Physiological self-regulation and information processing in infancy: cardiac vagal tone and habituation

This study investigates the role of physiological self-regulation (cardiac vagal tone) in information processing (habituation) in 81 infants. Nucleus ambiguus vagal tone (Vna, a measure of respiratory sinus arrhythmia) was used to index cardiac vagal tone. Physiological self-regulation was operationalized as the change in Vna from a baseline period of measurement to habituation. Decreases in Vna consistently related to habituation efficiency, operationalized as accumulated looking time (ALT), in all infants twice at 2 months and twice at 5 months; however, this relation was accounted for by infants who met an habituation criterion on each task. Among habituators, shorter lookers also had greater Vna suppression during habituation. Within-age and between-age suppression of vagal tone predicted ALT, but ALT did not predict suppression of vagal tone. Physiological self-regulation provided by the vagal system appears to play a role in information processing in infancy as indexed by habituation.     

Mother-Child Play: Sequential Interactions and the Relation between Maternal Beliefs and Behaviors

This investigation of mother and toddler play had 2 goals. The primary goal was to examine the types of play mothers introduce in direct response to their toddlers' play. A secondary and exploratory goal was to examine the relation between maternal knowledge about child play and actual maternal play behaviors. 50 mothers and their 21-month-old toddlers were observed at home during free play. Mother and child exploratory, nonsymbolic, and symbolic play were coded. Sequential analyses revealed that mothers adjusted their play to their children's play level by responding to their children with play that was either at the same level or at a higher level than their children's play. Furthermore, mothers who were more knowledgeable about early play development more often responded to their children's play by introducing higher level play. These findings suggest that mothers tend to play with their toddlers in ways that might promote their child's development, and that mothers with more knowledge about play development provide their children with appropriately challenging play interactions.     

Solitary and Collaborative Pretense Play in Early Childhood: Sources of Individual Variation in the Development of Representational Competence

This study evaluates sources of individual variation in child pretense play as an expression of emerging mental representation. Family sociodemographic characteristics, maternal personological characteristics, and maternal affective and cognitive play behaviors, as well as children's gender, language competence, and play, were examined simultaneously. Naturalistic child solitary play and child collaborative play with mother were videorecorded in 141 20–month-olds. Child solitary play, child-initiated and mother-initiated collaborative play with mother, and maternal demonstrations and solicitations of play were then coded into nonsymbolic and symbolic acts. Zero-order relations obtained between child play and, respectively, child gender and language, family SES, and maternal verbal intelligence, personality, physical affection, and play demonstrations and solicitations. Structural equation modeling supported the following unique predictive relations: Child language and mothers' symbolic play positively influenced child collaborative play, and child gender and mothers' verbal intelligence predicted child solitary play. Child gender and mothers' verbal intelligence and physical affection influenced mothers' play and so influenced child collaborative play indirectly. The cognitive advantages of child play and maternal influences on child play are placed in an adaptive parenting framework.     

The Value of Vocalizing: Five-Month-Old Infants Associate Their Own Noncry Vocalizations With Responses From Caregivers

The early noncry vocalizations of infants are salient social signals. Caregivers spontaneously respond to 30%–50% of these sounds, and their responsiveness to infants’ prelinguistic noncry vocalizations facilitates the development of phonology and speech. Have infants learned that their vocalizations influence the behavior of social partners? If they have, infants should show an extinction burst in vocalizing when adults temporarily stop responding to infant vocalizations. Thirty‐eight 5‐month‐olds were tested in the still‐face paradigm with an unfamiliar adult. When the adult assumed a still face, infants showed an extinction burst. Thus, 5‐month‐olds have learned the social efficacy of their vocalizations on caregivers’ behavior. Furthermore, the magnitude of 5‐month infants’ extinction bursts predicted their language comprehension at 13 months.     

Infant Temperament: Stability by Age,Gender, Birth Order,Term Status,and Socioeconomic Status

Two complementary studies focused on stability of infant temperament across the 1st year and considered infant age, gender, birth order, term status, and socioeconomic status (SES) as moderators. Study 1 consisted of 73 mothers of firstborn term girls and boys queried at 2, 5, and 13 months of age. Study 2 consisted of 335 mothers of infants of different gender, birth order, term status, and SES queried at 6 and 12 months. Consistent positive and negative affectivity factors emerged at all time points across both studies. Infant temperament proved stable and robust across gender, birth order, term status, and SES. Stability coefficients for temperament factors and scales were medium to large for shorter (< 9 months) interassessment intervals and small to medium for longer (> 10 months) intervals.     

A practical guide for the fabrication of microfluidic devices using glass and silicon

This paper describes the main protocols that are used for fabricating microfluidic devices from glass and silicon. Methods for micropatterning glass and silicon are surveyed, and their limitations are discussed. Bonding methods that can be used for joining these materials are summarized and key process parameters are indicated. The paper also outlines techniques for forming electrical connections between microfluidic devices and external circuits. A framework is proposed for the synthesis of a complete glass/silicon device fabrication flow.