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Biomedical subjects

A N Meltzoff

Publications and source records attributed to A N Meltzoff.

At least 19 recordsLinked to original sources
PubMed2005

Brain activation during face perception: evidence of a developmental change.

Behavioral studies suggest that children under age 10 process faces using a piecemeal strategy based on individual distinctive facial features, whereas older children use a configural strategy based on the spatial relations among the face's features. The purpose of this study was to determine whether activation of the fusiform gyrus, which is involved in face processing in adults, is greater during face processing in older children (12-14 years) than in younger children (8-10 years). Functional MRI scans were obtained while children viewed faces and houses. A developmental change was observed: Older children, but not younger children, showed significantly more activation in bilateral fusiform gyri for faces than for houses. Activation in the fusiform gyrus correlated significantly with age and with a behavioral measure of configural face processing. Regions believed to be involved in processing basic facial features were activated in both younger and older children. Some evidence was also observed for greater activation for houses versus faces for the older children than for the younger children, suggesting that processing of these two stimulus types becomes more differentiated as children age. The current results provide biological insight into changes in visual processing of faces that occur with normal development.

Adolescent↗
PubMed2002

A PET exploration of the neural mechanisms involved in reciprocal imitation.

Imitation is a natural mechanism involving perception-action coupling which plays a central role in the development of understanding that other people, like the self, are mental agents. PET was used to examine the hemodynamic changes occurring in a reciprocal imitation paradigm. Eighteen subjects (a) imitated the actions of the experimenter, (b) had their actions imitated by the experimenter, (c) freely produced actions, or (d) freely produced actions while watching different actions made by the experimenter. In a baseline condition, subjects simply watched the experimenter's actions. Specific increases were detected in the left STS and in the inferior parietal cortex in conditions involving imitation. The left inferior parietal is specifically involved in producing imitation, whereas the right homologous region is more activated when one's own actions are imitated by another person. This pattern of results suggests that these regions play a specific role in distinguishing internally produced actions from those generated by others.

Adult↗
PubMed2001

How the brain perceives causality: an event-related fMRI study.

Detection of the causal relationships between events is fundamental for understanding the world around us. We report an event-related fMRI study designed to investigate how the human brain processes the perception of mechanical causality. Subjects were presented with mechanically causal events (in which a ball collides with and causes movement of another ball) and non-causal events (in which no contact is made between the balls). There was a significantly higher level of activation of V5/MT/MST bilaterally, the superior temporal sulcus bilaterally and the left intraparietal sulcus to causal relative to non-causal events. Directing attention to the causal nature of the stimuli had no significant effect on the neural processing of the causal events. These results support theories of causality suggesting that the perception of elementary mechanical causality events is automatically processed by the visual system.

Adult↗
PubMed1998

Children with autism fail to orient to naturally occurring social stimuli.

Children with autism were compared to developmentally matched children with Down syndrome or typical development in terms of their ability to visually orient to two social stimuli (name called, hands clapping) and two nonsocial stimuli (rattle, musical jack-in-the-box), and in terms of their ability to share attention (following another's gaze or point). It was found that, compared to children with Down syndrome or typical development, children with autism more frequently failed to orient to all stimuli, and that this failure was much more extreme for social stimuli. Children with autism who oriented to social stimuli took longer to do so compared to the other two groups of children. Children with autism also exhibited impairments in shared attention. Moreover, for both children with autism and Down syndrome, correlational analyses revealed a relation between shared attention performance and the ability to orient to social stimuli, but no relation between shared attention performance and the ability to orient to nonsocial stimuli. Results suggest that social orienting impairments may contribute to difficulties in shared attention found in autism.

Attention↗
PubMed1998

Neuropsychological correlates of early symptoms of autism.

Both the medial temporal lobe and dorsolateral prefrontal cortex have been implicated in autism. In the present study, performance on two neuropsychological tasks--one tapping the medial temporal lobe and related limbic structures, and another tapping the dorsolateral prefrontal cortex--was examined in relation to performance on tasks assessing autistic symptoms in young children with autism, and developmentally matched groups of children with Down syndrome or typical development. Autistic symptoms included orienting to social stimuli, immediate and deferred motor imitation, shared attention, responses to emotional stimuli, and symbolic play. Compared with children with Down syndrome and typically developing children, children with autism performed significantly worse on both the medial temporal lobe and dorsolateral prefrontal tasks, and on tasks assessing symptoms domains. For children with autism, the severity of autistic symptoms was strongly and consistently correlated with performance on the medial temporal lobe task, but not the dorsolateral prefrontal task. The hypothesis that autism is related to dysfunction of the medial temporal lobe and related limbic structures, such as the orbital prefrontal cortex, is discussed.

Age Factors↗
PubMed1996

Infant vocalizations in response to speech: vocal imitation and developmental change.

