The arrangement of stimuli used in Experiment 2. The arrangement is simplified graphically by illustrating all stimuli as squarely-ramped. In the two-interval forced-choice task, one interval (randomly chosen on each trial) contains a 2-kHz 200-ms forward-masker which precedes a much briefer 2-kHz tone. As the forward-masker’s intensity is increased (dashed lines), the post-masker tone’s intensity for its threshold detection must increase (likewise dashed lines). In the other interval, no tone appears post-masker.