The ability to attribute 2nd-order mental states was investigated in 87 children drawn from preschool, kindergarten, lst-grade, and 2nd-grade classes. Children received 4 stories, 2 standard and 2 new, designed to test their understanding of 2nd-order mental states. The standard stories were modified versions of J. Perner and H. Wimmer's (1985) 2nd-order task. The new stories were made significantly simpler by reducing the number of characters, episodes, and scenes and by including a deception context. The main findings were that performance on the new stories was significantly better than on the standard stories and that nearly half of the preschoolers and almost all of the kindergartners were able to attribute 2nd-order beliefs. These findings contrast with earlier research.A strong consensus has emerged among theory-of-mind researchers that children first become capable of attributing mental states like belief at about the age of 4. Many researchers (e.g., Perner, 1991;Wellman, 1990) have noted, however, that the capacity to attribute second-order, or embedded, mental states (e.g., "She thinks that he thinks . . .") confers on children the capacity to understand not only a person's perception of a social situation (first-order reasoning) but also different individuals' concern about the other's mental states (second-order reasoning). It is these sorts of attributions that underlie much of our social reasoning and that are necessary for any sophisticated understanding of human action. Perner and Wimmer (1985) designed an interesting task to tap children's understanding of second-order belief. This task is based on the same paradigm that was used to investigate younger children's understanding of first-order false belief (Wimmer & Perner, 1983). They presented children with stories in which two actors, John and Mary, see an ice-cream van at the park where they are playing. Later, each is independently informed that the ice-cream van has moved from the park to the church, but neither knows that the other actor has been informed. In a series of six experiments, children between the ages of 5 and 10 were asked where John thinks Mary would go to buy an icecream. To respond correctly, children must take into account John's ignorance of Mary's knowledge of the true whereabouts of the ice-cream van. The findings across the individual experi-

A standardized clinical assessment can be used to identify the subgroup of individuals within the category of questionable AD who have a high likelihood of converting to AD over time. Subjects who met the criteria for questionable AD had a variety of trajectories during a 3-year follow-up, suggesting that diverse factors may influence the functional changes observed in this population.

4 studies investigated the broad claim that preschoolers understand biological inheritance. In Study 1, 4-7-year-old children were told a story in which a boy was born to one man and adopted by another. The biological father was described as having one set of features (e.g., green eyes) and the adoptive father as having another (e.g., brown eyes). Subjects were asked which man the boy would resemble when he grew up. Preschoolers showed little understanding that selective chains of processes mediate resemblance to parents. It was not until age 7 that children substantially associated the boy with his biological father on physical features and his adoptive father on beliefs. That is, it was not until age 7 that children demonstrated that they understood birth as part of a process selectively mediating the acquisition of physical traits and learning or nurturance as mediating the acquisition of beliefs. In Study 2, subjects were asked whether, as a boy grew up, various of his features could change. Children generally shared our adult intuitions, indicating that their failure in Study 1 was not due to their having a different sense of what features can change. Studies 3 and 4 replicated Study 1, with stories involving mothers instead of fathers and with lessened task demands. Taken together, the results of the 4 studies refute the claim that preschoolers understand biological inheritance. The findings are discussed in terms of whether children understand biology as an autonomous cognitive domain.

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The claim that preadolescent children fail to differentiate between hypothetical beliefs and evidence is investigated in 2 studies. First‐and second‐grade children were presented with 2 conflicting hypotheses and asked to choose an empirical test to decide between them. In Study 1, the majority of first graders and almost all second graders correctly chose a conclusive test. They elaborated the logic of such a test and distinguished it from an inconclusive test. There was no evidence that children of this age misinterpret the task of hypothesis testing as one of generating a desirable effect. Study 2 replicated and extended these findings; in a task that posed a genuine scientific problem, first and second graders spontaneously generated empirical procedures for gathering indirect evidence to decide between alternative hypotheses. Our results indicate that young elementary school children distinguish between the notions of “hypothetical belief” and “evidence.” These findings are discussed in light of their failure on other scientific thinking tasks.

4 studies investigated the broad claim that preschoolers understand biological inheritance. In Study 1, 4-7-year-old children were told a story in which a boy was born to one man and adopted by another. The biological father was described as having one set of features (e.g., green eyes) and the adoptive father as having another (e.g., brown eyes). Subjects were asked which man the boy would resemble when he grew up. Preschoolers showed little understanding that selective chains of processes mediate resemblance to parents. It was not until age 7 that children substantially associated the boy with his biological father on physical features and his adoptive father on beliefs. That is, it was not until age 7 that children demonstrated that they understood birth as part of a process selectively mediating the acquisition of physical traits and learning or nurturance as mediating the acquisition of beliefs. In Study 2, subjects were asked whether, as a boy grew up, various of his features could change. Children generally shared our adult intuitions, indicating that their failure in Study 1 was not due to their having a different sense of what features can change. Studies 3 and 4 replicated Study 1, with stories involving mothers instead of fathers and with lessened task demands. Taken together, the results of the 4 studies refute the claim that preschoolers understand biological inheritance. The findings are discussed in terms of whether children understand biology as an autonomous cognitive domain.

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The aim of this study was to determine the prevalence of psychiatric symptoms among nondemented individuals with memory changes and whether such symptoms predict progression of functional decline or diagnosis of Alzheimer disease (AD). A semi-structured interview was administered at baseline to controls (n = 32) and to nondemented subjects with memory changes (n = 112) and to each subject's collateral source. The interview assessed the impact of cognition on functional abilities in daily life and a variety of psychiatric symptoms, including symptoms of psychosis, depression, and personality change. Participants were followed annually for 3 years to determine who had progressive functional decline and who progressed to meet clinical criteria for AD. Those diagnosed with AD on follow-up had more symptoms of personality change, such as agitation and passivity, at baseline than those who did not progress to meet clinical criteria for AD. Mild depressive symptoms were also more common among individuals at baseline who subsequently 'converted' to AD. Symptoms of personality change were associated with a more rapid increase in functional difficulty over time, whereas depressive symptoms were not. Changes in personality are more common among subjects with memory changes who go on to develop AD. Particular types of personality change, such as agitation and passivity, are related to progression of functional difficulty over time. Depressive symptoms, although common in prodromal AD, are not associated with a more rapid functional decline.