Determining the location of effects and their validity for obstacle avoidance tasks
Summary
Reach-to-grasp movements, in combination with obstacle avoidance, have been the subject of many studies. However, as no widely acknowledged standards have yet been developed concerning the conduction of experiments and analysis of results, researchers in this field often have to make their own choices when studying these movements. As an example of this, data is often analyzed with the assumption of homogeneous variances between conditions. Therefore, it was the scope of this study to determine the validity of that assumption, by determining the intervals during which an effect was found while performing an obstacle avoidance task and testing these intervals for heterogeneous variances. This was done for the kinematic parameters lateral deviation, aperture and velocity. In the case of lateral deviation, heterogeneous variances were found within the interval of a significant effect. As for aperture and velocity, no effects between conditions were found. Namely for velocity, though, significant differences were still found, implying both an interference caused by some conditions, as well as the need to test for homogeneous variance if effects in other experimental setting are to be found. In conclusion, the assumption of a homogeneous variance between condition can not be made arbitrarily.