Visual short‐term memory for overtly attended objects during infancy

We investigated limitations in young infants’ visual short‐term memory (VSTM). We used a one‐shot change detection task to ask whether 4‐ and 8.5‐month‐old infants (N = 59) automatically encode fixated items in VSTM. Our task included trials that consisted of the following sequence: first a brief (500 ms) presentation with a sample array of two items, next a brief (300 ms) delay period with a blank screen, and finally a test array (2,000 ms) identical to the sample array except that the color of one of the two items is changed. In Experiment 1, we induced infants to fixate one item by rotating it during the sample (the other item remained stationary). In Experiment 2, none of the items rotated. In both experiments, 4‐month‐old infants looked equally at the fixated item when it did and did not change color, providing no evidence that they encoded in VSTM the fixated item. In contrast, 8.5‐month‐old infants in Experiment 1 preferred the fixated item when it changed color from sample to test. Thus, 4‐month‐old infants do not appear to automatically encode fixated items in VSTM.     

Postural Position Constrains Multimodal Object Exploration in Infants

Recent research has revealed the important role of multimodal object exploration in infants' cognitive and social development. Yet, the real‐time effects of postural position on infants' object exploration have been largely ignored. In the current study, 5‐ to 7‐month‐old infants (N = 29) handled objects while placed in supported sitting, supine, and prone postures, and their spontaneous exploratory behaviors were observed. Infants produced more manual, oral, and visual exploration in sitting compared to lying supine and prone. Moreover, while sitting, infants more often coupled manual exploration with mouthing and visual examination. Infants' opportunities for learning from object exploration are embedded within a real‐time postural context that constrains the quantity and quality of exploratory behavior.     

Attention to Maternal Multimodal Naming by 6‐ to 8‐Month‐Old Infants and Learning of Word–Object Relations

We examined whether mothers' use of temporal synchrony between spoken words and moving objects, and infants' attention to object naming, predict infants' learning of word–object relations. Following 5 min of free play, 24 mothers taught their 6‐ to 8‐month‐olds the names of 2 toy objects, Gow and Chi, during a 3‐min play episode. Infants were then tested for their word mapping. The videotaped episodes were coded for mothers' object naming and infants' attention to different naming types. Results indicated that mothers' use of temporal synchrony and infants' attention during play covaried with infants' word‐mapping ability. Specifically, infants who switched eye gaze from mother to object most frequently during naming learned the word–object relations. The findings suggest that maternal naming and infants' word‐mapping abilities are bidirectionally related. Variability in infants' attention to maternal multimodal naming explains the variability in early lexical‐mapping development.     

The Cat is out of the Bag: The Joint Influence of Previous Experience and Looking Behavior on Infant Categorization

We examined the effect of 4‐month‐old infants' previous experience with dogs, cats, or both and their online looking behavior on their learning of the adult‐defined category of cat in a visual familiarization task. Four‐month‐old infants' (N = 123) learning in the laboratory was jointly determined by whether or not they had experience with pets at home and how much they shifted their gaze back and forth between the stimuli during familiarization. Specifically, only infants with pets at home who also exhibited high levels of switching during familiarization remembered the individual cat exemplars or formed a summary representation of those cats. These results are consistent with recent theorizing about the processes of how infants' categorical representations are formed, and provide new understanding into how infants' categorization unfolds over time.     

Is Agency Skin Deep? Surface Attributes Influence Infants' Sensitivity to Goal‐Directed Action

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. When the surface properties of the hand were obscured by a glove, however, neither 7‐ nor 12‐month‐old infants represented its actions as goal directed (Study 1). Next, infants were shown that the gloved hands were part of a person either prior to (Study 2) or during (Study 3) the habituation procedure. Infants who actively monitored the gloved person in Study 2 and older infants in Study 3 interpreted the gloved reaches as goal directed. Thus, varying the extent to which an entity is identifiable as a person impacts infants' interpretation of the entity as an agent.     

