Stimulus energy does not account for 2-month-olds' face preferences

We examined the determinants of 2-month-olds' preferences among facelike and abstract patterns. Observed preferences were compared with the predictions of two preference models--one based on stimulus energy (as measured by the amplitude spectrum) and the other based on stimulus structure (as measured by the phase spectrum). It is known that the phase spectrum is the primary determinant of perceived identity to adults. Twenty-five 2-month-olds saw six pairings of four patterns: a schematic face, a lattice, a pattern composed of the amplitude spectrum of the lattice and the phase spectrum of the face, and a pattern composed of the amplitude spectrum of the face and the phase spectrum of the lattice. Only patterns with the face's phase spectrum look facelike to adults. Unlike the preferences of newborns (Kleiner, 1987), 2-month-olds' preferences could be predicted from the phase spectrum but not from the amplitude spectrum. In other words, the 2-month-olds preferred the patterns that looked facelike to adults. These results offer clear evidence that 2-month-olds' preferences for facelike patterns are not governed by stimulus energy.     

Newborns discriminate schematic faces from scrambled faces.

Newborn attention to, and discrimination of, facelike patterns was examined in three experiments employing 35 one- to three-day-old infants. Differential eye tracking and head turning to three moving stimuli (a schematic face, a scrambled face, and a luminance-matched blank) were measured in two of the three experiments. The newborns turned their eyes and heads farther to follow patterned stimuli, containing facelike features, than to a luminance-matched blank, but they did not turn farther to a stimulus with the features arranged in a facelike manner compared to features scrambled. A third experiment tested newborns' ability to discriminate between the facelike and scrambled face patterns. Using an infant-controlled procedure, infants showed similar initial fixation times and similar numbers of trials to reach a 60% response decrement criterion to both patterned stimuli. Following habituation, novelty responding indicated that infants discriminated between the schematic face and the scrambled face patterns. Although infants did not show a preference for a facelike stimulus compared to a features-scrambled pattern in the present experiments, they could discriminate the two patterns based on the internal arrangement of the facial features.     

Newborns' preference for faces: what is crucial?

Three experiments investigated whether the presence of more elements in the upper part of a configuration (i.e., up-down asymmetry) plays a role in determining newborns' preference for facelike patterns. Newborns preferred a nonfacelike stimulus with more elements in the upper part over a nonfacelike stimulus with more elements in the lower part (Experiment 1), did not show a preference for a facelike stimulus over a nonfacelike configuration equated for the number of elements in the upper part of the configuration (Experiment 2), and preferred a nonfacelike configuration located in the upper portion of the stimulus over a facelike configuration in the lower portion of the pattern (Experiment 3). Results demonstrated that up-down asymmetry is crucial in determining newborns' face preference.     

Face preference at birth: the role of an orienting mechanism

It has been proposed that newborns’ preferential orienting to faces is solely controlled by a subcortically mediated orienting mechanism (i.e. Conspec). In contrast, preferential‐looking tasks show that face preference at birth manifests itself also with measures that index fixation duration. It is possible, however, that orienting and fixation duration are confounded and only orienting matters. The present study used a revised version of the preferential‐looking technique, in which the same stimulus (i.e. a facelike or a non‐facelike pattern) was simultaneously presented to both sides of the visual field. Results showed that longer total fixation times on the facelike stimuli resulted from the sum of a greater number of brief fixations, rather than from the sum of a small number of long fixations. These findings support the hypothesis that, for facelike patterns, the duration of infant’s fixation on the stimulus is determined by the nature of the pattern that impinges on the periphery of the visual field, more than by the nature of the pattern that is being looked at.     

The movement of internal facial features elicits 7 to 8‐month‐old infants' preference for face patterns

A preference for static face patterns is observed in newborns and disappears around 3 months after birth. A previous study has demonstrated that 5‐month‐old infants prefer schematic faces only when the internal features are moving, suggesting that face‐specific movement enhances infants' preference. The present study investigates the facilitative effect of the movement of internal facial features on infants' preference. To examine infants' preference, we used animated face patterns consisting of a head‐shaped contour and three disk blobs. The inner blobs expanded and contracted to represent the opening and closing of the eyes and mouth, and were constrained to open and close only in a biologically possible vertical direction resembling the facial muscle structure. We compared infants' preferential looking time for this vertically moving (VM) face pattern with their looking time for a horizontally moving (HM) face pattern in which blobs transformed at the same speed in a biologically impossible, horizontal direction. In Experiment 1, 7 to 8‐month‐olds preferred the VM to the HM, but 5 to 6‐month‐olds did not. However, the preference was diminished in both cases when the moving face patterns were presented without contour (Experiment 2). Our results suggest that internal facial features with vertical movements promote face preference in 7 to 8‐month‐olds. Copyright © 2011 John Wiley & Sons, Ltd.     

