Why essences are essential in the psychology of concepts.
Explore the source record for details and available documents.
Adult↗
Biomedical subjects
W K Ahn
Publications and source records attributed to W K Ahn.
Primacy in causal strength judgments: the effect of initial evidence for generative versus inhibitory relationships.
The order in which people receive information has a substantial effect on subsequent judgment and inference. Our focus is on the order of covariation evidence in causal learning. The first experiment shows that the initial presentation of evidence suggesting a generative causal relationship (the joint presence or joint absence of cause and effect) leads to higher judged causal strength than does the initial presentation of evidence suggesting an inhibitory relationship (the presence of cause or effect in the absence of the other). Additional studies show that this primacy effect is unlikely to be due to fatigue or to an insufficient number of learning trials. These results are not readily explained by current contingency-based or associative theories of causal induction.
Adult↗
Minor cutaneous features of atopic dermatitis in South Korea.
BACKGROUND: Minor cutaneous features are important in atopic dermatitis (AD) because they are related to the ethnic or genetic background and to the etiopathogenesis of the disease other than atopic allergy. In addition, they can be used as auxiliary diagnostic criteria in patients with uncertain major features. It is our experience that our AD patients have characteristic features that have not been described previously in the literature. METHODS: AD patients (n = 130) and control subjects (n = 198) were examined for the 32 conventional and seven additional minor features (sandpaper-like skin lesions on elbow/knee/lateral malleolus, hangnail, ventral wrist dermatitis, itchy hyperkeratotic papules on the dorsum of the hands, oily skin, fissured heel, and palmar erythema). The frequency of each feature was compared between AD patients and controls. The diagnostic significance of these minor features was analyzed separately in the childhood and adolescent-adult AD groups, and the age-related changes were documented. RESULTS: The seven additional features were significant for the diagnosis of AD in South Korean patients. Many of the other conventional minor features were also significant. Nine features were of diagnostic importance only in the adolescent-adult AD group, and three features were characteristic only in the childhood AD group. CONCLUSIONS: Our data suggest that ethnic backgrounds influence the phenotype of AD and that an additional seven features need to be examined to confirm the ethnic effect. As the general clinical presentation of AD is dependent upon age, the frequency of minor features varied in the different age groups.
Adolescent↗
Localized chronic urticaria at the site of healed herpes zoster.
Explore the source record for details and available documents.
Abdomen↗
Effect of causal structure on category construction.
In four experiments, the question of how the causal structure of features affects the creation of new categories was examined. Features of exemplars to be sorted were related in a single causal chain (causal chain), were caused by the same factor (common cause), or caused the same effect (common effect). The results showed that people are more likely to rely on common-cause or common-effect background knowledge than on causal-chain background knowledge in category construction. Such preferences suggest that the common-cause or the common-effect structures are considered more natural conceptual structures.
Adult↗
Feature centrality: naming versus imagining.
Being white is central to whether we call an animal a "polar bear," but it is fairly peripheral to our concept of what a polar bear is. We propose that a feature is central to category naming in proportion to the feature's category validity--the probability of the feature, given the category. In contrast, a feature is conceptually central in a representation of the object to the extent that the feature is depended on by other features. Further, we propose that naming and conceptual centrality are more likely to disagree for features that hold at more specific levels (such as is white, which holds only for the specific category of polar bear) than for features that hold at intermediate levels of abstraction (such as has claws, which holds for all bears). In support of these hypotheses, we report evidence that increasing the abstractness of category features has a greater effect on judgments of conceptual centrality than on judgments of name centrality and that other category features depend more on intermediate-level category features than on specific ones.
Adult↗
Causal attribution as a search for underlying mechanisms: an explanation of the conjunction fallacy and the discounting principle.
We propose that causal attribution involves searching for underlying mechanism information (i.e., the processes underlying the relationship between the cause and the effect). This processing account can explain both the conjunction effect (i.e., conjunctive explanations being rated more probable than their components) and the discounting effect (i.e., the effect of one cause being discounted when another cause is already known to be true). When two explanations cohere with respect to a single mechanism, they would be judged to be more likely than a single explanation which partly supports that mechanism. When the two explanations imply two separate mechanisms, one would be discounted. In Experiment 1, both effects occurred with mechanism-based explanations but not with covariation-based explanations in which the cause-effect relationship was phrased in terms of statistical covariations without referring to mechanisms. In Experiments 2 and 3, the amount of the discounting and conjunction effects varied depending on the relationships between specific mechanisms in the two given explanations. We discuss why the current results pose difficulties for previous attribution models.
Causality↗
The role of covariation versus mechanism information in causal attribution.
Traditional approaches to causal attribution propose that information about covariation of factors is used to identify causes of events. In contrast, we present a series of studies showing that people seek out and prefer information about causal mechanisms rather than information about covariation. Experiments 1, 2 and 3 asked subjects to indicate the kind of information they would need for causal attribution. The subjects tended to seek out information that would provide evidence for or against hypotheses about underlying mechanisms. When asked to provide causes, the subjects' descriptions were also based on causal mechanisms. In Experiment 4, subjects received pieces of conflicting evidence matching in covariation values but differing in whether the evidence included some statement of a mechanism. The influence of evidence was significantly stronger when it included mechanism information. We conclude that people do not treat the task of causal attribution as one of identifying a novel causal relationship between arbitrary factors by relying solely on covariation information. Rather, people attempt to seek out causal mechanisms in developing a causal explanation for a specific event.
Adult↗
Clinical evaluation of atopic hand-foot dermatitis.
Clinical manifestations of atopic hand-foot (H-F) dermatitis have not been well studied. This study examined 108 atopic dermatitis (AD) patients with H-F dermatitis between May 1997 and July 1999 at our AD clinic to determine the clinical characteristics of atopic H-F dermatitis and to assess its etiologic associations. It usually began in childhood with an early onset of AD. Pruritus was the most frequent symptom, and erythema, scales, lichenification, hyperkeratosis, fissures, and keratolysis exfoliativa were also common signs. Both the hands and feet were involved in 47 (44.0%) patients, and either hand or foot involvement was observed in 15 (13.9%) and 46 (42.6%) patients, respectively. Palmar or plantar surfaces were more frequently involved than the dorsal aspects. The great toe was affected more often than the other toes. Two-thirds of patients presented with manifestations of the ichthyosis triad and sandpaper-like skin lesions on the elbow, knee, and lateral malleolus. Palmar or plantar hyperhidrosis was reported in 15% and 20%, respectively. The ichthyosis triad-associated group showed a significantly higher incidence of sandpaper-like (thickened, roughened) skin lesions, and these patients had lesions on the dorsal hands or heels and lateral malleolus more frequently than ichthyosis triad-absent patients. The hyperhidrosis-associated group showed an association with glassy lesions, localized to palmar or plantar areas. Atopic H-F dermatitis is associated with the nonallergic etiologies of AD and clinical subgroups can be identified on the basis of nonallergic backgrounds.
Child↗