Explanations of variability in long-term recall typically appeal to encoding and/or retrieval processes. However, for well over a century, it has been apparent that for memory traces to be stored successfully, they must undergo a post-encoding process of stabilization and integration. Variability in post-encoding processes is thus a potential…

Two experiments used a mutual imitation paradigm to assess 9-, 14-, and 18-month-old infants' developing understanding of intentions in others. In the first study, 1 experimenter imitated the infants' actions, and another experimenter performed contingent but different actions on an identical toy. From 9 months of age, infants show discrimination…

Visual object processing in infancy is often described as proceeding from an early stage in which object features are processed independently to a later stage in which relations between features are taken into account (e.g., Cohen, 1998). Here we present the Representational Acuity Hypothesis, which argues that this behavioral shift can be…

Since the mid-1800s, experimental psychologists have been using eye movements and gaze direction to make inferences about perception and cognition in adults (Muller, 1826, cited in Boring, 1942). In the past 175 years, these oculomotor measures have been refined (see Kowler, 1990) and used to address similar questions in infants (see Aslin, 1985,…

Eye gaze has been shown to be an effective cue for directing attention in adults. Whether this ability operates from birth is unknown. Three experiments were carried out with 2- to 5-day-old newborns. The first experiment replicated the previous finding that newborns are able to discriminate between direct and averted gaze, and extended this…

Six experiments investigated infants' sensitivity to numerosity in auditory sequences. In prior studies (Lipton & Spelke, 2003), 6-month-old infants discriminated sequences of 8 versus 16 but not 8 versus 12 sounds, and 9-month-old infants discriminated 8 versus 12 but not 8 versus 10 sounds, when the continuous variables of rate, sound duration,…

This study tested the presence of the face inversion effect in 4-month-old infants using habituation to criterion followed by a novelty preference paradigm. Results of Experiment 1 confirmed previous findings, showing that when 1 single photograph of a face is presented in the habituation phase and when infants are required to recognize the same…

From Aesop to Sun Tzu, the importance of working together has long been acknowledged. Yet as long as cooperation has existed, so have the difficulties associated with it. Pooling two fields might mean twice the power, but this union also brings twice the jargon, twice the competing theories, and twice the head butting. Nonetheless, in this…

This study examined 4- and 6-month-olds' responses to static or dynamic stimuli using behavioral and heart-rate-defined measures of attention. Infants looked longest to dynamic stimuli with an audio track and least to a static stimulus that was mute. Overall, look duration declined with age to the different stimuli. The amount of time spent in…

Infants' ability to track temporarily occluded objects that moved on circular trajectories was investigated in 20 infants using a longitudinal design. They were first seen at 6 months and then every 2nd month until the end of their 1st year. Infants were presented with occlusion events covering 20% of the target's trajectory (effective occlusion…

A fundamental question of perceptual development concerns how infants come to perceive partly hidden objects as unified across a spatial gap imposed by an occluder. Much is known about the time course of development of perceptual completion during the first several months after birth, as well as some of the visual information that supports unity…

We examined 7-month-old infants' responses to 6 joy-eliciting episodes. Three episodes included and 3 did not include a major social-interactive component. Confirmatory factor analysis of infants' joy reactions in these episodes revealed that a 2-factor model significantly improved the fit over a single-factor solution. Those 2 factors represented…

Three studies investigated the role of surface attributes in infants' identification of agents, using a habituation paradigm designed to tap infants' interpretation of grasping as goal directed (Woodward, 1998). When they viewed a bare human hand grasping objects, 7- and 12-month-old infants focused on the relation between the hand and its goal.…

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…

This study investigated the developmental continuity, stability, and organization of infants' behavioral response to mild stress from 1 to 3 months of age. Changes in infant stress reactivity were expected to coincide with a suspected neurobiological shift around the 2nd month. A total of 53 infants and their mothers participated in this study. At…