Figure 2 Real and apparent locus of clicks about a boundary [Melodic line in Condition 2].

An absence of a boundary effect, or a simple constant error of temporal localisation, would give rise to mean values of 8 units, the actual separation of pre-and post-boundary click positions, as their apparent separation. A boundary effect is therefore given by the difference between the real and apparent separation of click positions on either side of a boundary. The mean values of computed apparent separations of click positions per experimental condition, summed over subjects and tunes, are shown in Table 2.