Awareness of both global uncertainty and feedback in human time estimation.

Recent behavioral studies have shown that humans possess self-awareness of their individual timing ability in that they can discern the direction of their timing error. However, in these studies which included a single repeat (re-do) trial for each duration, it remains unclear whether the reduction in errors in the re-do trials was due to self-awareness of individual timing ability or because the participants used the feedback from the initial trials to improve on the re-do ones. To investigate this further, we conducted a behavioral study in which subjects were divided into two groups: one in which the "re-do" phase occurred frequently, but not always (80% of trials; called the "high-double" group), and one in which re-do trials were rare (20% of trials; called the "low-double" group). This was done to test the possibility of subjects relying on the re-do trials as a method of improvement. Subjects significantly improved in their performance on re-do trials regardless of whether re-dos were rare or frequent. Further, an unexpected finding was observed, where subjects in the low-double group also overall performed better than those in the high-double group. This finding suggests that subjects, knowing that re-do opportunities were rare, engaged better timing at the outset; yet these subjects still improved on re-do trials, suggesting humans are able to incorporate both global uncertainty and feedback.