Intersensory Redundancy and 7‐Month‐Old Infants' Memory for Arbitrary Syllable‐Object Relations

Seven‐month‐old infants require redundant information, such as temporal synchrony, to learn arbitrary syllable‐object relations (Gogate & Bahrick, 1998). Infants learned the relations between 2 spoken syllables, /a/ and /i/, and 2 moving objects only when temporal synchrony was present during habituation. This article presents 2 experiments to address infants' memory for these relations. In Experiment 1, infants remembered the syllable‐object relations after 10 min, only when temporal synchrony between the vocalizations and moving objects was provided during learning. In Experiment 2, 7‐month‐olds were habituated to the same syllable‐object pairs in the presence of temporal synchrony and tested for memory after 4 days. Once again, infants learned and showed emerging memory for the syllable‐object relations 4 days after original learning under the temporally synchronous condition. These findings are consistent with the view that prior to symbolic development, infants learn and remember word‐object relations by perceiving redundant information in the vocal and gestural communication of adults.     

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.     

Development of Visual Selection in 3‐ to 9‐Month‐Olds: Evidence From Saccades to Previously Ignored Locations

We examined changes in the efficiency of visual selection over the first postnatal year with an adapted version of a spatial negative priming paradigm. In this task, when a previously ignored location becomes the target to be selected, responses to it are impaired, providing a measure of visual selection. Oculomotor latencies to target selection were the dependent measure. Each trial consisted of a prime and a probe presentation, separated by a 67‐, 200‐, or 550‐msec interstimulus interval (ISI), to test the efficiency of selection as a function of processing time. In the prime, the target was accompanied by a distractor item. In the probe, the target appeared either in the location formerly occupied by the distractor (repeated distractor trials) or in one of the other two locations (control trials). We tested 41 infants in each of 3 age groups (3, 6, and 9 months) on the three different ISIs. Nine‐month‐old infants' saccade latencies were slowed on repeated distractors relative to control trials, given sufficiently long ISIs. Saccade latencies in the youngest two age groups showed only facilitation on repeated distractor trials at short ISIs. These results suggest that visual selection efficiency is a function of the interaction of the processing limitations of a system with environmental conditions, in this case the time allotted for the selection process.     

The Effect of Social Responsiveness on Infants' Object‐Directed Imitation

Previous research has demonstrated that social interactions underlie the development of object‐directed imitation. For example, infants differentially learn object action sequences from a live social partner compared to a social partner over a video monitor; however, what is not well understood is what aspects of social interactions influence social learning. Previous studies have found variable influences of different types of caregiver responsiveness on attention, language, and cognitive development. Therefore, the purpose of this study was to examine how the responsive style of a social partner influenced the learning of object‐directed action sequences. Infants interacted with either a sensitive or redirective experimenter before the learning trial. Results revealed infants changed their patterns of engagement; infants interacting with a sensitive experimenter had longer periods of attentional engagement than infants interacting with a redirective experimenter. Furthermore, during the learning trial, the amount of sensitivity during interaction with the social partner predicted learning scores. These findings suggest that infants' attention is influenced by social partners' interactive style during ongoing interaction, which subsequently affects how infants learn from these social partners.     

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 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.     

Infants' Rapid Learning About Self‐Propelled Objects

Six experiments investigated 7‐month‐old infants' capacity to learn about the self‐propelled motion of an object. After observing 1 wind‐up toy animal move on its own and a second wind‐up toy animal move passively by an experimenter's hand, infants looked reliably longer at the former object during a subsequent stationary test, providing evidence that infants learned and remembered the mapping of objects and their motions. In further experiments, infants learned the mapping for different animals and retained it over a 15‐min delay, providing evidence that the learning is robust and infants' expectations about self‐propelled motion are enduring. Further experiments suggested that infants' learning was less reliable when the self‐propelled objects were novel or lacked faces, body parts, and articulated, biological motion. The findings are discussed in relation to infants' developing knowledge of object categories and capacity to learn about objects in the first year of life.     

Clause Segmentation by 6‐Month‐Old Infants: A Crosslinguistic Perspective

Each clause and phrase boundary necessarily aligns with a word boundary. Thus, infants' attention to the edges of clauses and phrases may help them learn some of the language‐specific cues defining word boundaries. Attention to prosodically well‐formed clauses and phrases may also help infants begin to extract information important for learning the grammatical structure of their language. Despite the potentially important role that the perception of large prosodic units may play in early language acquisition, there has been little work investigating the extraction of these units from fluent speech by infants learning languages other than English. We report 2 experiments investigating Dutch learners' clause segmentation abilities. In these studies, Dutch‐learning 6‐month‐olds readily extract clauses from speech. However, Dutch learners differ from English learners in that they seem to be more reliant on pauses to detect clause boundaries. Two closely related explanations for this finding are considered, both of which stem from the acoustic differences in clause boundary realizations in Dutch versus English.     