Infants' development of speech begins with a language-universal pattern of production that eventually becomes language specific. One mechanism contributing to this change is vocal imitation. The present study was undertaken to examine developmental change in infants' vocalizations in response to adults' vowels at 12, 16, and 20 weeks of age and test for vocal imitation. Two methodological aspects of the experiment are noteworthy: (a) three different vowel stimuli (/a/, /i/, and /u/) were videotaped and presented to infants by machine so that the adult model could not artifactually influence infant utterances, and (b) infants' vocalizations were analyzed both physically, using computerized spectrographic techniques, and perceptually by trained phoneticians who transcribed the utterances. The spectrographic analyses revealed a developmental change in the production of vowels. Infants' vowel categories become more separated in vowel space from 12 to 20 weeks of age. Moreover, vocal imitation was documented, infants listening to a particular vowel produced vocalizations resembling that vowel. A hypothesis is advanced extending Kuhl's native language magnet (NLM) model to encompass infants' speech production. It is hypothesized that infants listening to ambient language store perceptually derived representations of the speech sounds they hear which in turn serve as targets for the production of speech utterances. NLM unifies previous findings on the effects of ambient language experience on infants' speech perception and the findings reported here that short-term laboratory experience with speech is sufficient to influence infants' speech production.

Age Factors↗
PubMed1995

What infant memory tells us about infantile amnesia: long-term recall and deferred imitation.

Long-term recall memory was assessed using a nonverbal method requiring subjects to reenact a past event from memory (deferred imitation). A large sample of infants (N = 192), evenly divided between 14- and 16-months old, was tested across two experiments. A delay of 2 months was used in Experiment 1 and a delay of 4 months in Experiment 2. In both experiments two treatment groups were used. In one treatment group, motor practice (immediate imitation) was allowed before the delay was imposed; in the other group, subjects were prevented from motor practice before the delay. Age-matched control groups were used to assess the spontaneous production of the target acts in the absence of exposure to the model in both experiments. The results demonstrated significant deferred imitation for both treatment groups at both delay intervals, and moreover showed that infants retained and imitated multiple acts. These findings suggest that infants have a nonverbal declarative memory system that supports the recall of past events across long-term delays. The implications of these findings for the multiple memory system debate in cognitive science and neuroscience and for theories of infantile amnesia are considered.

Attention↗
PubMed1991

Cross-modal speech perception in adults and infants using nonspeech auditory stimuli.

Adults and infants were tested for the capacity to detect correspondences between nonspeech sounds and real vowels. The /i/ and /a/ vowels were presented in 3 different ways: auditory speech, silent visual faces articulating the vowels, or mentally imagined vowels. The nonspeech sounds were either pure tones or 3-tone complexes that isolated a single feature of the vowel without allowing the vowel to be identified. Adults perceived an orderly relation between the nonspeech sounds and vowels. They matched high-pitched nonspeech sounds to /i/ vowels and low-pitched nonspeech sounds to /a/ vowels. In contrast, infants could not match nonspeech sounds to the visually presented vowels. Infants' detection of correspondence between auditory and visual speech appears to require the whole speech signal; with development, an isolated feature of the vowel is sufficient for detection of the cross-modal correspondence.

Adult↗
PubMed1991

Integrating speech information across talkers, gender, and sensory modality: female faces and male voices in the McGurk effect.

Studies of the McGurk effect have shown that when discrepant phonetic information is delivered to the auditory and visual modalities, the information is combined into a new percept not originally presented to either modality. In typical experiments, the auditory and visual speech signals are generated by the same talker. The present experiment examined whether a discrepancy in the gender of the talker between the auditory and visual signals would influence the magnitude of the McGurk effect. A male talker's voice was dubbed onto a videotape containing a female talker's face, and vice versa. The gender-incongruent videotapes were compared with gender-congruent videotapes, in which a male talker's voice was dubbed onto a male face and a female talker's voice was dubbed onto a female face. Even though there was a clear incompatibility in talker characteristics between the auditory and visual signals on the incongruent videotapes, the resulting magnitude of the McGurk effect was not significantly different for the incongruent as opposed to the congruent videotapes. The results indicate that the mechanism for integrating speech information from the auditory and the visual modalities is not disrupted by a gender incompatibility even when it is perceptually apparent. The findings are compatible with the theoretical notion that information about voice characteristics of the talker is extracted and used to normalize the speech signal at an early stage of phonetic processing, prior to the integration of the auditory and the visual information.

Adult↗
PubMed1990

Towards a developmental cognitive science. The implications of cross-modal matching and imitation for the development of representation and memory in infancy.

