[Handedness in relation to reaching for an object--an analysis].

1. By using a decision tree an analysis is made about which types of handedness are possible in visually guided reaching. 2. The terms "ipsilateral handedness" and "contralateral handedness" are created. Considering the possible combinations 9 types of handedness can be described. 3. By analysis of information processing for using the right or the left hand in visually guided reaching the following facts can be described: a) The shortest time needed for decisions is found in the case of pure right- or left-handedness. b) If the object is in the symmetric plane and if the animal is not purely right- or left-handed a decision may be impossible. 4. In conclusion children should be urged decisively to use the right or left hand. However, urging should not be too early, as there is a spontaneous changing of the handedness up to the age of eight.