The Microstructure of Infants' Gaze as They View Adult Shifts in Overt Attention

We presented infants (5, 6, 9, and 12 months old) with movies in which a female model turned toward and fixated 1 of 2 toys placed on a table. Infants' gaze was measured using a Tobii 1750 eye tracker. Six‐, 9‐, and 12‐month‐olds' first gaze shift from the model's face (after the model started turning) was directed to the attended toy. The 5‐month‐olds performed at random. Following this initial response, 5‐, 6‐, and 9‐month‐olds performed more gaze shifts to the attended target; 12‐month‐olds performed at random. Infants at all ages displayed longer looking times to the attended toy. We discuss a number of explanations for 5‐month‐olds' ability to follow a shift in overt attention by an adult after an initially random response, including the possibility that infants' initial gaze response strengthens the representation of the objects in the peripheral visual field.     

Six‐Month‐Olds Comprehend Words That Refer to Parts of the Body

Comprehending spoken words requires a lexicon of sound patterns and knowledge of their referents in the world. Tincoff and Jusczyk (1999) demonstrated that 6‐month‐olds link the sound patterns “Mommy” and “Daddy” to video images of their parents, but not to other adults. This finding suggests that comprehension emerges at this young age and might take the form of very specific word‐world links, as in “Mommy” referring only to the infant’s mother and “Daddy” referring only to the infant’s father. The current study was designed to investigate if 6‐month‐olds also show evidence of comprehending words that can refer to categories of objects. The results show that 6‐month‐olds link the sound patterns “hand” and “feet” to videos of an adult’s hand and feet. This finding suggests that very early comprehension has a capacity beyond specific, one‐to‐one, associations. Future research will need to consider how developing categorization abilities, social experiences, and parent word use influence the beginnings of word comprehension.     

Toddlers’ Responses to Infants’ Negative Emotions

Early developments in toddlers’ responses to adults’ distress have been extensively examined, but less work has been directed to young children's responses to other children in distress. In the current study, we examined 12‐, 18‐, and 24‐month‐old children's (N = 71) behavioral and affective responses to a crying infant (doll) present in the room with the child. A comparison condition included a contented, neutral infant to contrast with the crying infant so as to disambiguate social interest from distress‐specific responding. Results showed that 12‐month‐olds were neither particularly interested in nor concerned about the infant, although they did discriminate between conditions. In contrast, 18‐ and 24‐month‐olds were socially interested and attentive to the infant, but 24‐month‐olds exhibited greater affective concern to the crying infant than did 18‐month‐olds. Children at all three ages were also mildly distressed themselves by the infant's crying, and this did not decline over the second year. Both girls and children without siblings were more interested in the infant; no effects were found for gender, daycare experience, or siblings on affective concern.     

2‐Year‐Olds’ Speech Understanding in Multitalker Environments

Infants and toddlers are often spoken to in the presence of background sounds, including speech from other talkers. Prior work has suggested that infants 1 year of age and younger can only recognize speech when it is louder than any distracters in the environment. The present study tests 24‐month‐olds’ ability to understand speech in a multitalker environment. Children were presented with a preferential‐looking task in which a target voice told them to find one of two objects. At the same time, multitalker babble was presented as a distracter, at one of four signal‐to‐noise ratios. Children showed some ability to understand speech and look at the appropriate referent at signal‐to‐noise ratios as low as ?5 dB. These findings suggest that 24‐month‐olds are better able to selectively attend to an interesting voice in the context of competing distracter voices than are younger infants. There were significant correlations between individual children’s performance and their vocabulary size, but only at one of the four noise levels; thus, it does not appear that vocabulary size is the driving factor in children’s listening improvement, although it may be a contributing factor to performance in noisy environments.     

Picture Perception in Infants: Do 9‐Month‐Olds Attempt to Grasp Objects Depicted in Photographs?

Two experiments tested the DeLoache, Pierroutsakos, Uttal, Rosengren, and Gottlieb (1998 claim that 9‐month‐old infants attempt to grasp objects depicted in photographs. In Experiment 1, 9‐month‐olds viewed an object, a photograph of the object, and 2 flat, nonpictorial displays. On average, they reached for the photograph and nonpictorial displays with their hands approximately horizontal and close to the display surfaces, but reached for the object with their hands oriented obliquely and at significantly higher heights. The infants also exhibited similar behaviors when touching the photograph and nonpictorial displays. In Experiment 2, 9‐month‐olds exhibited similar behaviors when touching a photograph of an object and a photograph of textured carpet. The results of both experiments suggest that 9‐month‐olds treat photographs of objects as 2‐dimensional surfaces and not as graspable objects.     