This chapter began with a query about whether there was any content to an enterprise called "developmental cognitive science," and if so, whether the findings could inform work in adult cognition and neuropsychology. Both questions can now be answered in the affirmative. Evidence has been marshaled from infant studies concerning five topics of enduring interest in the cognitive and neuro-sciences: cross-modal integration, imitation, the coordination of perception and action, memory, and representation. The data show that young human infants can detect equivalences between information picked up by different sensory modalities. This was demonstrated both in tactual-visual perception of objects and auditory-visual perception of speech. Results also show that perception and production are intertwined literally from the earliest phases of infancy, with 4-month-olds demonstrating vocal imitation and newborns reproducing elementary gestures they saw an adult perform. There seems to be a transparency between the perceptual and motor systems, and it is conceivable that they may draw on the same internal code. Infants' proclivity to imitate was used to investigate early memory. It was found that young infants were not constrained to immediate mimicry, but could imitate after significant delays. The findings support the inference that infants, perhaps as early as birth, have a functioning memory system that cannot be reduced to "habit formation" or an exclusively "procedural memory." It was proposed instead that there is a kernel of some higher level memory system right from the earliest phases of human infancy. This does not imply that there is no development in the representational world of infants. Data were reviewed suggesting that there is a watershed transformation in childhood cognition at about 18 months of age. However, this is not a change from a stage in which there was a purely sensorimotor or habit-based system. Rather the development was characterized as a shift from using empirical or experience-based representations to using hypothetical representations, which concern possible realities. This developmental shift allows children to project into the future "what must be" and deduce from the past "what must have been," in advance of, and sometimes in the absence of, strictly perceptual evidence. This capacity provides the underpinnings for the conduct of science itself. Its origins are to be found in infancy.

Aging↗
PubMed1988

Imitation of televised models by infants.

Studies indicate that infants in our culture are exposed to significant amounts of TV, often as a baby-sitting strategy by busy caretakers. The question arises whether TV viewing merely presents infants with a salient collection of moving patterns or whether they will readily pick up information depicted in this 2-D representation and incorporate it into their own behavior. Can infants "understand" the content of television enough to govern their real-world behavior accordingly? One way to explore this question is to present a model via television for infants to imitate. Infants' ability to imitate TV models was explored at 2 ages, 14 and 24 months, under conditions of immediate and deferred imitation. In deferred imitation, infants were exposed to a TV depiction of an adult manipulating a novel toy in a particular way but were not presented with the real toy until the next day. The results showed significant imitation at both ages, and furthermore showed that even the youngest group imitated after the 24-hour delay. The finding of deferred imitation of TV models has social and policy implications, because it suggests that TV viewing in the home could potentially affect infant behavior and development more than heretofore contemplated. The results also add to a growing body of literature on prelinguistic representational capacities. They do so in the dual sense of showing that infants can relate 2-D representations to their own actions on real objects in 3-D space, and moreover that the information picked up through TV can be internally represented over lengthy delays before it is used to guide the real-world action.

Child, Preschool↗
PubMed1988

Infant imitation and memory: nine-month-olds in immediate and deferred tests.

The ability of 9-month-old infants to imitate simple actions with novel objects was investigated. Both immediate and deferred imitation were tested, the latter by interposing a 24-hour delay between the stimulus-presentation and response periods. The results provide evidence for both immediate and deferred imitation; moreover, imitative responding was not significantly dampened by the 24-hour delay. The findings demonstrate that there exists some underlying capacity for deferring imitation of certain acts well under 1 year of age, and thus that this ability does not develop in a stagelike step function at about 18-24 months as commonly predicted. These findings also show that imitation in early infancy can span wide enough delays to be of potential service in social development; actions on novel objects that are observed one day can be stored by the child and repeated the next day. The study of deferred imitation provides a largely untapped method for investigating the nature and development of recall memory in the preverbal child.

Humans↗
PubMed1983

Newborn infants imitate adult facial gestures.

Newborn infants ranging in age from 0.7 to 71 hours old were tested for their ability to imitate 2 adult facial gestures: mouth opening and tongue protrusion. Each subject acted as his or her own control in a repeated-measures design counterbalanced for order of stimulus presentation. The subjects were tested in low illumination using infrared-sensitive video equipment. The videotaped records were scored by an observer who was uninformed about the gesture shown to the infants. Both frequency and duration of neonatal mouth openings and tongue protrusions were tallied. The results showed that newborn infants can imitate both adult displays. 3 possible mechanisms underlying this early imitative behavior are suggested: instrumental or associative learning, innate releasing mechanisms, and active intermodal matching. It is argued that the data favor the third account.

Facial Expression↗
PubMed1982

The bimodal perception of speech in infancy.

Infants 18 to 20 weeks old recognize the correspondence between auditorially and visually presented speech sounds, and the spectral information contained in the sounds is critical to the detection of these correspondences. Some infants imitated the sounds presented during the experiment. Both the ability to detect auditory-visual correspondences and the tendency to imitate may reflect the infant's knowledge of the relationship between audition and articulation.

Humans↗