Experimental paradigm for the Auditory Conditioning (Session 1). (a) Distractor task. To distract the subjects' attention away from the auditory stimuli, a visual Stroop task with alternating attention shift conditions was presented simultaneously but not phase-locked to auditory stimulation. The visual distractor stimulus (DS) is delivered with an ISI of 1300 ms. (b) The conditioned stimulus (CS) was one of the set of five possible piano tones (range indicated at bottom of figure) and was delivered at an ISI of 4000 ± 1500 ms (randomized). The musical notation is depicted in treble clef one octave lower than the actual stimuli, for display reasons. (c) The unconditioned stimulus (US) was delivered at the subject's eye whenever the particular tone (= target; = CS+ in (b)) sounded, but not for the remaining non-target tones. At the bottom of the figure, the note f is marked red as an example. NB: As indicated by different background colors, timeline (a) runs at the same time but independently from (b) and (c), i.e. (a) is not phaselocked to (b) and (c), while the latter two are phaselocked to one another at a preselected CS-US delay. Session 0 differs from the depicted paradigm in that no US is delivered (i.e. row (c) never happens); Session 2 differs in that a keypress is substituted for the auditory note onset in row (b), and row (c) is omitted (no actual US anymore).