Deployment of attention to the configuration of features in facelike patterns by ten-week-old infants

Abstract

Three experiments were conducted to investigate the response of 10-week-old infants to the configuration of features in facelike patterns. In each experiment a series of preview trials was shown before. facelike patterns were presented on test trials. Preview stimuli were schematic drawings with non-facial configurations (Experiment 1), schematic drawings with facial configurations (Experiment 2), or photographs of men's and women's faces (Experiment 3). Test stimuli in all three experiments were facelike drawings that differed in the number and the configuration of their stimulus features.     

Sensitivity to First‐Order Relations of Facial Elements in Infant Rhesus Macaques

Faces are visually attractive to both human and nonhuman primates. Human neonates are thought to have a broad template for faces at birth and prefer face‐like to non‐face‐like stimuli. To better compare developmental trajectories of face processing phylogenetically, here, we investigated preferences for face‐like stimuli in infant rhesus macaques using photographs of real faces. We presented infant macaques aged 15–25 days with human, macaque and abstract faces with both normal and linear arrangements of facial features and measured infants' gaze durations, number of fixations and latency to look to each face using eye‐tracking technology. There was an overall preference for normal over linear facial arrangements for abstract and monkey faces but not human faces. Moreover, infant macaques looked less at monkey faces than at abstract or human faces. These results suggest that species and facial configurations affect face processing in infant macaques, and we discuss potential explanations for these findings. Further, carefully controlled studies are required to ascertain whether infant macaques' face template can be considered as broad as human infants' face template. Copyright © 2013 John Wiley & Sons, Ltd.     

Complexity and facial resemblance as determinants of response to facelike stimuli by 5-and 10-week-old infants

The purpose of this experiment was to determine whether infants at 5 and at 10 weeks of age respond to facelike drawings on the basis of stimulus complexity or on the basis of degree of resemblance to the human face. Twenty-four Ss at each age were shown four patterns in which these two dimensions were varied orthogonally. Fixation time was recorded using the successive, single stimulus procedure. Results provided no evidence of response to the facial resemblance dimension at either age level. However, there was a significant complexity component in the responses of both groups. The 5-week-old infants preferred an intermediate level of stimulus complexity. Those at 10 weeks showed a linear preference for increasing levels of the complexity dimension.     

Infant perception of static two-dimensional transparency information

The present habituation – dishabituation study focused on infants' perception of static two-dimensional transparency displays. Infants 4 and 8 months of age were habituated to a transparency display. In this stimulus, each corner of a semi-transparent square surface covered a quadrant of a circle. During the posthabituation period, the infants were presented with the semi-transparent square overlay from the habituation display and a (non-transparent) square area cut out of the habituation stimulus. The 8-month-olds looked significantly longer at the non-transparent surface, meaning that they apparently recognized the other test pattern as the semi-transparent filter they had also seen during the habituation trials, and that they regarded the non-transparent test target as being novel. In contrast, the younger participants did not exhibit a novelty preference during the posthabituation trials. Control conditions tested the impact of spontaneous stimulus preferences on the results. The findings are discussed within the framework of infant pictorial depth perception. They provide further evidence for the hypothesis that infants' sensitivity to pictorial depth cues emerges between 4 – 5 and 7 – 8 months of life.     

Detecting ‘infant‐directedness' in face and voice

Five‐ and 3‐month‐old infants' perception of infant‐directed (ID) faces and the role of speech in perceiving faces were examined. Infants' eye movements were recorded as they viewed a series of two side‐by‐side talking faces, one infant‐directed and one adult‐directed (AD), while listening to ID speech, AD speech, or in silence. Infants showed consistently greater dwell time on ID faces vs. AD faces, and this ID face preference was consistent across all three sound conditions. ID speech resulted in higher looking overall, but it did not increase looking at the ID face per se. Together, these findings demonstrate that infants' preferences for ID speech extend to ID faces.     

