Causal status effect in children's categorization.

The current study examined the causal status effect (weighing cause features more than effect features in categorization) in children. Adults (Study 1) and 7-9-year-old children (Study 2) learned descriptions of novel animals, in which one feature caused two other features. When asked to determine which transfer item was more likely to be an example of the animal they had learned, both adults and children preferred an animal with a cause feature and an effect feature rather than an animal with two effect features. This study is the first direct demonstration of the causal status effect in children.

The inheritance of desired characteristics: Children's view of the role of intention in parent-offspring resemblance.

Two studies examined children's beliefs about maternal intention as a mechanism for trait inheritance. In Study 1, 42 preschool-aged (4 to 5 years old) children and 81 adults were shown pictures of adult women (mothers) and were asked to identify their daughters. In the critical condition participants were asked to choose between a girl who shared an attribute with the mother and a girl who had the attribute desired by the mother. Trait types included physically heritable traits, nonheritable traits, and beliefs. Results from this study suggest that preschoolers do believe that maternal intention plays a role in the inheritance of physical traits. Study 2 was designed to determine whether preschoolers recognize limits on both the efficacy and the timing of maternal intention. Results suggest that children see some properties as outside of maternal control. Further, they do seem to see maternal intentions as operating prior to birth. One finding of these studies is that preschoolers may not have strong intuitions that offspring will resemble their parents. In addition, children seem to have different intuitions about the mechanisms of inheritance than do adults.

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.

Essentialism and graded membership in animal and artifact categories.

A number of studies have argued that people view membership in animal and artifact categories as a matter of degree. These studies have generally failed to distinguish between the issues of typicality and category membership. Thus, data which have been taken to demonstrate that membership is a matter of degree may only demonstrate that typicality is graded. Partly on the basis of these findings, it has been argued that some categories are organized around an underlying essence. The essence determines membership absolutely. The present paper reports a series of studies that reexamine the question of graded membership. In the first study, subjects were asked to rate both typicality and category membership for the same stimuli as a way of distinguishing the two questions. A second method relied on the intuition that disagreements about membership in all-or-none and graded categories may have different qualities. Results from both studies suggest some support for claims that membership in animal and artifact categories is a matter of degree. A third study explored the possibility that graded responses were due to conflicting, or ambiguous, sets of criteria. A task focusing on biological features did not lead to more absolute categorization. These results contradict essentialist predictions.

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.

On wooden pillows: multiple classification and children's category-based inductions.

Previous research has indicated that preschoolers do not distinguish between properties that are generalizable within a given category and those that are not. 2 possible general constraints on children's cognition are proposed to account for these findings. 3 studies are reported that argue against the presence of such general constraints. We examine preschoolers' understanding of the properties associated with material (e.g., wood, cotton) and object (e.g., chair, pillow) categories. In Study 1, subjects consistently made inductions based on the material compositions of items when asked to predict texture and fragility. In Study 2, the same subjects judged that items that shared material would share an unfamiliar dispositional property (e.g., gets sodden in water), but items that shared object kind would share a novel functional property (e.g., used for accelerating). Study 3 tested a younger sample of 3-year-olds and found the same sensitivity to category type, albeit with larger individual differences. By age 3, children use different modes of categorization to generalize different kinds of phenomena. These results argue against general limitations on children's abilities to use categories to make inductions. Even when children lack specific theoretical knowledge, the ability to organize phenomena into domains allows children to recognize which categories are relevant in different situations. This understanding can provide a basis for the development of more specific theories.

As time goes by: children's early understanding of growth in animals.

Beliefs about naturally occurring transformations were examined in children aged 3 to 6 years in 4 experiments. Experiment 1 tested children's understanding that animals (but not artifacts) predictably get larger over time. Experiment 1a examined whether the results obtained in the first experiment could be attributed to an added memory component on the artifact task. Experiment 2 further examined beliefs about the aging of artifacts. In Experiment 3, color and shape (metamorphosis) changes of animals were investigated. At all ages, children appeared to understand that animals get larger and not smaller with age. While older children and adults allowed for rather dramatic changes in the size and shape of animals over the life span if the alternative involved decreasing in size with age, preschool children were less willing to accept these changes. Taken together, the results of these studies suggest that even young preschool children have 2 conceptual insights about natural transformations: that they are lawful and nonrandom, and that they are domain and mechanism specific. Further, children as young as age 3 are able to go beyond the perceptual appearance of animals in making judgments about transformations caused by growth. Implications for children's understanding of personal and species identity are discussed.