Influences of Infant‐Directed Speech on Early Word Recognition

When addressing infants, many adults adopt a particular type of speech, known as infant‐directed speech (IDS). IDS is characterized by exaggerated intonation, as well as reduced speech rate, shorter utterance duration, and grammatical simplification. It is commonly asserted that IDS serves in part to facilitate language learning. Although intuitively appealing, direct empirical tests of this claim are surprisingly scarce. Additionally, studies that have examined associations between IDS and language learning have measured learning within a single laboratory session rather than the type of long‐term storage of information necessary for word learning. In this study, 7‐ and 8‐month‐old infants' long‐term memory for words was assessed when words were spoken in IDS and adult‐directed speech (ADS). Word recognition over the long term was successful for words introduced in IDS, but not for those introduced in ADS, regardless of the register in which recognition stimuli were produced. Findings are discussed in the context of the influence of particular input styles on emergent word knowledge in prelexical infants.     

Competition for Infants' Attention: The Interactive Influence of Attentional State and Stimulus Characteristics

The interactive effects of stimulus characteristics and attentional state on infants' distraction latency were studied. As 7‐month‐old infants explored initial stimuli that were composed of either a single nonmoving component or multiple moving components, one of several types of distractors was presented in the periphery. Infants' distraction latencies (the amount of time they took to turn from the initial stimulus to the distractor) varied as a function of the interaction between the infants' attentional state at distractor onset and the characteristics of the stimuli. Variations in the visual characteristics of the distractor stimulus (solid rectangle vs. checkerboard) had a larger effect on distraction latency when infants were in a focused attentional state than when they were in a casual attentional state. Similarly, variations in the auditory characteristic of the distractor stimulus (1 intermittent tone vs. 2 alternating tones) had a larger effect when infants were engaged in a focused attentional state toward the multicomponent toys. Thus, infants' distractibility in this context reflects an interaction between the infants' attentional state and the competition between external stimuli for their attentional focus.     

Anticipatory Eye Movements Reveal Infants' Auditory and Visual Categories

We introduce a new paradigm for the assessment of auditory and visual categories in 6‐month‐old infants using a 2‐alternative anticipatory eye‐movement response. Infants were trained by 2 different methods to anticipate the location of a visual reinforcer at 1 of 2 spatial locations (right or left) based on the identity of 2 cuing stimuli. After a training phase, infants were presented with a series of generalization trials in which novel (untrained) stimuli served as the cue to the anticipatory eye movement. Four experiments illustrated that infants can learn the 2‐choice discriminative response during training. Infants also showed anticipatory eye movements to novel stimuli, indicating sensitivity to variations along a variety of stimulus dimensions (e.g., color, shape, orientation, spatial frequency, pitch, and duration). In addition, the paradigm can be used to assess categorization in individual infants, thereby revealing the stimulus dimensions to which infants naturally attend.     

An Eye Tracking Investigation of Color–Location Binding in Infants' Visual Short‐Term Memory

Two experiments examined 8‐ and 10‐month‐old infants' (N = 71) binding of object identity (color) and location information in visual short‐term memory (VSTM) using a one‐shot change detection task. Building on previous work using the simultaneous streams change detection task, we confirmed that 8‐ and 10‐month‐old infants are sensitive to changes in binding between identity and location in VSTM. Further, we demonstrated that infants recognize specifically what changed in these events. Thus, infants' VSTM for binding is robust and can be observed in different procedures and with different stimuli.     

Infants' ERP Responses to Novel and Familiar Stimuli Change Over Time: Implications for Novelty Detection and Memory

Detection of novelty is an important cognitive ability early in development, when infants must learn a great deal about their world. Work with adults has identified networks of brain areas involved in novelty detection; this study investigated electrophysiological correlates of detection of novelty and recognition of familiarity in 9‐month‐old infants, using event‐related potentials (ERPs). Infants were familiarized with an event in the laboratory, then ERPs were recorded as they viewed repeated presentations of pictures of this familiar event and a novel event, along with single presentations of 30 trial‐unique events. A middle‐latency negative component was sensitive to degree of novelty, differing in amplitude and latency by stimulus condition and across repeated presentations. Long‐latency slow‐wave activity also related to stimulus condition. Findings have implications for our understanding of infants' detection of novel information and the processes that render the novel familiar.     

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.     

