A label can efficiently convey nonobvious information about category membership, but this information can sometimes conflict with one's own expectations. Two studies explored whether 24-month-olds (N = 56) would be willing to accept a category label indicating that an animal (Study 1) or artifact (Study 2) that looked like a member of one familiar…

Experience with a variety of symbolic artifacts has been proposed as a mechanism underlying symbolic development. In this study, the parents of 120 2-year-old children who participated in symbolic object retrieval tasks completed a questionnaire regarding their children's naturalistic experience with symbolic artifacts and activities. In separate…

Three experiments investigated 14-, 18-, and 24- month-old infants' understanding of visual perception. Infants viewed films in which a protagonist was either able to view the location of a hidden object (Visual Access condition) or was blindfolded when the object location was revealed (No Visual Access condition). When requested to find the…

This research investigated the extent and nature of the informational support that enables young children to understand pictures as symbols. Two experiments were conducted using an object-retrieval task. The first experiment varied the amount (complete and no instructions) and kind of information (intended function of the symbol and…

In this study, we investigated relations between infants' understanding of intentional actions and measures of social responsiveness during a transitional period, 9- to 11-months. Infants (N = 52) were tested in visual habituation paradigms tapping their understanding of the relation between a person and the object of her attention. Measures of…

Mother-child dyads who experienced a devastating tornado talked about the storm and about two affectively more positive or neutral events at each of two time points: 4 months and 10 months after the storm. The conversations were analyzed to determine whether mothers and/or children's contributions differed as a function of event type and whether…

Four experiments examined children's inferences about the relation between objects' internal parts and their causal properties. In Experiment 1, 4-year-olds recognized that objects with different internal parts had different causal properties, and those causal properties transferred if the internal part moved to another object. In Experiment 2,…

This study examines the development of children's ability to reason about proportions that involve either discrete entities or continuous amounts. Six-, 8- and 10-year olds were presented with a proportional reasoning task in the context of a game involving probability. Although all age groups failed when proportions involved discrete quantities,…

We investigated the effects of different amounts of distraction on preschoolers' task performance and attention. Children 3.5 and 4 years of age completed problem-solving tasks in one of three conditions: no distraction, intermittent (periodic) distraction, or continuous distraction. The results revealed differential effects of the distractors at…

Under most circumstances, children (and adults) can safely assume that the testimony they hear is true. In two studies, we investigated whether 3-year-olds (N = 100) would continue to hold this assumption even if the person who provided the testimony behaved in an uncertain, ignorant, and/or distracted manner. In Study 1, children were less likely…

A method for eliciting extended explanations was used to evaluate predictions from the "theory-theory" account of developing psychological reasoning. Children were repeatedly asked to explain the actions or emotions of story characters with false beliefs. Questioning elicited false belief attributions in half of 3-year-olds (Study 1, N = 16, age M…

Patients with Parkinson's disease (PD) exhibit deficits in perceptual and motor timing as well as impairments in memory and attentional processes that are related to dysfunction of dopaminergic systems in the basal ganglia. The aim of the present study was to assess the relationships existing between impaired duration judgments and defective…

The effect of a visual warning signal (1.0-6.5s random foreperiod, FP) on the latency of voluntary (hand-grip) and reflexive (startle-eyeblink) reactions was investigated in Parkinson's disease (PD) patients and in young and aged control subjects. Equivalent FP effects on blink were observed across groups. By contrast, FP effects diverged for…

Studies of basal ganglia dysfunction in humans have generally involved patients with degenerative disorders, notably Parkinson's disease. In many instances, the performance of these patients is compared to that of patients with focal lesions of other brain structures such as the cerebellum. In the present report, we studied the performance of…

Parkinson's patients have been found to be impaired in learning movement sequences. In the current study, patients with unilateral basal ganglia lesions due to stroke were tested on a serial reaction time task in which responses were based on the spatial location of each stimulus. The spatial locations either followed a fixed sequence or were…