Schematic illustration of stimuli for experiment I. Test lead-lag click pairs (bold ticks) were preceded by silence (Baseline), 12 identical lead-lag click pairs (Buildup), 12 binaurally opposite lead-lag click pairs (Breakdown), or 11 identical lead-lag click pairs and one intervening opposite pair (Retest). Stimuli in the left column were for ITD conditions; stimuli in the right column were for ILD conditions. A, lead-lag delay (varied trial-to-trial, see text); B, 308 μs ITD; C, 10 dB ILD; D, 250 ms inter-stimulus interval between conditioner lead-lag pairs; E, 500 ms pause between conditioner and test.