Manual exploratory behaviors during object interaction that form the basis of tool use behavior, are mostly qualitatively characterized in terms of their frequency and duration of occurrence. To fully understand their functional and clinical significance, quantitative movement characterization is needed alongside their qualitative analysis.…

Fifty-one 23-to-55-month-old-infants faced two apparatuses that required the use of a rigid (box apparatus) or flexible (hose apparatus) stick-like tool to retrieve a toy stuck inside. Before attempting the extraction, however, they had to pick the only one tool (of three) on display that had the appropriate rigidity/flexibility to be effective.…