Newborns' Face Recognition: The Role of Facial Movement

This study investigates the role of dynamic information in identity face recognition at birth. More specifically we tested whether semi‐rigid motion, conveyed by a change in facial expression, facilitates identity recognition. In Experiment 1, two‐day‐old newborns, habituated to a static happy or fearful face (static condition) have been tested using a pair of novel and familiar identity static faces with a neutral expression. Results indicated that newborns manifest a preference for the familiar stimulus, independently of the facial expression. In contrast, in Experiment 2 newborns habituated to a semi‐rigid moving face (dynamic condition) manifest a preference for the novel face, independently of the facial expression. In Experiment 3, a multistatic image of a happy face with different degrees of intensity was utilized to test the role of different amount of static pictorial information in identity recognition (multistatic image condition). Results indicated that newborns were not able to recognize the face to which they have been familiarized. Overall, results clearly demonstrate that newborns' face recognition is strictly dependent on the learning conditions and that the semi‐rigid motion conveyed by facial expressions facilitates identity recognition since birth.     

Effects of Seeing and Hearing Vowels on Neonatal Facial Imitation

For several decades, many authors have claimed the existence, early in life, of a tight link between perceptual and productive systems in speech. However, the question whether this link is acquired or is already present at birth remains open. This study aimed at investigating this question by employing the paradigm of neonatal facial imitation. We compared imitative responses of newborn infants presented either visual‐only, audiovisual congruent, or audiovisual incongruent models. Our results revealed that the newborns imitated significantly more quickly the movements of the model's mouth when this model was audiovisual congruent rather than visual‐only. Moreover, when observing an audiovisual incongruent model, the newborns did not produce imitative behavior. These findings, by highlighting the influence of speech perception on newborns' imitative responses, suggest that the neural architecture for perception–production is already in place at birth. The implications of these results are discussed in terms of a link between language and neonatal imitation, which could represent a precursor of more mature forms of vocal imitation and speech development in general.     

Intersensory Perception at Birth: Newborns Match Nonhuman Primate Faces and Voices

Previous studies have shown that infants, including newborns, can match previously unseen and unheard human faces and vocalizations. More recently, it has been reported that infants as young as 4 months of age also can match the faces and vocalizations of other species raising the possibility that such broad multisensory perceptual tuning is present at birth. To test this possiblity, we investigated whether newborns can match monkey facial and vocal gestures. Using a paired preference procedure, in Experiment 1 we presented pairs of different visible monkey calls in silence and then in the presence of one or the other corresponding audible call and compared preferences across the silent and in‐sound conditions. In Experiment 2 , we presented the same monkey visible calls but this time together with a tone analog of the natural calls in the in‐sound trials. We found that newborns looked longer at the matching visible call in the in‐sound condition than in the silent condition in both experiments. These findings indicate that multisensory perceptual tuning is so broad at birth that it enables newborns to integrate the facial and vocal gestures of other primates and that integration is based on newborns’ detection of audio‐visual temporal synchrony relations.     

One is Not Enough: Multiple Exemplars Facilitate Infants' Generalizations of Novel Properties

Across three experiments, we examined 9‐ and 11‐month‐olds' mappings of novel sound properties to novel animal categories. Infants were familiarized with novel animal–novel sound pairings (e.g., Animal A [red]–Sound 1) and then tested on: (1) their acquisition of the original pairing and (2) their generalization of the sound property to a new member of a familiarized category (e.g., Animal A [blue]–Sound 1). When familiarized with a single exemplar of a category, 11‐month‐olds showed no evidence of acquiring or generalizing the animal–sound pairings. In contrast, 11‐month‐olds learnt the original animal–sound mappings and generalized the sound property to a novel member of that category when familiarized with multiple exemplars of a category. Finally, when familiarized with multiple exemplars, 9‐month‐old infants learnt the original animal–sound pairing, but did not extend the novel sound property. The results of these experiments provide evidence for developmental differences in the facilitative role of multiple exemplars in promoting the learning and generalization of information.     

Olfactory Familiarization and Discrimination in Preterm and Full‐Term Newborns

The purpose of this study was to observe olfactory detection and discrimination in preterm and full‐term newborns. Infants were familiarized for 10 trials with either vanillin or anethole. On each trial, a cotton swab perfumed with one of the odors was slowly moved in front of the baby's nose for 10 sec. For half of the preterm and full‐term infants, a new odor was presented after the last familiarization trial (experimental groups). For the other half, the same odor as during familiarization was presented (control groups). Facial and head movements for both populations and heart rates for preterm infants were recorded before, during, and after odor presentation. Preterm infants reacted to the scents by increasing facial actions and heart rate but not head movements. Full‐term infants increased facial and head movements. Neither population showed a clear behavioral habituation pattern, but full‐term newborns had a significantly reduced facial reactivity on the last familiarization trial compared to preterm infants. Preterm newborns did, however, show cardiac habituation on the last familiarization trial. Preterm and full‐term infants presented with a new odor after familiarization increased responding compared to infants presented with the same odor, indicating their ability to discriminate between 2 odors. Infants' reactivity and discrimination to odors indicate preterm and full‐term newborns' ability to be attuned to their olfactory environment.     