Infants’ Visual Attention to Baby DVDs as a Function of Program Pacing

This study examined the effects of program pacing, defined as the rate of scene and character change per minute, on infants’ visual attention to video presentations. Seventy‐two infants (twenty‐four 6‐month‐olds, twenty‐four 9‐month‐olds, twenty‐four 12‐month‐olds) were exposed to one of two sets of high‐ and low‐paced commercial infant DVDs. Each DVD was approximately 5‐min long, and the order the DVDs were viewed was counterbalanced for pace. Attention was higher during rapidly than slowly paced DVDs, particularly for the 6‐ and 9‐month‐old infants. These results support previous research documenting that attention is initially controlled by exogenous qualities (e.g., rapid pace), but with development and experience becomes more influenced by endogenous factors.     

Infants Discriminate the Affective Expressions of their Peers: The Roles of Age and Familiarization Time

Research examining infants’ discrimination of affect often uses unfamiliar faces and voices of adults. Recently, research has examined infant discrimination of affect in familiar faces and voices. In much of this research, infants were habituated to the affective expressions using a “standard” 50% habituation criterion. We extend this line of research by examining infants’ discrimination of unfamiliar peers’, that is, 4‐month‐olds, dynamic, facial, and vocal affective expressions and assessing how discrimination is affected by changing the habituation criterion. In two experiments, using an infant‐controlled habituation design, we explored 3‐ and 5‐month‐olds’ discrimination of their peers’ dynamic audiovisual displays of positive and negative expressions of affect. Results of Experiment 1, using a 50% habituation criterion, revealed that 5‐month‐olds, but not 3‐month‐olds discriminated the affective expressions of their peers. In Experiment 2, we examined whether 3‐month‐olds’ lack of discrimination in Experiment 1 was a result of insufficient habituation (i.e., familiarization). Specifically, 3‐month‐olds were habituated using a 70% habituation criterion, providing them with longer familiarization time. Results revealed that using the more stringent habituation criterion, 3‐month‐olds showed longer habituation times, that is increased familiarization, and discriminated their peers’ affective expressions. Results are discussed in terms of infants’ discrimination of affect, the role of familiarization time, and limitations of the 50% habituation criterion.     

12‐Month‐Olds Produce Others' Intended but Unfulfilled Acts

Following Meltzoff's (1995) behavioral reenactment paradigm, this study investigated the ability of 12‐month‐olds (N = 44) to reproduce a model's attempted‐but‐failed actions on objects. Testing was conducted using a novel set of objects designed to enable young infants to readily identify the potential outcome of the model's actions. Infants who saw an adult's attempted‐but‐failed actions now produced her intended outcomes at an equivalent rate to infants who saw the model's completed acts, and significantly more so than infants who either observed an adult manipulating the test apparatus using nontarget actions or who did not see any actions demonstrated on the test apparatus. This result shows that, contrary to previous studies, 12‐month‐olds can produce the intended but unconsummated acts of others.     

Encoding Action Roles in Meaningful Social Interaction in the First Year of Life

Previous research has shown that 6‐ to 9‐month‐old infants detect role reversals in dyadic interaction involving 2‐argument relations. These studies extend this line of research to a 3‐argument structure: An agent gives an object to a recipient. We conducted 4 experiments in a novelty‐preference paradigm. Infants were habituated to videotaped sequences of a puppet giving a flower to another puppet. In the test phase, the puppets' spatial positions were switched, and infants alternately saw role‐reversal and direction‐reversal trials. Results indicate that 10.5‐ and 12‐month‐olds but not 9‐month‐olds selectively encoded the change of action role (agent‐recipient) over a change in the spatiotemporal properties of the interaction and that action role encoding was specific to intentional relations in a 3‐argument structure. Thus, infants at the end of their 1st year seem to be sensitive to movement cues that specify intentional relations between an agent and a recipient.     

Infant Perception of Surface Texture and Relative Height as Distance Information: A Preferential‐Reaching Study

Two preferential‐reaching experiments explored 5‐ and 7‐month‐olds’ sensitivity to pictorial depth cues. In the first experiment, infants viewed a display in which texture gradients, linear perspective of the surface contours, and relative height in the visual field provided information that two objects were at different distances. Five‐ and 7‐month‐old infants reached preferentially for the apparently nearer object under monocular but not binocular viewing conditions, indicating that infants in both age groups respond to pictorial depth cues. In the second experiment, texture gradients and linear perspective of the surface contours were eliminated from the experimental display, making relative height the sole pictorial depth cue. Seven‐month‐olds again reached more often for the apparently nearer object under monocular, but not binocular viewing conditions. By contrast, the 5‐month‐olds’ reaching behavior did not differ between viewing conditions. These results indicate that 7‐month‐olds respond to the depth cue of relative height but provide no evidence of responsiveness to relative height in 5‐month‐olds. Both age groups responded more consistently to pictorial depth in Experiment 1 than in Experiment 2.     

