Abstract
In order to assess the developmental validity of the Index of Amplitude of Behavior (IAB) as a measuring instrument of social ability in preschool children, the variation of this index was studied during an academic year in an Andalusian school. The social behavior of 31 preschool children (aged five) was observed during free play period and a measure of IAB for each subject was calculated chronologically through the whole study period. According to the data obtained in this study, 300 seconds of observation is a sufficient period of time to reliably estimate the Index of Amplitude of Behavior of a subject. An adjustment of the values of the IAB of each individual towards the mean of the IAB of all the individuals of the group was detected. This suggests that the Index of Amplitude of Behavior could be considered not only as a measuring instrument of social ability, but also an useful tool to explore the effects of peer-groups in socialization.