Learning While Babbling: Prelinguistic Object‐Directed Vocalizations Indicate a Readiness to Learn

Two studies illustrate the functional significance of a new category of prelinguistic vocalizing—object‐directed vocalizations (ODVs)—and show that these sounds are connected to learning about words and objects. Experiment 1 tested 12‐month‐old infants’ perceptual learning of objects that elicited ODVs. Fourteen infants’ vocalizations were recorded as they explored novel objects. Infants learned visual features of objects that elicited the most ODVs but not of objects that elicited the fewest vocalizations. Experiment 2 assessed the role of ODVs in learning word–object associations. Forty infants aged 11.5 months played with a novel object and received a label either contingently on an ODV or on a look alone. Only infants who received labels in response to an ODV learned the association. Taken together, the findings suggest that infants’ ODVs signal a state of attention that facilitates learning.     

The Influence of Labels,Non‐Labeling Sounds,and Source of Auditory Input on 9‐ and 15‐Month‐Olds' Object Categorization

This experiment examines the joint influence of auditory and social cues on infants' basic‐level and global categorization. Nine‐ and fifteen‐month‐olds were familiarized to a series of category exemplars in an object‐examining task. Objects were introduced with a labeling phrase, a non‐labeling sound, or no sound, and auditory input was presented orally by the experimenter or played on a hidden voice recorder. Novel objects from the familiarized category and a contrasting category were then presented. Results of analyses performed on novelty preference scores indicated that infants demonstrated basic‐level categorization in all conditions. However, infants at both age levels only demonstrated global categorization when labeling phrases were introduced. In addition, labels led to global categorization in 9‐month‐olds regardless of the source of those labels; however, labels only led to global categorization in 15‐month‐olds when the labels were presented orally by the experimenter.     

5‐Month‐Olds’ Categorization of Novel Objects: Task and Measure Dependence

To examine key parameters of the initial conditions in early category learning, two studies compared 5‐month‐olds’ object categorization between tasks involving previously unseen novel objects, and between measures within tasks. Infants in Experiment 1 participated in a visual familiarization–novelty preference (VFNP) task with two‐dimensional (2D) stimulus images. Infants provided no evidence of categorization by either their looking or their examining even though infants in previous research systematically categorized the same objects by examining when they could handle them directly. Infants in Experiment 2 participated in a VFNP task with 3D stimulus objects that allowed visual examination of objects’ 3D instantiation while denying manual contact with the objects. Under these conditions, infants demonstrated categorization by examining but not by looking. Focused examination appears to be a key component of young infants’ ability to form category representations of novel objects, and 3D instantiation appears to better engage such examining.     

Infants’ sensitivity to shape changes in 2D visual forms

Research in developmental cognitive science reveals that human infants perceive shape changes in 2D visual forms that are repeatedly presented over long durations. Nevertheless, infants’ sensitivity to shape under the brief conditions of natural viewing has been little studied. Three experiments tested for this sensitivity by presenting 128 seven‐month‐old infants with shapes for the briefer durations under which they might see them in dynamic scenes. The experiments probed infants’ sensitivity to two fundamental geometric properties of scale‐ and orientation‐invariant shape: relative length and angle. Infants detected shape changes in closed figures, which presented changes in both geometric properties. Infants also detected shape changes in open figures differing in angle when figures were presented at limited orientations. In contrast, when open figures were presented at unlimited orientations, infants detected changes in relative length but not in angle. The present research therefore suggests that, as infants look around at the cluttered and changing visual world, relative length is the primary geometric property by which they perceive scale‐ and orientation‐invariant shape.     