Learning Stimulus‐Location Associations in 8‐ and 11‐Month‐Old Infants: Multimodal Versus Unimodal Information

Research on the influence of multimodal information on infants' learning is inconclusive. While one line of research finds that multimodal input has a negative effect on learning, another finds positive effects. The present study aims to shed some new light on this discussion by studying the influence of multimodal information and accompanying stimulus complexity on the learning process. We assessed the influence of multimodal input on the trial‐by‐trial learning of 8‐ and 11‐month‐old infants. Using an anticipatory eye movement paradigm, we measured how infants learn to anticipate the correct stimulus–location associations when exposed to visual‐only, auditory‐only (unimodal), or auditory and visual (multimodal) information. Our results show that infants in both the multimodal and visual‐only conditions learned the stimulus–location associations. Although infants in the visual‐only condition appeared to learn in fewer trials, infants in the multimodal condition showed better anticipating behavior: as a group, they had a higher chance of anticipating correctly on more consecutive trials than infants in the visual‐only condition. These findings suggest that effects of multimodal information on infant learning operate chiefly through effects on infants' attention.     

A Comparison of Infants' Categorization in Paired and Successive Presentation Familiarization Tasks

Three experiments directly compared infants' categorization in variations of the visual familiarization task. In each experiment, 4‐ or 6‐month‐old infants were familiarized with a collection of dogs or cats and then their response to novel dogs and cats was assessed. In Experiment 1, 4‐month‐old infants responded to the exclusive distinction of dogs or cats when tested in a paired‐comparison task. In Experiments 2 and 3, 6‐month‐old infants, but not 4‐month‐old infants, responded to this same distinction in a successive presentation task, even when the amount of familiarization was equated to that of the paired comparison task. Therefore, familiarization with a particular set of stimuli does not induce infants to respond to a single category but rather they respond to different categories depending on features of the task.     

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.     

How Mothers Encourage and Discourage Infants' Motor Actions

The content of mothers' emotional, verbal, and gestural communication to their infants was examined under conditions of potential physical risk in a laboratory motor task. Mothers encouraged and discouraged their 12‐ and 18‐month‐old infants to crawl or walk down a sloping walkway. Mothers expressed positive affect on nearly every trial. They rarely expressed purely negative affect in their faces and voices, even when discouraging. Instead, they discouraged infants with a mixture of positive and negative expressions. In both encourage and discourage conditions, mothers coupled their emotional messages with rich verbal and gestural information to elicit infants' attention, regulate their location, guide their actions, and describe the situation and potential consequences of their actions. The content of mothers' communication was attuned to infants' age and locomotor experience.     

Infant Side Biases and Familiarity‐Novelty Preferences During a Serial Paired‐Comparison Task

We monitored changes in looking that emerged when 3‐ to 6‐month‐old infants were presented with 48 trials pairing familiar and novel faces. Graphic displays were used to identify changes in looking throughout the task. Many infants exhibited strong side biases produced by infants looking repeatedly in the same direction. Although an overall novelty preference was found for the group, individual infants exhibited brief novelty runs. Few infants began with a familiarity preference. We argue that variable looking patterns emerged during the task from competition between the infants' preference to look for something novel versus their tendency to look back to previous locations. Our data suggest that looking during paired‐comparison tasks is a dynamic process dependent on perceptual‐motor events happening during the task itself.     

Sensitivity to Word‐Final Phonotactics in 9‐ to 16‐Month‐Old Infants

Previous research has shown that infants begin to display sensitivities to language‐specific phonotactics and probabilistic phonotactics at around 9 months of age. However, certain phonotactic patterns have not yet been examined, such as contrast neutralization, in which phonemic contrasts are neutralized typically in syllable‐ or word‐final position. Thus, the acquisition of contrast neutralization is dependent on infants' ability to perceive certain contrasts in final position. The studies reported here test infants' sensitivity to voicing neutralization in word‐final position and infants' discrimination of voicing and place of articulation (POA) contrasts in word‐initial and word‐final position. Nine and 11‐month‐old Dutch‐learning infants showed no preference for legal versus illegal voicing phonotactics that were contrasted in word‐final position. Furthermore, 10‐month‐old infants showed no discrimination of voicing or POA contrasts in word‐final position, whereas they did show sensitivity to the same contrasts in word‐initial position. By 16 months, infants were able to discriminate POA contrasts in word‐final position, although showing no discrimination of the word‐final voicing contrast. These findings have broad implications for models of how learners acquire the phonological structures of their language, for the types of phonotactic structures to which infants are presumed to be sensitive, and for the relative sensitivity to phonemic distinctions by syllable and word position during acquisition.     

