Developmental studies have revealed that preschool-aged children believe that an agent’s internal properties are more important than its external properties for determining its identity over time. The current study examined the developmental origins of this understanding using a manual-search individuation task with 13-month-old infants. Subjects observed semi-transparent objects that looked and behaved like animate agents placed into box that they could reach but not see into. Across trials infants observed objects with either the same- or different-colored insides placed into the box. We found that infants used internal property differences more than external property differences to determine how many agents were involved in the event. A second experiment confirmed that this effect was specific to the domain of animate entities. These results suggest that infants are biased to see an agent’s ‘insides’ as more important for determining its identity over time than its outside properties.

Newborn infants with differential patterns of fetal growth, as determined by their weight-for-length, typically display behaviors which have been conceptualized as reflecting the integrity of the infant's behavioral organization. The newborn infant's sucking is one behavior that has been hypothesized to both reflect the effects of previous experiences on behavioral organization and affect the infant's future behavioral development. In particular, the infant's pattern of sucking activity may not only reflect the integrity of the infant's nervous system, it may also alter the temporal organization of the infant's behavioral state and motor activity by increasing behavioral quiescence. The purpose of this study was to compare the sucking activity of underweight-for-length (N = 30) and average-weight-for-length (N = 30) infants and its effects on behavioral state and motor activity. Fifteen low-PI and 15 average-PI infants were randomly assigned to each of two experimental conditions. / Master of Science

The purpose of this study was to conduct a qualitative case study using secondary data on four mothers with premature infants in a home visitation intervention group. Three data points were collected on each mother and infant: the health of the infant, the quality of attachment as seen in play interactions, and maternal life circumstances such as depression, social support and use of community resources. The data was looked at prenatally up until the infants were 15 months old. The results indicated that all four infants were relatively healthy across the first year of their lives. Three out of the four mothers had a secure attachment with their premature infants at 12 months of age and one mother was at risk for an insecure attachment. All four mothers demonstrated some positive play interactions; however, one mother in particular demonstrated low involvement. Of the four mothers, one was highly depressed, and the other three mothers were minimally to moderately depressed. The four mothers were also in a marital or partner relationship, and all reported satisfaction in their support systems as well as very similar uses of community resources. The results of this study can be used to assist Home Visitors in understanding the need to help mothers improve their interactions with their premature infants and to encourage the Home Visitors to refer the mothers who show any signs of depression.

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Past research has found that infants between 1- and 4-months of age prefer extremely slow infant-directed (ID) speech to normal ID speech. Given that previous studies have paired the speech with a visual display, it was thought that perhaps the characteristics of the visual display affected infant preferences for rate of speaking. The present investigation was an attempt to explore this possibility. In Experiment 1, 3- to 4-month old infants were presented with ID-normal and ID-slow speech samples paired with displays of higher and lower complexity. Here, the results showed that infants preferred ID-slow to ID-normal speech regardless of display complexity. The purpose of Experiment 2 was to determine whether infant preference for speaking rate could be affected by structural differences in the visual displays. The same ID-normal and ID-slow speech samples used in Experiment 1 were paired with visual displays that either had components in a face-like or scrambled arrangement. The results of Experiment 2 showed that infants preferred the face-like display over the scrambled display regardless of what speech type was presented (i.e., there was not preference for ID-slow speech). The results of the study as a whole indicate that young infants prefer ID-slow to ID-normal speech, but that the presence of a face-like image may overshadow this preference. The study as a whole indicates that assertions about the power of ID-slow speech, as well as any auditory event in general, should not fail to address the potential influence of other sensory factors, particularly visual. / Ph. D.

Recent investigations into infants' intersensory perception suggest a specific developmental pattern for infants' attention to visible and auditory attributes of dynamic human faces. This work has proposed that infants' perception seems to progress along a sensory continuum: beginning with multimodal sensory cues (e.g., auditory and visual), then visual-cues alone, and finally auditory-cues alone. Additionally, research has proposed that amodal or invariant sensory information directs infants' attention to specific redundant aspects in the surrounding environment (e.g., temporal synchronicity). The current research attempted to clarify the potential methodological confounds contained in previous investigations into infant intersensory development by contrasting infant behavior within fixed trial and infant-controlled habituation procedures. Moreover, the current research examined infants' attention to auditory manipulations within multimodal displays when redundant sensory information (synchronicity) was or was not available. In Experiment 1, 4-month-old infants were habituated to complex audiovisual displays of a male or female face within an infant controlled habituation procedure, and then tested for response recovery to a change in voice. For half the infants, the change in voice maintained synchronicity with the face, and for the other half, it did not. The results showed significant response recovery (i.e., dishabituation) to the change in voice regardless of the synchronicity condition. In Experiment 2, 4-month-old infants received the same face+voice test recordings used in Experiment 1, but now within a fixed trial habituation procedure. Again, synchronicity was manipulated across groups of infants. In contrast to Experiment 1, the infants in the fixed-trial experiment failed to show evidence of voice discrimination. These results suggest that infant controlled procedures may be more sensitive to infant attention, especially in terms of complex social displays. In addition, synchronicity appeared to be unnecessary in terms of infants' ability to detect vocal differences across multimodal displays. In sum, these results highlight the importance of research methodology (e.g., infant control) and overall stimulus complexity (e.g., discrete vs. complex) involving studies of infants' intersensory development. / Ph. D.