Developmental Relationships Between Early Vocabulary Acquisition, Joint Attention and Parental Supportive Behaviors

In late infancy and early toddlerhood, joint attention ability is widely recognized as a crucial foundation for children's vocabulary development, though the exact nature of its contribution remains debated. This study investigates associations between joint attention and subsequent vocabulary development, as well as the possible moderating role of supportive parental behaviors. Seventy children and their families participated in this longitudinal study, which began when the children were 10 months of age. Parents completed the Swedish Communicative Development Inventory (CDI) at four age points (10, 12, 18, and 24 months) to assess receptive and expressive vocabulary growth. Children participated in lab-based assessment of joint attention abilities at 10, 12, and 18 months. Additionally, at 10 and 12 months, parent-child dyads participated in two semi-structured lab assessments to evaluate the quality of parental supportive behaviors during interactions with their child. Primary analysis showed no significant effects of joint attention on subsequent receptive and expressive vocabulary. However, a significant interaction was found between a child's ability to respond to joint attention cues and parental supportive behaviors on receptive vocabulary. These findings indicate that parental supportive behaviors play a crucial role in promoting the development of children's receptive vocabulary.