-with-less constructions e.g., “less big,” “meno grande”) as implicit negative forms. Subjects had to focus on either the grammatical subject or the grammatical object of a sentence to complete, the picture. Three findings were consistent with predictions derived by considering syntactic and pragmatic differences between explicit and implicit types of negative comparisons. First, comprehension depended on the type of comparative construction, with the poorest comprehension for the implicit comparative-with-less construction. Second, the effect of the marked adjective depended on the type of comparison. Third, in all three types of comparison, accuracy was greater when the question was focused on the grammatical subject instead of the grammatical object.

The effect of stimulus variability on children's judgements of quantity

This study investigates the effect of stimulus variability on development of the ability to make quantity judgements related to area. Participants were 241 children (aged 4, 5, 6, 8, and 12 years) and 82 university students, who were asked to compare the quantities in 2 sets of 5 chocolate bars of constant width but variable length. Participants indicated which set contained more chocolate or that the amounts of chocolate were equal. Judgement accuracy of 12-year-olds and adults decreased monotonically as the variance of bar lengths increased. In younger children, performance was low when variance was very low or very high, but accuracy was higher for intermediate levels of variance, thus resulting in an inverted U-shaped effect. This pattern was confirmed in a second experiment in which we controlled for a possible age-related response bias against “equal” judgements. Findings suggest that judgements of quantity are based on a mixture of learned heuristics and comparisons of approximate quantity representations, both of which develop throughout childhood.