Questions concerning longitudinal stability and multi-method consistency are critical to temperament research. Latent State-Trait (LST) analyses address these directly, and were utilized in this study. Thus, our primary objective was to apply LST analyses in a temperament context, using longitudinal and multi-method data to determine the amount of…

Five-month-old infants' vocalization when alone was investigated. Several researchers have reported observing that young infants vocalize in comfortable states without any response from others. As is implied by episodic reports in previous studies, it is possible that infants vocalize to play with their own vocal sound. Producing and listening to…