Infant‐Directed Prosody Helps Infants Map Sounds to Meanings

Adults typically use an exaggerated, distinctive speaking style when addressing infants. However, the effects of infant‐directed (ID) speech on infants' learning are not yet well understood. This research investigates how ID speech affects how infants perform a key function in language acquisition, associating the sounds of words with their meanings. Seventeen‐month‐old infants were presented with two label‐object pairs in a habituation‐based word learning task. In Experiment 1, the labels were produced in adult‐directed (AD) speech. In Experiment 2, the labels were produced in ID prosody; they had higher pitch, greater pitch variation, and longer durations than the AD labels. We found that infants failed to learn the labels in AD speech, but succeeded in learning the same labels when they were produced in ID speech. Experiment 3 investigated the role of variability in learning from ID speech. When the labels were presented in ID prosody with no variation across tokens, infants failed to learn them. Our findings indicate that ID prosody can affect how readily infants map sounds to meanings and that the variability in prosody that is characteristic of ID speech may play a key role in its effect on learning new words.     

Four‐Month‐Olds' Discrimination of Voice Changes in Multimodal Displays as a Function of Discrimination Protocol

Past studies have found equivocal support for the ability of young infants to discriminate infant‐directed (ID) speech information in the presence of auditory‐only versus auditory + visual displays (faces + voices). Generally, younger infants appear to have more difficulty discriminating a change in the vocal properties of ID speech when they are accompanied by faces. Forty 4‐month‐old infants were tested using either an infant‐controlled habituation procedure (Experiment 1) or a fixed‐trial habituation procedure (Experiment 2). The prediction was that the infant‐controlled habituation procedure would be a more sensitive measure of infant attention to complex displays. The results indicated that 4‐month‐old infants discriminated voice changes in dynamic face + voice displays depending on the order in which they were viewed during the infant‐controlled habituation procedure. In contrast, no evidence of discrimination was found in the fixed‐trial procedure. The findings suggest that the selection of experimental methodology plays a significant role in the empirical observations of infant perceptual abilities.     

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.     

Is a Bird an Apple? The Effect of Speaker Labeling Accuracy on Infants' Word Learning,Imitation, and Helping Behaviors

This study examined infants' sensitivity to a speaker's verbal accuracy and whether the reliability of the speaker had an effect on their selective trust. Forty‐nine 18‐month‐old infants were exposed to a speaker who either accurately or inaccurately labeled familiar objects. Subsequently, the speaker administered a series of tasks in which infants had an opportunity to: learn a novel word, imitate the speaker's “irrational” actions, and help the speaker obtain an out‐of‐reach object. In contrast to infants in the accurate (reliable) condition, those in the inaccurate (unreliable) condition performed more poorly on a word‐learning task and were less likely to imitate. All infants demonstrated high rates of instrumental helping behavior. These results are the first to demonstrate that infants as young as 18 months of age cannot only detect a speaker's verbal inaccuracy but also use this information to attenuate their word recognition and learning of novel actions.     

Sensitivity to Social Contingency From Mothers and Strangers in 2‐, 4‐, and 6‐Month‐Old Infants

Infants' sensitivity to changes in social contingency was investigated by presenting 2‐, 4‐, and 6‐month‐old infants with 3 episodes of social interaction from mothers and strangers: 2 contingent interactions and 1 noncontingent replay. Three orders were presented: (a) contingent, noncontingent, contingent; (b) contingent, contingent, noncontingent; and (c) noncontingent, contingent, contingent. Contingency and carryover effects were shown to both mothers and strangers in the different orders of presentation. Infants were more visually attentive to contingent interactions than to the noncontingent replay when contingent interactions occurred prior to the replay, and the infants' level of attention to the noncontingent replay carried over to subsequent contingent interactions. The 4‐ and 6‐month‐old infants showed contingency and carryover effects by their visual attention and smiling. Examination of effect sizes for attention suggests 2‐month‐old infants may be beginning to show the effects. Reasons for age changes in sensitivity to social contingency are discussed.     

Bimodal Dynamics of Faces and Voices Influence Older Infants' Perception of Emotion

Given the importance of infants' perception of bimodal speech for emerging language and emotion development, this study used eye‐tracking technology to examine infants' attention to face+voice displays differing by emotion (fear, sad, happy) and visual stimulus (dynamic versus static). Peripheral distracters were presented to measure attention disengagement. It was predicted that infants would look longer at and disengage more slowly from dynamic bimodal emotion displays, especially when viewing dynamic fear. However, the results from twenty‐two 10‐month‐olds found significantly greater attention on dynamic versus static trials, independent of emotion. Interestingly, infants looked equally to mouth and eye regions of speakers' faces except when viewing/hearing dynamic fear; in this case, they fixated more on the speakers' mouth region. Average latencies to distracters were longer on dynamic compared to static bimodal stimuli, but not differentiated by emotion. Thus, infants' attention was enhanced (in terms of both elicitation and maintenance) by dynamic, bimodal emotion displays. Results are compared to conflicting findings using static emotion displays, with suggestions for future research using more ecologically relevant dynamic, multimodal displays to gain a richer understanding of infants' processing of emotion.