When are the precursors of ordinal numerical knowledge first evident in infancy? Brannon (2002) argued that by 11 months of age, infants possess the ability to appreciate the greater than and less than relations between numerical values but that this ability experiences a sudden onset between 9 and 11 months of age. Here we present 5 experiments…

Previous studies have shown that 7.5-month-olds can track and encode words in fluent speech, but they fail to equate instances of a word that contrast in talker gender, vocal affect, and fundamental frequency. By 10.5 months, they succeed at generalizing across such variability, marking a clear transition period during which infants' word…

The present study examines coviewing of "Baby Mozart" by 6- to 18-month-old infants and their caregivers under naturalistic conditions. We had two questions. First, extending the method of Barr, Zack, Garcia, and Muentener (Infancy, 13 [2008], 30-56) to a younger population, we asked if age, prior exposure, and caregiver verbal input would predict…

What kind of featural information do infants rely on when they are trying to recognize a previously seen object? The question of whether infants use certain features (e.g., shape or color) more than others (e.g., luminance) can only be studied legitimately if visual salience is controlled, as the magnitude of feature values--how noticeable and…

Over the first years of life, infants gradually develop the ability to retrieve their memories across cue and contextual changes. Whereas maturational factors drive some of these developments in memory ability, experiences occurring within the learning event may also impact infants' ability to retrieve memories in new situations. In 2 experiments…

This study investigated the relation between maternal contingent responsiveness and 4- and 5-month-old infants' (N = 64) social expectation behavior in a still-face procedure. Mothers were asked to interact with their infants for 2 min (interactive phase), remain still-faced for 1 min (still-face phase), and resume interaction for 2 min. Mother…

Mothers modify their actions when demonstrating objects to infants versus adults. Such modifications have been called infant-directed action (IDA) or "motionese" (Brand, Baldwin, & Ashburn, 2002). We investigated the IDA features of interactiveness and simplification by quantifying eye gaze, object exchanges, and action units enacted…

This experiment investigated the impact of the path of approach of an object, from head on versus from the side, and the type of imminent contact with that object, a hit versus a miss, on young infants' perceptions of object looming. Consistent with earlier studies, we found that 4- to 5-month-old infants do indeed discriminate hits versus misses.…

Although vocalization and mouthing are behaviors frequently performed by infants, little is known about the characteristics of vocalizations that occur with objects, hands, or fingers in infants' mouths. The purpose of this research was to investigate characteristics of vocalizations associated with mouthing in 6 to 9-month-old infants during play…

Although it is generally accepted that labels facilitate categorization in infancy, recent evidence suggests that infants and young children are more likely to process visual input when presented in isolation than when paired with nonlinguistic sounds or linguistic labels. These findings suggest that auditory input (when compared to a no-auditory…

This study investigated whether acoustic input, in the form of infant-directed speech, influenced infants' segmenting of action sequences. Thirty-two 7.5- to 11.5-month-old infants were familiarized with video sequences made up of short action clips. Narration coincided with portions of the action stream to package certain pairs of clips together.…

Gergely, Bekkering, and Kiraly (2002) demonstrated that 14-month-old infants engage in "rational imitation." To investigate the development and flexibility of this skill, we tested 12-month-olds on a different but analogous task. Infants watched as an adult made a toy animal use a particular action to get to an endpoint. In 1 condition there was a…

Acoustic properties of the cries of 14 infants were evaluated at both 2 and 4 weeks of age when the infants were lying in a supine position and when they were sitting upright in a car seat. In the upright position, infants' breathing was more rapid and showed less individual variability. The fundamental frequency of their cries increased in the…

This study examined 6-month-old infants' abilities to use the visual information provided by simulated self-movement through the world, and movement of an object through the world, for spatial orientation. Infants were habituated to a visual display in which they saw a toy hidden, followed by either rotation of the point of observation through the…

Human adults are more accurate at discriminating faces from their own race than faces from another race. This "other-race effect" (ORE) has been characterized as a reflection of face processing specialization arising from differential experience with own-race faces. We examined whether 3.5-month-old infants exhibit ORE using morphed faces on which…