Abstract

This paper reports an investigation about the effect of Variability factor in a perceptual task, like throwing a balls. Theoretical model used was “field model” proposed by Roca (1999). The motor task consisted in throwing the balls into a basket with a bounce on the floor, and the variability was manipulated by altering the range of basketball pressures over a standard pressure. All subjects were assigned randomly to one of four experimental groups. Each group had a different variation rank of ball pressures – 0 %, +/–20 %, +/–40 % and +/–60% –. Two experimental condition were created. In the first experimental condition the subjects didn’t have the opportunity of knowing the basketball pressure before the throwing. In the second condition, the motor task was the same, but in this experimental condition all subjects dutied bounce the balls on the floor before throwing. The results show decrease performance when variability degree increases in the first condition, but similar performane between the groups was observed in the second one.  These results can explain the variations in precision that are observed in certain sport circumstances owing to erratic or variable conditions of physics elements (material, meteorology, etc. ) and how this variability is determined.