Figure 15.

Human psychophysical length-discrimination measurements of visual masking effects from 11 human subjects using non-overlapping masks of varied duration (100, 300, or 500 ms). SOA here represents the period of time between the onset of the mask and the onset of the target (and so it has the opposite meaning than in Figures 3, 4 and 14). Masks (two 6° tall bars with a width of 0.5° flanking each side of each target) appeared at time 0, and targets could appear earlier (backward masking), simultaneously, or later (forward masking), in 50 ms steps. Targets were black and presented for 10 ms duration and masks were flanking black bars that abutted the target. Notice that target visibility is most greatly affected when the masks turn on and off. Reprinted from Macknik, et al. (2000).