Performance during Object Retrieval Tasks in Typical Infants and Infants with DS
In this study, we are extending our current knowledge about object play in children with DS to a specific functional skill, object retrieval . Object retrieval requires means-ends exploration, i.e., planning and executing different strategies as a means to achieve an end goal of toy retrieval, and has been extensively studied in the typical population using tasks such as retrieving an object from a concealed container or pulling a cloth to retrieve a toy located at the end of the cloth (Piaget, 1953; Willatts, 1999). In TD infants, the ability to successfully retrieve objects usually emerges during the end of first year, however, infants continue to refine this skill in the second year of life. Bruner (1970) examined the development of object retrieval during the first 2 years of life and indicated that infants younger than 6-8 months old were unsuccessful in the task. Older infants between 9-17 months were successful but infants seem to refine this skill with increasing age such that infants between 9 and 11 months used unimanual strategies, infants between 12 and 14 months used bimanual strategies, and infants between 15 and 17 months used complex (more refined) bimanual strategies to retrieve the toy (Bruner, 1970). Means-ends exploration and object retrieval skills depend on the motor (Bojczyk & Corbetta, 2004), perceptual (Babik et al., 2019), and cognitive skills of children (Willats, 1999; Sommerville & Woodward, 2005). Furthermore, means-ends exploration is a crucial development skill and is closely associated with the development of goal-directed behaviors, problem solving skills, and intentionality (Willats, 1999; Babik et al., 2019).
In contrast to the TD infants, there is a relative dearth of studies on the development of object retrieval skills in infants and children with DS (Schworer et al., 2020; Fidler, Hepburn, et al., 2005). When compared to TD controls, 4- to 12-months old with DS took longer to execute strategies such as pulling a cloth and grasping a toy while trying to retrieve a toy located at the end of a 12-inch cloth (Schworer et al., 2020). Similarly, 2- to 3-year-old children with DS produced fewer effective strategies while trying to retrieve a toy/snack from a clear plexiglass box with an opening on one side (Fidler, Hepburn, et al., 2005). Furthermore, object retrieval strategies were associated with the non-verbal behaviors of children with DS, such that children with poor retrieval strategies (e.g., more reaching failures) showed fewer non-verbal behaviors in social contexts (e.g., less looking/pointing at objects and less requesting of social routines like tickling) (Fidler, Philofsky, et al., 2005). Overall, existing evidence indicates that infants and children with DS are less successful than their TD peers in means-ends exploration tasks requiring the retrieval of hidden objects.