Preverbal Infants' Ability to Encode the Outcome of Distributive Actions

This research examined whether 10‐month‐old infants expect agents to perform equal distribution of resources. In Experiment 1, infants saw a distributor performing either an equal distribution where one strawberry was given to each of two recipients, or an unequal distribution that favored one of the recipients. Infants looked longer at the unequal test event, suggesting that they expected the strawberries to be distributed equally. In Experiment 2, the potential recipients were replaced with inanimate objects to rule out a lower‐level alternative explanation of the results in Experiment 1 based on symmetric movement of the distributor. Infants' looking times did not reveal a preference for one of the two outcomes of the test events (i.e., symmetric or asymmetric movement). Experiment 3 controlled for the role of the distributive action, that is, here the distributors only removed barriers revealing strawberries that the recipients already had. No preference was observed when an equal or unequal initial allocation of resources was revealed. Experiment 4 assessed whether infants relied on affiliative information provided by the distributor's movements. The distributor made the same movements as in Experiment 1, but without distributing any strawberries, and no difference in looking times was observed. These findings support the view that preverbal infants expect agents to behave according to a simple principle: Resources are to be distributed equally among equivalent recipients. We discuss the possible links between such reactions and the emergence of an early sense of fairness.     

Trajectory Discrimination and Peripersonal Space Perception in Newborns

The ability to discriminate the trajectories of moving objects is highly adaptive and fundamental for physical and social interactions. Therefore, we could reasonably expect sensitivity to different trajectories already at birth, as a precursor of later communicative and defensive abilities. To investigate this possibility, we measured newborns' looking behavior to evaluate their ability to discriminate between visual stimuli depicting motion along different trajectories happening within the space surrounding their body. Differently from previous studies, we did not take into account defensive reactions, which may not be elicited by impending collision as newborns might not categorize approaching stimuli as possible dangers. In two experiments, we showed that newborns display a spontaneous visual preference for trajectories directed toward their body. We found this visual preference when visual stimuli depicted motion in opposite directions (approaching vs. receding) as well as when they both moved toward the peripersonal space and differed only in their specific target (i.e., the body vs. the space around it). These findings suggest that at birth human infants seem to be already equipped with visual mechanisms predisposing them to perceive their presence in the environment and to adaptively focus their attention on the peripersonal space and their bodily self.     

Development of Three‐Dimensional Completion of Complex Objects

Three‐dimensional (3D) object completion, the ability to perceive the backs of objects seen from a single viewpoint, emerges at around 6 months of age. Yet, only relatively simple 3D objects have been used in assessing its development. This study examined infants’ 3D object completion when presented with more complex stimuli. Infants (N = 48) were habituated to an “L”‐shaped object shown from a limited viewpoint; then they were tested with volumetrically complete (solid) and incomplete (hollow) versions of the object. Four‐month‐olds and 6‐month‐old girls had no preference for either display. Six‐month‐old boys and both sexes at 9.5 months of age showed a novelty preference for the incomplete object. A control group (N = 48), only shown the test displays, had no spontaneous preference. Perceptual completion of complex 3D objects requires infants to integrate multiple, local object features and thus may tax their nascent attentional skills. Infants might use mental rotation to supplement performance, giving an advantage to young boys. Examining the development of perceptual completion of more complex 3D objects reveals distinct mechanisms for the acquisition and refinement of 3D object completion in infancy.     

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.     

A Comparison of Visual Familiarization and Object‐Examining Measures of Categorization in 9‐Month‐Old Infants

Three studies were conducted to determine whether differential patterns of categorization observed in studies using visual familiarization and object‐examining measures hold up as procedural confounds are eliminated. In Experiment 1, we attempted as direct a comparison as possible between visual and object‐examining measures of categorization. Consistent with previous reports, 9‐month‐old infants distinguished a basic‐level contrast (dog–horse) in the visual task, but not in the examining task. Experiment 2 was designed to reduce levels of nonexploratory activity in an examining task; 9‐month‐olds again failed to distinguish categories of dogs and horses. In Experiment 3, we adopted a paired‐comparison test format in the object‐examining task. Infants did display a novel category preference under paired testing conditions. The results suggest that the different patterns of categorization often seen in looking and touching tasks are a reflection, not of different categorization processes, but of the differential sensitivity of the tasks.     

Newborn Body Perception: Sensitivity to Spatial Congruency

Studies on adults have demonstrated that the perception our own body can be manipulated by varying both temporal and spatial properties of multisensory information. While human newborns are capable of detecting the temporal synchrony of visuo‐tactile body‐related cues, it remains unknown whether they also utilise spatial information for body perception. Twenty newborns were presented with a video of an infant's face touched with a paintbrush, while their own face was touched either in the spatially congruent, or an incongruent, location. We found that newborns show a visual preference for spatially congruent synchronous events, supporting the view that newborns have a rudimentary sense of their own body.     

Young Infants' Performance in the Object‐Variation Version of the Above‐Below Categorization Task: A Result of Perceptual Distraction or Conceptual Limitation?

