Mu desynchronization is the attenuation of EEG power in the alpha frequency range recorded over central scalp locations thought to reflect motor cortex activation. Mu desynchronization during observation of an action is believed to reflect mirroring system activation in humans. However, this notion has recently been questioned because, among other reasons, the potential contamination of mu rhythm and occipital alpha activity induced by attention processes following presentation of visual stimuli in observation conditions. This study examined the validity of mu desynchronization as a measure of mirroring system activation in infants and further investigated the pattern of functional connectivity between the central and occipital regions during execution and observation of movement. EEG was recorded while 46 9-monthold infants executed grasping actions and observed an experimenter grasping. Current source density (CSD) was applied to EEG data and, time-frequency and connectivity analyses were performed in CSD transformed data. Mu desynchronization was evident over central regions during both execution and observation of movements. Independent alpha desynchronization over occipital region was also present in both conditions. The connectivity analyses revealed that central-occipital areas were functionally more connected compared to other areas of the brain during observation of movements. Collectively, the results demonstrate the validity of mu desynchronization as an index of infant mirroring system activity and support the proposal of a functional connection between distinct mirroring and attention processes during observation of action.

In infancy, use of gesture and the ability to engage in joint attention with others both predict later language development. Conceptually, gesture and joint attention abilities may reflect a similar underlying social communicative skill. However, these abilities are often studied separately. Despite the fact that gesture is often used in episodes of joint attention, little is known about the degree to which measures of gesture use and joint attention ability are associated with one another or how they similarly, or differentially, predict children's language abilities. Participants in the current study were 53 infants. At 12-months, multiple measures of infants' gesture use were gleaned from a free-play interaction with a parent. Infants' responding to and initiating joint attention were measured via the Early Social-Communicative Scales (ESCS, Mundy et al., 2003). Infants' expressive and receptive language was measured at 24-months with the Mullen Scales of Early Learning (Mullen, 1995). A factor analysis including gesture and joint attention measures indicated that at 12-months joint attention, particularly responding to joint attention, reflects a similar underlying construct with infant gesture use, yet they uniquely predict later language ability.

Background: Children with the temperament of behavioral inhibition (BI) face increased risk for social anxiety. However, not all children with BI develop anxiety symptoms. Inhibitory control (IC) has been suggested as a moderator of the pathway between BI and social anxiety. This study uses longitudinal data to characterize development of IC and tests the hypothesis that IC moderates associations between early BI and later social anxiety symptoms. Methods: Children completed a Go/Nogo task at ages 5, 7, and 10 years as part of a longitudinal study of BI (measured at 2-3 years) and social anxiety symptoms (measured at 12 years). To assess IC development, response strategy (criterion) and inhibitory performance (d 0 ) were characterized using signal detection theory. Latent growth models were used to characterize the development of IC and examine relations among BI, IC parameters, and social anxiety symptoms. Results: IC response strategy did not change between 5 and 10 years of age, whereas IC performance improved over time. BI scores in toddlerhood predicted neither initial levels (intercept) nor changes (slope) in IC response strategy or IC performance. However, between ages 5 and 10, rate of change in IC performance, but not response strategy, moderated relations between BI and later parent-reported social anxiety symptoms. Specifically, greater age-related improvements in IC performance predicted higher levels of social anxiety in high BI children. Conclusions: IC development in childhood occurs independent of BI levels. However, rapid increases in IC performance moderate risk for social anxiety symptoms in children with BI. Implications for theory and practice are discussed.

Fathers’ child-directed speech across two contexts was examined. Father–child dyads from sixty-nine low-income families were videotaped interacting during book reading and toy play when children were 2;0. Fathers used more diverse vocabulary and asked more questions during book reading while their mean length of utterance was longer during toy play. Variation in these specific characteristics of fathers’ speech that differed across contexts was also positively associated with child vocabulary skill measured on the MacArthur-Bates Communicative Development Inventory. Results are discussed in terms of how different contexts elicit specific qualities of child-directed speech that may promote language use and development.

Background: Children with Behavioral Inhibition (BI) temperament face increased social anxiety risk. However, not all children with BI develop anxiety symptoms. Inhibitory control (IC) has been suggested as a moderator of the pathway between BI and social anxiety. The current study uses longitudinal data to characterize development of IC and tests the hypothesis that IC moderates associations between early BI and later social anxiety symptoms. Methods: Children completed a Go/Nogo task at ages 5, 7, and 9 years as part of a longitudinal study of BI (measured at 2-3 years) and social anxiety symptoms (measured at 12 years). To assess IC development, response strategy (criterion) and inhibitory performance (d’) were characterized using signal detection theory. Latent growth models were used to characterize the development of IC and examine relations among BI, IC parameters, and social anxiety symptoms. Results: IC response strategy did not change between 5 and 9 years of age, whereas IC performance improved over time. BI scores in toddlerhood predicted neither initial levels (intercept) nor changes (slope) in IC response strategy or IC performance. However, between ages 5 and 9, rate of change in IC performance, but not response strategy, moderated relations between BI and later parent-reported social anxiety symptoms. Specifically, greater age-related improvements in IC performance predicted higher levels of social anxiety in high BI children.Conclusions: IC development in childhood occurs independent of BI levels. However, rapid IC development moderates risk for social anxiety symptoms in children with BI. Implications for theory and practice are discussed.