In a repetitive tapping task, the within-hand variability of intertap intervals is reduced when participants tap with both hands, as opposed to single-handed tapping. This bimanual advantage can be attributed to timer variance (according to the Wing-Kristofferson model). Separate timers have been proposed for each hand whose outputs are then averaged (Helmuth & Ivry, 1996, Journal of Experimental Psychology: Human Perception and Performance, 22, 278–293). Alternatively, timing might be based on sensory reafference and the bimanual advantage due to the enhancement of sensory reafferences. This alternative hypothesis was tested in three experiments. In the first experiment, we replicated the bimanual advantage in tapping with two fingers of the same hand compared with single finger tapping. Drewing, K., Hennings, M., & Aschersleben, G. (2002). The contribution of tactile reafference to temporal regularity during bimanual finger tapping. Psychological Research, 66(1), 60-70.