Follow My Gaze: Face Race and Sex Influence Gaze‐Cued Attention in Infancy

Using the eye gaze of others to direct one's own attention develops during the first year of life and is thought to be an important skill for learning and social communication. However, it is currently unclear whether infants differentially attend to and encode objects cued by the eye gaze of individuals within familiar groups (e.g., own race, more familiar sex) relative to unfamiliar groups (e.g., other race, less familiar sex). During gaze cueing, but prior to the presentation of objects, 10‐month‐olds looked longer to the eyes of own‐race faces relative to 5‐month‐olds and relative to the eyes of other‐race faces. After gaze cueing, two objects were presented alongside the face and at both ages, infants looked longer to the uncued objects for faces from the more familiar‐sex and longer to cued objects for the less familiar‐sex faces. Finally, during the test phase, both 5‐ and 10‐month‐old infants looked longer to uncued objects relative to cued objects but only when the objects were cued by an own‐race and familiar‐sex individual. Results demonstrate that infants use face eye gaze differently when the cue comes from someone within a highly experienced group.     

Mental Rotation of Dynamic,Three‐Dimensional Stimuli by 3‐Month‐Old Infants

Mental rotation involves transforming a mental image of an object so as to accurately predict how the object would look if it were rotated in space. This study examined mental rotation in male and female 3‐month‐olds, using the stimuli and paradigm developed by Moore and Johnson (2008) . Infants were habituated to a video of a three‐dimensional object rotating back and forth through a 240° angle around the vertical axis. After habituation, infants were tested both with videos of the same object rotating through the previously unseen 120° angle, and with the mirror image of that display. Unlike females, who fixated the test displays for approximately equal durations, males spent significantly more time fixating the familiar object than the mirror‐image object. Because familiarity preferences like this emerge when infants are relatively slow to process a habituation stimulus, the data support the interpretation that mental rotation of dynamic three‐dimensional stimuli is relatively difficult—but possible—for 3‐month‐old males. Interpretation of the sex differences observed in 3‐ and 5‐month‐olds’ performances is discussed.     

New Tool,New Function? Toddlers' Use of Mutual Exclusivity When Mapping Information to Objects

Prior research has suggested that 24‐month‐old toddlers will rapidly map the function of a novel object but that, unlike preschoolers and adults, they will use the tool for other purposes as well. Here, this nonexclusive pattern of object use was explored. Because it has been unclear whether a mature “one tool, one function” bias in assigning object functions is rooted in deployment of general learning principles or artifact‐specific thinking, Study 1 explored 24‐month‐olds' exploitation of social‐pragmatic cues when mapping labels, facts, and functions to novel objects. Results demonstrated that toddlers readily used a principle of mutual exclusivity to constrain assignments of labels and facts but not functions. This performance was corroborated in Study 2. It appears that 24‐month‐olds have a developing understanding that artifacts have specialized functions but that mutual exclusivity does not guide this development.     

The Development of Gaze Following in a Third‐Party Context

Infants follow the gaze of an individual with whom they are directly interacting by the end of the first year. By 18 months infants are capable of learning novel words in observational (or third‐party) contexts (Floor & Akhtar, 2006). To examine third‐party gaze following in 12‐ and 18‐month‐olds, the parent and experimenter engaged in a conversation while the infant was present. For 8 trials approximately every 30 sec the experimenter would turn her head to the right or left to fixate on a toy placed on either side of the room with the parent following suit. In the first experiment, the parent was seated next to the infant and the experimenter opposite, whereas in the second experiment the positions of the adults were switched. In Experiment 1, 18‐month‐olds but not 12‐month‐olds followed gaze. In Experiment 2, 12‐month‐olds acquired a tendency to follow gaze during the experimental session. These results suggest that an incipient ability to follow third‐party gaze is present by 12 months and that infants acquire a more reliable and general ability to follow the gaze of noninteractive others between 12 and 18 months.     

Attention to Multiple Cues During Spontaneous Object Labeling

It is well established that 2‐year‐olds attribute a novel label to an object’s global shape rather than local features (i.e., parts). Although recent studies have found that younger infants also attend to global rather than local features when given a label, the test stimuli in these experiments confounded parts and shape by varying both or neither. With infants (16‐ and 24‐month‐olds) and adults, this experiment disentangled shape and parts with appropriate test objects. Results showed a clear development of a strategy incorporating multiple cues. Across three age groups, there was an increase in generalizing labels to objects matching the exemplar’s local and global features (parts, base, and shape), and a decrease to objects matching in only one local feature. We discuss these results in terms of a learned flexibility in using multiple cues to predict lexical categories.     