Effects of Contingent Reinforcement of Actions on Infants' Object‐Directed Reaching

The role of contingency learning was examined in 3‐month‐old infants' reaching movements. Infants in the experimental group experienced 9 min of active training during which they could move their arms in a reach‐like fashion to pull and move a mobile. Infants in the control group experienced 9 min of passive training during which they watched a mobile move. Prior to (pre‐training) and following the mobile experience (post‐training), infants in both conditions were given an opportunity to interact with a rattle placed within and out of their reach. Compared with infants in the control condition, infants in the experimental condition produced reach‐like movements more frequently during the mobile experience; they also showed a greater increase in reaching attempts from pre‐ to post‐training assessments with the rattle. These findings show that reinforcement of arm extensions and retractions increases the frequency of infants' reaching behaviors. This result suggests that the reinforcement of components of infants' behaviors may contribute to the successful assembly of these behaviors. This process could help keep infants engaged during the lengthy transition from prereaching to independent reaching.     

Complex Interrelations of Trait Vulnerabilities in Mothers and their Infants

Despite the developmental and clinical relevance of this area of inquiry, no studies have examined the interrelations of trait vulnerabilities in the affective, behavioral, and interpersonal domains between mothers and their infants. Thus, this study examined the interrelations of three trait vulnerabilities (i.e., negative affective intensity, impulsivity, and insecure attachment) between mothers and their 12‐ to 23‐month‐old infants, focusing in particular on the unique and interactive influence of these maternal trait vulnerabilities on the expression of and precursors to these traits in their infants. Mother–infant dyads (N = 101) completed several laboratory procedures, and mothers reported on their own and their infants' expressions of the trait vulnerabilities of interest. Findings from this study provide preliminary evidence for intergenerational relations between these traits and suggest that it is the confluence of trait vulnerabilities in mothers that relates to the early expression of some of these traits in infants.     

The Value of Vocalizing: 10‐Month‐Olds' Vocal Usage Relates to Language Outcomes at 15 Months

The interaction between infant's communicative competence and responsiveness of caregivers facilitates the transition from prelinguistic to linguistic communication. It is thus important to know how infants' communicative behavior changes in relation to different caregiver responses; furthermore, how infants' modification of communicative behavior relates to language outcomes. We investigated 39 10‐month‐old infants' communication as a function of mothers' attention and responses and the relationship to language outcomes at 15 months. We elicited infants' communicative behavior in three conditions: (1) joint attention: Mothers were visually attending and responding to infants' attention and interest; (2) available: Mothers were visually attending to infants, but not responding contingently to infants' attention and interest; (3) unavailable: Mothers were not attending to infants nor responding to them. Infants vocalized more when mothers attended and responded to them (conditions 1 and 2) than when mothers did not (condition 3), but infants' gesture and gesture‐vocal production did not differ across conditions. Furthermore, infants' production of a higher proportion of vocalizations in the unavailable condition relative to the joint attention condition correlated with, and predicted, infants' language scores at 15 months. Thus, infants who appear to be aware of the social effects of vocalizations may learn words better.     

Onset of Voluntary Communication: Smiling Looks to Mother

Playing infants often direct smiling looks toward social partners. In some cases the smile begins before the look, so it cannot be a response to the sight or behavior of the social partner. In this study we asked whether smiles that anticipate social contact are used by 8‐ to 12‐month‐old infants as voluntary social signals. Eighty infants—20 at each of 8, 9, 10, and 12 months of age—completed 5 tasks. The tasks assessed anticipatory smiling during toy play, means‐end understanding (2 tasks), intentional communication via gesture and vocalizations, and memory for mother's location. Across all ages, anticipatory smiling was strongly predicted by intentional gestural and vocal communication and by means‐end understanding. The findings are discussed in terms of the nature and origins of infants' voluntary communications.     

