Studied 715 twins and singletons to document heritable influences on temperament during toddler and preschool ages. Found substantial shared environmental influence on positive affect and additive genetic influence on emotion regulation. Intraclass correlations from many scales showed no evidence of "too-low" dizygotic correlations that…

Three experiments document that conceptual knowledge influences lexical acquisition in infancy. A novel target object was initially labeled with a novel word. In both yes-no (Experiment 1) and forced-choice (Experiment 2) tasks, 2-year-olds' subsequent extensions were mediated by the conceptual description of the targets. When targets were…

An important issue for understanding early cognition is why very young children's real-world representations do not get confused by pretense events. One possible source of information for children is the pretender's behaviors. Pretender behaviors may vary systematically across real and pretend scenarios, perhaps signaling to toddlers to interpret…

Although observational learning by children may occur through imitating a modeler's actions, it can also occur through learning about an object's dynamic affordances- a process that M. Tomasello (1996) calls "emulation." The relative contributions of imitation and emulation within observational learning were examined in a study with 14- to…

Preferential-looking studies suggest that by 2 months of age, infants may have knowledge about some object properties, such as solidity. Manual search studies of toddlers examining these same concepts, however, have failed to provide evidence for the same understanding. Investigators have recently attempted to reconcile this disparity but failed…

Spatial matching--the ability to distribute search effort in accord with the distribution of hidden resources--was studied in 18- to 54-month-old children. The principal development was the appropriate use of win-shift response. (Author/RWB)

Tested the hypothesis that understanding of the pretend-real distinction develops earlier than understanding of the theoretically related apparent-real distinction. Found 3-year-old children consistently performed better on pretend-real tasks than on apparent-real tasks, even when the tasks were identical except for the distinction tested. (SKC)

Provided 2- and 2.5-year-olds with partial visual information about a ball's path as it moved toward a hiding place. Found that both age groups were equally proficient at tracking the ball as it rolled behind a transparent screen with 4 opaque doors, but 2.5-year-olds were more likely to reach to the correct door when asked to find the ball.…

When imitated, toddlers were more likely to continue to act on an object; if continuing, repeat the same action on the object; generate games, especially imitation games, and look at their partner's face. These social influence processes are thought to operate naturally in peer interactions and contribute to the behavioral organization that…

In 3 experiments, 2 year olds imitated sentences that contained English or non-English functors (articles and verb inflections), and were controlled for suprasegmental and segmental factors. Children omitted English functors more often than non-English functors, thus indicating perceptual sensitivity to familiar elements. (RH)

A group of 111 2- and 3-year olds were tested on 3 phonological memory (PM) measures to ascertain whether PM skills could be assessed in children younger than 4 years of age. Results indicated that PM skills can be reliably assessed in very young children by using conventional serial span and repetition procedures. (MDM)

Examined 2-, 2.5-, and 3-year-olds' reasoning while searching for a ball that had been rolled behind an occluder. Found only 3-year-olds were able to reliably select the correct door; all children could retrieve a toy hidden in the same apparatus if it was hidden from the front by opening a door; and younger children used a variety of strategies.…

Four studies examined 2- and 3-year olds' word order and verb morphology productivity. Findings indicated that younger children neither used nor comprehended word order with novel transitive verbs. Older children comprehended and used word order to mark verbs' agents and patients. Children as young as 25 months added "-ing" but not…

Three experiments tested 21- and 27-month olds' ability to construct a path to a mentally re-presented goal. After seeing the goal-state configuration of problems, both age groups evinced planning. Demonstration of initial solution step was less effective than goal-state exposure. Even with specification of a greater proportion of the goal path,…

The putative association between fear-related behaviors and peripheral sympathetic and neuroendocrine reactivity has not been replicated consistently. This inconsistency was addressed in a reexamination of the characterization of children with extreme fearful reactions by focusing on the match between distress behaviors and the eliciting context.…