Role Reversal Imitation and Language in Typically Developing Infants and Children With Autism

Three types of role reversal imitation were investigated in typically developing 12‐ and 18‐month‐old infants and in children with autism and other developmental delays. Many typically developing infants at both ages engaged in each of the 2 types of dyadic, body‐oriented role reversal imitation: self‐self reversals, in which the adult acted on herself and the child then acted on himself, and other‐other reversals, in which the adult acted on the child and the child then acted back on the adult. However, 12‐month‐olds had more difficulty than 18‐month‐olds with triadic, object‐mediated role reversals involving interactions around objects. There was little evidence of any type of role reversal imitation in children with autism. Positive relations were found between role reversal imitation and various measures of language development for 18‐month‐olds and children with autism.     

The Role of Dyadic Coordination in Organizing Visual Attention in 5‐Month‐Old Infants

In human infants, the ability to share attention with others is facilitated by increases in attentional selectivity and focus. Differences in early attention have been associated with socio‐cognitive outcomes including language, yet the social mechanisms of attention organization in early infancy have only recently been considered. Here, we examined how social coordination between 5‐month‐old infants and caregivers relate to differences in infant attention, including looking preferences, span, and reactivity to caregivers’ social cues. Using a naturalistic play paradigm, we found that 5‐month‐olds who received a high ratio of sensitive (jointly focused) contingent responses showed strong preferences for objects with which their caregivers were manually engaged. In contrast, infants whose caregivers exhibited high ratios of redirection (attempts to shift focus) showed no preferences for caregivers’ held objects. Such differences have implications for recent models of cognitive development, which rely on early looking preferences for adults’ manually engaged objects as a pathway toward joint attention and word learning. Further, sensitivity and redirectiveness predicted infant attention even in reaction to caregiver responses that were non‐referential (neither sensitive nor redirective). In response to non‐referentials, infants of highly sensitive caregivers oriented less frequently than infants of highly redirective caregivers, who showed increased distractibility. Our results suggest that specific dyadic exchanges predict infant attention differences toward broader social cues, which may have consequences for social‐cognitive outcomes.     

Development of Vocal Protests From 3 to 18 Months

Infants often protest the activities of their caregivers, and this particular social interaction may provide an important window on early communication and its development. This study used naturalistic methods to investigate the development of vocal protests. Fifteen mother‐infant dyads at each of 5 ages, from 3 to 18 months, were observed at home. Maternal behaviors of caregiving and prohibiting were tallied from videotapes, as were infants' protests of these behaviors. Maternal caregiving decreased with age, but maternal prohibitions increased. There were no changes over age in the probability of protesting maternal caregiving behavior; however, 12‐month‐olds were more likely to protest prohibitions than 6‐ or 8‐month‐olds. Older infants were also more likely to use intense protests, such as screams, than younger infants. These age‐related changes were mirrored by the differences in prohibitions and protests observed between 8‐month‐olds who could crawl and those who could not. Findings from this study were related to previous research on infant crying as an important part of the prelinguistic communication system.     

Limits of Object Persistence: Young Infants Perceive Continuity of Vertical and Horizontal Trajectories,But Not 45‐Degree Oblique Trajectories

Previous research indicated that 4‐month‐old infants perceive continuity of objects moving on horizontal trajectories but appear to have difficulty processing occlusion events involving oblique trajectories. However, because perception of continuity of vertical trajectories has not been tested, it is uncertain whether this indicates a specific deficit for oblique trajectories or a specific advantage for horizontal trajectories. We evaluated the contribution of trajectory orientation and the form of occlusion in three experiments with one hundred and forty‐four 4‐month‐olds. Infants perceived continuity of horizontal and vertical trajectories under all conditions presented. However, they did not perceive continuity of an oblique (45°) trajectory under any condition. Thus, 4‐month‐olds appear unable to process continuity of a 45° trajectory. In a fourth experiment with forty‐eight 6‐ and 8‐month‐old infants, we demonstrated that by 6 months, infants' difficulty with oblique trajectories is overcome. We suggest that young infants' difficulty with markedly oblique trajectories likely relates to immature eye movement control.     

Young Infants Match Facial and Vocal Emotional Expressions of Other Infants

Research has demonstrated that infants recognize emotional expressions of adults in the first half year of life. We extended this research to a new domain, infant perception of the expressions of other infants. In an intermodal matching procedure, 3.5‐ and 5‐month‐old infants heard a series of infant vocal expressions (positive and negative affect) along with side‐by‐side dynamic videos in which one infant conveyed positive facial affect and another infant conveyed negative facial affect. Results demonstrated that 5‐month‐olds matched the vocal expressions with the affectively congruent facial expressions, whereas 3.5‐month‐olds showed no evidence of matching. These findings indicate that by 5 months of age, infants detect, discriminate, and match the facial and vocal affective displays of other infants. Further, because the facial and vocal expressions were portrayed by different infants and shared no face–voice synchrony, temporal, or intensity patterning, matching was likely based on detection of a more general affective valence common to the face and voice.