This research unites traditionally disparate developmental domains—cognition and locomotion—to examine the classic cognitive issue of the development of inhibition in infancy. In 2 locomotor A‐not‐B tasks, 13‐month‐old walking infants inhibited a prepotent response under low task demands (walking on flat ground), but perseverated under increased task demands (descending a staircase). Despite elimination of factors previously associated with infant perseveration, infants still perseverated in the difficult stairs condition. Increasing cognitive load by manipulating task difficulty affected infants' ability to inhibit repeated responses that were no longer appropriate. Evidence supports a cognitive capacity account of infant perseveration, in which infants' performance depends on allocation of cognitive and attentional resources.

This research examined developmental continuity between "cruising" (moving sideways holding onto furniture for support) and walking. Because cruising and walking involve locomotion in an upright posture, researchers have assumed that cruising is functionally related to walking. Study 1 showed that most infants crawl and cruise concurrently prior to walking, amassing several weeks of experience with both skills. Study 2 showed that cruising infants perceive affordances for locomotion over an adjustable gap in a handrail used for manual support, but despite weeks of cruising experience, cruisers are largely oblivious to the dangers of gaps in the floor beneath their feet. Study 3 replicated the floor-gap findings for infants taking their first independent walking steps, and showed that new walkers also misperceive affordances for locomoting between gaps in a handrail. The findings suggest that weeks of cruising do not teach infants a basic fact about walking: the necessity of a floor to support their body. Moreover, this research demonstrated that developmental milestones that are temporally contiguous and structurally similar might have important functional discontinuities. Keywords crawling; cruising; walking; locomotion; developmental continuity Developmental ContinuityThe question of developmental continuity-"Where do new skills come from?"-is a central and long-standing issue in developmental psychology. Proponents of developmental continuity claim that new skills grow from the seeds of prior accomplishments. One line of evidence that old and new skills are related is adjacent temporal ordering, where a new skill appears in the footsteps of its predecessor or as one skill disappears another quickly appears on the scene. A second line of evidence is physical similarity, where old and new skills are similar in form or map onto each other structurally. The most important line of evidence is shared psychological function, where the earlier and later appearing skills rely on the same underlying psychological mechanisms to accomplish the same goals. In this case, experience

In 2 experiments the authors demonstrated that adaptive locomotion can involve means-ends problem solving. Sixteen-month-old toddlers crossed bridges of varying widths in the presence or absence of a handrail. Babies attempted wider bridges more often than narrow ones, and attempts on narrow bridges depended on handrail presence. Toddlers had longer latencies, examined the bridge and handrail more closely, and modified their gait when bridges were narrow and/or the handrail was unavailable. Infants who explored the bridge and handrail before stepping onto the bridge and devised alternative bridge-crossing strategies were more likely to cross successfully. Results challenge traditional conceptualizations of tools: Babies used the handrail as a means for augmenting balance and for carrying out an otherwise impossible goal-directed task.