Observational Learning and Generalization in Infant Grasps of Novel Tools

Tool use is a critical skill acquired in infancy. Here, we tested whether infants could learn how to grasp a tool from observing an adult model and whether this learning generalized to a new task and to increasingly dissimilar tools. Infants between 13 and 19 months of age (N = 75; M_age = 16.31 months; SD_age = 1.73 months; 36 girls) observed an adult grasp a spatula-shaped tool by the narrow end, wide end, or both ends in alternation to push pom-poms through a tube during a modeling phase. Infants in a control condition observed an adult pour pom-poms from one large container into another. During a test phase, infants were given an opportunity to use the same tool, a tool that differed only in color, and a tool that differed in both color and shape to activate one of two puzzle boxes. Each puzzle box required one specific grip of the tool for activation (e.g., gripping the narrow, handle end to insert the wide, flat end into a thin slot on the box; gripping the wide, flat end to insert the narrow, handle end into a small hole on the box). Before the adult demonstration, infants spent more time grasping the tool by the narrow end (akin to grasping a spoon by the handle rather than the scooping end). After the demonstration, infants used more wide end grasps for the appropriate puzzle box if they observed the adult grasp the tool by the wide end during modeling. Overall, infants were able to transfer their knowledge to the tool that differed in color, but they were less likely to activate their puzzle box with the tool that differed in both color and shape. Findings indicate that 13- to 19-month-old infants can learn a new use of a tool from observing an adult demonstration, but generalization is relatively narrow and limited.