Two‐ to three‐month‐old infants prefer moving face patterns to moving top‐heavy patterns

Newborn infants prefer face‐like patterns over non‐face‐like patterns. This preference is explained by newborns' preference for a “top‐heavy” configuration, that is, for geometric patterns that have more elements in the upper part than in the lower part of the configuration (Simion, Valenza, Macchi Cassia, Turati, & Umiltà, 2002). However, for 3‐month‐old infants, face preference cannot be explained only by a preference for “top‐heaviness” because they prefer veridical face images over top‐heavy images. The present study used geometric patterns to investigate whether 2‐ to 3‐month‐old infants' preference for face patterns exceeds their preference for top‐heavy configurations. In Experiment 1, we revealed that the infants preferred the face pattern to the top‐heavy pattern only when the internal elements of the patterns were presented with face‐like movements. This facilitative effect of internal movement was observed again in Experiment 2, in which the patterns were presented with non‐face‐like movements. These results suggest that 2‐ to 3‐month‐olds' preference for geometric face patterns is greater than their preference for top‐heavy patterns only when aided by the movement of internal elements.     

Face detection in 2‐ to 6‐month‐old infants is influenced by gaze direction and species

Humans detect faces efficiently from a young age. Face detection is critical for infants to identify and learn from relevant social stimuli in their environments. Faces with eye contact are an especially salient stimulus, and attention to the eyes in infancy is linked to the emergence of later sociality. Despite the importance of both of these early social skills—attending to faces and attending to the eyes—surprisingly little is known about how they interact. We used eye tracking to explore whether eye contact influences infants' face detection. Longitudinally, we examined 2‐, 4‐, and 6‐month‐olds' (N = 65) visual scanning of complex image arrays with human and animal faces varying in eye contact and head orientation. Across all ages, infants displayed superior detection of faces with eye contact; however, this effect varied as a function of species and head orientation. Infants were more attentive to human than animal faces and were more sensitive to eye and head orientation for human faces compared to animal faces. Unexpectedly, human faces with both averted heads and eyes received the most attention. This pattern may reflect the early emergence of gaze following—the ability to look where another individual looks—which begins to develop around this age. Infants may be especially interested in averted gaze faces, providing early scaffolding for joint attention. This study represents the first investigation to document infants' attention patterns to faces systematically varying in their attentional states. Together, these findings suggest that infants develop early, specialized functional conspecific face detection.     

Linear systems analysis of infant visual pattern preferences

Karmel's check-pattern preference data for 13-week-old infants were reanalyzed using linear systems analysis. The two-dimensional Fourier amplitude spectrum was calculated for each of his eight checkerboard and random check patterns. The mean contrast sensitivity data for 3-month-old infants of Banks and Salapatek and the spatial frequency amplitudes of the patterns were used to derive three metrics to predict the looking times observed by Karmel. One was based on the sensitivity of the visual system to the single pattern component highest above threshold (maximum amplitude), the second was based on the total amount of pattern energy above threshold (total summation), and the third was based on the maximum amplitude with summation over nearby spatial frequency components (limited summation). The predictive power of the maximum amplitude and the total summation metrics depended on whether the pattern type was checkerboard or random check. The limited summation metric predicted looking times well for both pattern types. A linear function of the logarithm of the limited summation metric accounted for 91% of the total variance in looking time.     

La socialisation des émotions chez le nourrisson: le rôle des expressions faciales contingentes des mères

Although maternal contingent responses to their infant's facial expressions of emotions is thought to play an important role in the socialization of emotions, available data are still scarce and often inconsistent To further investigate how mothers' contingent facial expressions might influence infant emotional development, we undertook to study mother‐infant dyads in four episodes of face‐to‐face interaction during the first year. Mothers' facial expressions were strongly related to their infant's facial expressions of emotions, most of their contingent responses being produced within one second following infants' facial expressions Specific patterns of responses were also found. The impact of maternal contingent responding on infants' expressive development was also examined.     

Infant habituation and generalization to differing degrees of stimulus novelty

This study examined 4-month-old infants' fixation times to familiar and novel visual patterns. Thirty-two male and 32 female infants were given 12 successive 15 sec exposures to one simple geometric pattern followed by test trials consisting of two exposures to the same pattern, two to a pattern with the same form but novel color, two with a novel form but the same color, and two with both novel form and color. Results indicated habituation of fixation times to the repeated stimulus and recovery to novel stimuli, particularly in male infants. Generalization was also obtained with less recovery to patterns with only one dimension novel than to those with both novel. Most individual infants were also found to be attending to both dimensions rather than some infants attending mainly to color changes and others attending mainly to form changes.     