Five experiments were conducted to examine the performance of young infants on above versus below categorization tasks. Experiments 1 and 2 showed that infants did not form abstract categorical representations for above and below when familiarized with different objects depicted in a constant spatial relation relative to a horizontal bar and tested on a novel object depicted in the familiar and novel spatial relation. Experiments 3 through 5 examined perceptual‐attentional distraction versus conceptually based generalization explanations for young infant performance in the object‐variation version of the above‐below categorization task. Experiments 3 and 4 demonstrated that infants still did not form abstract categorical representations for above and below when object variation was removed from the familiarization trials or when object novelty was reduced during the preference test trials. However, Experiment 5 showed that 3‐ and 4‐month‐olds succeeded on the above versus below categorization task when familiarized with object variation and preference tested with a familiar versus novel object‐bar relation. These results indicate that young infants can form categorical representations for above and below in the object‐variation version of the above‐below categorization task, but that such representations are specific to the particular objects presented. Young infant performance in the object‐variation version of the above‐below categorization task thus reflects a conceptually based generalization limit rather than a problem of perceptual‐attentional distraction.     

The Development of Selective Attention Orienting is an Agent of Change in Learning and Memory Efficacy

This study examined whether the developmental transition from facilitation‐based orienting mechanisms available very early in life to selective attention orienting (e.g., inhibition of return, IOR) promotes better learning and memory in infancy. We tested a single age group (4‐month‐olds) undergoing rapid development of attention orienting mechanisms. Infants completed a spatial cueing task designed to elicit IOR, in which cat or dog category exemplars consistently appeared in either the cued or noncued locations. Infants were subsequently tested on a visual paired comparison of exemplars from these cued and noncued animal categories. As expected, infants showed either facilitation‐based orienting or the more mature IOR‐based orienting during spatial cueing/encoding. Infants who demonstrated IOR‐based orienting showed memory for both specific exemplars and broader category learning, whereas those who showed facilitation‐based orienting showed weaker evidence of learning. Attention orienting also interacted with previous pet experience, such that the number of pets at home influenced learning only when infants engaged facilitation‐based orienting during encoding. Learning in the context of IOR‐based orienting was stable regardless of pet experience, suggesting that selective attention serves as an online learning mechanism during visual exploration that is less sensitive to prior experience.     

Global‐Before‐Basic Object Categorization in Connectionist Networks and 2‐Month‐Old Infants

A 3‐layered backpropagation connectionist network, configured as an autoassociator, learned to form global (e.g., mammal) before basic‐level (e.g., cat) category representations from perceptual input. To test the predicted global‐to‐basic order of category learning of the network, 2‐month‐olds were administered the familiarization/novelty‐preference procedure and examined for representation of global and basic‐level categories. Infants formed a global category representation for mammals that excluded furniture but not a basic‐level representation for cats that excluded elephants, rabbits, or dogs. The empirical results are consistent with the global‐to‐basic learning sequence observed in the network simulations.     

Distributional Phonetic Learning at 10 Months of Age

Infant phonetic perception reorganizes in accordance with the native language by 10 months of age. One mechanism that may underlie this perceptual change is distributional learning, a statistical analysis of the distributional frequency of speech sounds. Previous distributional learning studies have tested infants of 6–8 months, an age at which native phonetic categories have not yet developed. Here, three experiments test infants of 10 months to help illuminate perceptual ability following perceptual reorganization. English‐learning infants did not change discrimination in response to nonnative speech sound distributions from either a voicing distinction (Experiment 1) or a place‐of‐articulation distinction (Experiment 2). In Experiment 3, familiarization to the place‐of‐articulation distinction was doubled to increase the amount of exposure, and in this case infants began discriminating the sounds. These results extend the processes of distributional learning to a new phonetic contrast, and reveal that at 10 months of age, distributional phonetic learning remains effective, but is more difficult than before perceptual reorganization.     

Picture Perception in Infants: Generalization From Two‐Dimensional to Three‐Dimensional Displays

Two experiments investigated 9‐month‐old infants’ abilities to recognize the correspondence between an actual three‐dimensional (3D) object and its two‐dimensional (2D) representation, looking specifically at representations that did not literally depict the actual object: schematic line drawings. In Experiment 1 , infants habituated to a line drawing of either a doll or a sheep and were then tested with the actual objects themselves. Infants habituated to the sheep drawing recovered to the unfamiliar but not the familiar object, showing a novelty preference. Infants habituated to the doll drawing, however, recovered to both familiar and unfamiliar objects, failing to show any preference between the two. In Experiment 2 , infants habituated to the 3D objects and were then tested with the 2D line drawings. In this case, both groups of infants showed a preference only for the novel displays. Together these findings demonstrate that 9‐month‐old infants recognize the correspondence between 3D objects and their 2D representations, even when these representations are not literal copies of the objects themselves.