Effects of Maternal Responsiveness on Infant Responsiveness and Behavior in the Still‐Face Task

The effects of maternal responsiveness on infant responsiveness and behavior in the Still‐Face Task were longitudinally examined through infants' first 3 months. Maternal vocal responsiveness and infant vocal and smiling responsiveness significantly increased when infants were 2 months of age. Mothers showed continuity of individual differences in vocal responsiveness from the infants' newborn period. Maternal responsiveness predicted infant responsiveness within and across sessions. Compared with infants with low‐responsive mothers, infants with high‐responsive mothers were more attentive and affectively engaged during the Still‐Face Task from 1 month of age. Infants with high‐responsive mothers discriminated between the task phases with their smiling at 1 month, a month before infants with low‐responsive mothers did so. Infants in both groups discriminated between the phases with their attention and nondistress vocalizations throughout their first 3 months. Results suggest that maternal responsiveness influences infant responsiveness and facilitates infants' engagement and expectations for social interaction.     

Seven‐Month‐Old Infants Selectively Reproduce the Goals of Animate But Not Inanimate Agents

We tested 7‐month‐old infants' sensitivity to others' goals in an imitation task, and assessed whether infants are as likely to imitate the goals of nonhuman agents as they are to imitate human goals. In the current studies, we used the paradigm developed by Hamlin et. al (in press) to test infants' responses to human actions versus closely matched inanimate object motions. The experimental events resembled those from Luo and Baillargeon's (2005) looking‐time study in which infants responded to the movements of an inanimate object (a self‐propelled box) as goal‐directed. Although infants responded visually to the goal structure of the object's movement, here they did not reproduce the box's goal. These results provide further evidence that 7‐month‐olds' goal representations are sufficiently robust to drive their own manual actions. However, they indicate that infants' responses to inanimate object movements may not be robust in this way.     

Contribution of Motion Information to Maternal Face Discrimination in Infancy

The contribution of motion and feature invariant information in infants' discrimination of maternal versus female stranger faces was assessed. Using an infant controlled habituation–dishabituation procedure, 4‐ and 8‐month‐old infants (N = 62) were tested for their ability to discriminate between their mother and a female stranger in 4 different conditions varying whether motion or feature information about the faces was available. The faces were presented in a still or dynamic video image with either a positive or a negative contrast. In each condition, infants habituated to a stranger's face and then viewed, in 3 pairs of alternating novelty test trials, either a new stranger or their mother's face. Results show that motion information contributes to the 8‐month‐old infants', but not the 4‐month‐old infants' discrimination of maternal faces. These results are interpreted in relation to recent findings and models in the adult literature suggesting that there is an enhanced contribution of dynamic information in face recognition when the face is familiar. Our data confirm that from the outset, there is a complex interplay of feature and motion information in the discrimination of the mother's face when the viewing condition is not optimal.     

Maternal Disrupted Communication During Face‐to‐Face Interaction at 4 months: Relation to Maternal and Infant Cortisol Among at‐Risk Families

The study evaluated the association between maternal disrupted communication and the reactivity and regulation of the psychobiology of the stress response in infancy. Mothers and infants were recruited via the National Health Service from the 20% most economically impoverished data zones in a suburban region of Scotland. Mothers (N = 63; M age = 25.9) and their 4‐month‐old infants (35 boys, 28 girls) were videotaped interacting for 8 min, including a still‐face procedure as a stress inducer and a 5‐min coded recovery period. Saliva samples were collected from the dyads prior to, during, and after the still‐face procedure and later assayed for cortisol. Level of disruption in maternal communication with the infant was coded from the 5‐min videotaped interaction during the recovery period which followed the still‐face procedure. Severely disrupted maternal communication was associated with lower levels of maternal cortisol and a greater divergence between mothers' and infants' cortisol levels. Results point to low maternal cortisol as a possible mechanism contributing to the mother's difficulty in sensitively attuning to her infant's cues, which in turn has implications for the infant's reactivity to and recovery from a mild stressor in early infancy.