The roles of observation and manipulation in learning to use a tool

We investigated how repeated, five-minute familiarization sessions occurring once a week over a 6-week period influenced infants’ knowledge about the functional properties of a rake-like tool and their ability to use it for retrieving an out of reach object by 16 months of age. We found that infants, who were not allowed to touch the rake, but only to observe an adult retrieve an object with it, improved their performance. On the other hand, infants who were allowed to manually manipulate the rake and touch and move other objects with it did not improve their performance. The results, which were replicated in a string-pulling task, suggest that, although both motor and cognitive limitations affect performance, it is rather cognitive limitations that prevent infants from understanding the functional properties of the tool and from succeeding in such tool-use tasks. Furthermore, infants can overcome these cognitive limitations with only a few, brief demonstrations spaced over several weeks.