Behavioral flexibility--the ability to tailor motor actions to changing body-environment relations--is critical for functional movement. Navigating the everyday environment requires the ability to generate a wide repertoire of actions, select the appropriate action for the current situation, and implement it quickly and accurately. We used a new,…

Infants learn nouns during object-naming events--moments when caregivers name the object of infants' play (e.g., ball as infant holds a ball). Do caregivers also label the actions of infants' play (e.g., roll as infant rolls a ball)? We investigated connections between mothers' verb inputs and infants' actions. We video-recorded 32 infant-mother…

Affordances--possibilities for action--are constrained by the match between actors and their environments. For motor decisions to be adaptive, affordances must be detected accurately. Three experiments examined the correspondence between motor decisions and affordances as participants reached through apertures of varying size. A psychophysical…

How do infants learn to perceive the backs of objects that they see only from a limited viewpoint? Infants' 3-dimensional object completion abilities emerge in conjunction with developing motor skills--independent sitting and visual-manual exploration. Infants at 4.5 to 7.5 months of age (n = 28) were habituated to a limited-view object and tested…

A critical aspect of perception-action coupling is the ability to modify ongoing actions in accordance with variations in the environment. Infants' ability to modify their gait patterns to walk down shallow and steep slopes was examined at three nested time scales. Across sessions, a microgenetic training design showed rapid improvements after the…

Nativist and constructivist approaches to the study of development share a common emphasis on characterizing beginning and end states in development. This focus has highlighted the question of preservation and transformation--whether core aspects of the adult end state are present in the earliest manifestations during infancy. In contrast, a…

The social cognition and perception-action literatures are largely separate, both conceptually and empirically. However, both areas of research emphasize infants' emerging abilities to use available information--social and perceptual information, respectively--for making decisions about action. Borrowing methods from both research traditions, this…

Examined how infants acquire adaptive locomotion in the novel task of going up and down slopes. Found that infants' judgments became increasingly accurate and exploration became increasingly efficient, with no transfer over the transition from crawling to walking. Infants learned to gauge their abilities on-line as they encountered each hill at…

Examined influence of child's sex on mothers' expectations about their 11-month-olds' motor development. Found that mothers of girls underestimated their performance on the novel task of crawling down steep and shallow slopes and mothers of boys overestimated their performance. Girls and boys exhibited identical levels of motor performance during…

Examined longitudinally the effects of infants' age, body dimensions, and experience on the development of crawling. Although most infants displayed multiple crawling postures en route to walking, development did not adhere to a strict progression of obligatory, discrete stages. Duration of experience with earlier forms of crawling predicted the…

Two experiments examined problem solving in 16-month-olds' adaptive locomotion (crossing bridges of varying width with/without handrail). Findings indicated that toddlers attempted wide bridges more than narrow ones. Attempts on narrow bridges depended on handrail presence. Toddlers had longer latencies, examined bridge/handrail more closely, and…

Used kinematic measures to compare relative contributions of growing body dimensions, age, and walking experience in walking skill development in 9- to 17-month-olds, kindergartners, and college students. Found that with increased age, size, and experience, children's steps became longer, narrower, straighter, and more consistent, reflecting a…