Valid clocks: the control group performed significantly better (M= 10, S.D= 0) than the patient group (M= 5.8, S.D= 2.68) on the classification of the valid clocks t(4) = 3.5, p=.02, d = 2.22. As can be seen, Cohen's measure of effect size shows a very large effect. Importantly, the control group showed no variation on this task (all subjects correctly classified the valid clocks). By contrast, there was a noticeable tendency among the patient group to regard the valid clocks as invalid. Table 5 provides examples of responses to valid clocks by the patient group.