Reinforcing Behavioural Variability: An Examination of it's Generalisability and an Analysis of U-Value as a Measure of Variability

Two experiments with college students were carried out to examine whether learned variability on two dimensions of a behaviour would generalise to a third dimension that occurred simultaneously using Ross and Neuringer's (2002) rectangle drawing task. The dimensions being measured were the sizes, shapes and the locations on the screen of the rectangles. Performances of a group receiving reinforcement independent of the variability of all three dimensions and another group receiving reinforcement contingent on the variability of two of the three dimensions were compared. Results showed that overall, the variability in the shapes and locations of the rectangles was higher when these two dimensions occurred with other two dimensions that were required to vary; however, no difference was found for the variability in sizes between the two groups. The results suggested it was likely there was generalization from reinforcing variability on sizes and locations to shape and from reinforcing variability on sizes and shapes to locations. U-value as a measure of variability was also examined, with simulated data and data collected from one of the experiments. Limitations of the measure were identified. The attentions needed to report U-values would be discussed. Cautions needed when interpreting U-values as a measure of variability would be highlighted.