Distinguishing novelty and familiarity effects in infant preference procedures

This paper considers possible problems researchers might face when interpreting the results of studies that employ variants of the preference procedure. Infants show a tendency to shift their preference from familiar to novel stimuli with increasing exposure to the familiar stimulus, a behaviour that is exploited by the habituation paradigm. This change in attentional preference with exposure leads us to suggest that researchers interested in infants' pre‐experimental or spontaneous preferences should beware of the potentially confounding effects of exposing infants to familiarization trials prior to employing the preference procedure. The notion that infant attentional preference is dynamic also calls into question the use of the direction of post‐familiarization preference per se when interpreting the knowledge or strategies available to infants. We look into the results of a cross‐modal word learning study to show how the interpretation of results may be difficult when infants exhibit a significant preference in an unexpected direction. As a possible solution to this problem we propose that significant preferences in both directions should be sought at multiple intervals over time. Copyright © 2004 John Wiley & Sons, Ltd.     

Infants' response to facelike patterns: Developmental changes between 10 and 15 weeks of age

Infants at two age levels were shown six patterns which represented three levels of stimulus complexity and two types of organization, facial and nonfacial. Ten-week-old infants showed a preference for the higher levels of complexity but acted as though they were oblivious to the type of organization which was imposed on the elements within the stimulus patterns. Fifteen week olds also showed increased attention to the higher levels of complexity. In addition, at the older age level differential responding was greater for stimuli which varied concomitantly in both facial resemblance and complexity (Facial organization) than for those which varied only in complexity (Nonfacial organization). The present results agree with those of previous studies in suggesting that there is a change between the ages of 10 and 15 weeks in the dimensions which underlie infants' response to facelike patterns.     

Bias in proportion judgments: the cyclical power model

When participants make part-whole proportion judgments, systematic bias is commonly observed. In some studies, small proportions are overestimated and large proportions underestimated; in other studies, the reverse pattern occurs. Sometimes the bias pattern repeats cyclically with a higher frequency (e.g., overestimation of proportions less than .25 and between .5 and .75; underestimation otherwise). To account for the various bias patterns, a cyclical power model was derived from Stevens' power law. The model proposes that the amplitude of the bias pattern is determined by the Stevens exponent, beta (i.e., the stimulus continuum being judged), and that the frequency of the pattern is determined by a choice of intermediate reference points in the stimulus. When beta < 1, an over-then-under pattern is predicted; when beta > 1, the under-then-over pattern is predicted. Two experiments confirming the model's assumptions are described. A mixed-cycle version of the model is also proposed that predicts observed asymmetries in bias patterns when the set of reference points varies across trials.     

Uncertainty matters: impact of stimulus ambiguity on infant social referencing

Most infant social referencing studies have assumed that infants would be more likely to engage in social looking and be influenced by adults' message when a context is ambiguous. The present study empirically tested the effect of stimulus ambiguity on infants' referencing behaviours, with three different stimuli (positive, ambiguous, and negative), two different messages (happy and fearful), two different message providers (mother and stranger), and in two age groups (12 and 16 month olds). A typical social referencing paradigm was used and infants' social looking and regulation were measured. Infants looked at adults more frequently and faster during ambiguous situations than during unambiguous situations. They also tended to regulate their affect and behaviour based on adults' message only towards ambiguous toys. Older infants tended to look at adults faster, and showed stronger reactions towards ambiguous stimuli than younger infants, suggesting that infants' social development may moderate the effect of stimulus ambiguity on social referencing. Overall, results indicated that the ambiguity postulate is a legitimate assumption for infant social referencing. Copyright © 2010 John Wiley & Sons, Ltd.     

Beyond U-Shaped Development in Infants' Processing of Faces: An Information-Processing Account

The development of the "inversion" effect in face processing was examined in infants 3 to 6 months of age by testing their integration of the internal and external features of upright and inverted faces using a variation of the "switch" visual habituation paradigm. When combined with previous findings showing that 7-month-olds use integrative processing of an upright face, but featural processing of an inverted face (Cohen & Cashon, 2001a), the present findings suggest that from 3 to 7 months, infants' ability to integrate facial features follows an N-shaped developmental pattern for upright faces and an inverted U-shaped pattern for inverted faces. We discuss these results in terms of a set of domain-general information-processing principles.