Human hammering with an elastic hammer restricted to 1-DOF with different stiffnesses

The experiment aims at studying human use of flexible tools. The research question is how intuitive it is for humans to use a flexible tool in the optimal way. The task chosen for that is to hammer with a flexible hammer (115 g). The experiment setup is a hammer mounted on an axis with a changeable flexible extension. A target is mounted in front of the hammer such that it can be hit by moving the hammer handle. Different settings are tested from very soft springs to very rigid (four flexible settings and one rigid setting). For each setting there is a learning phase (~100 trials) and a performance phase (~20 trials) with a short break in between to retrieve experiment data. The goal given to the test subject is to try to find the best timing for using the flexible tool in the most efficient way, i.e. for hitting the target as hard as possible with the same effort.