Fig. 2.

Simulated functional MRI responses and potential cue-task overlap. (A) To simulate transient cue responses, the cue was assumed to be presented for 1 s (as in the experiment), followed by a 4.5-s delay period (which varied between 2 and 6 s in the experiment), and a 0.2-s task phase (indicated by the timeline). The overlap between cue and task responses is small. (B) To simulate sustained cue responses, the cue was assumed to the presented for 5.5 s and followed immediately by a 0.2-s task phase (indicated by the timeline). The overlap between cue and task responses is quite substantial. Simulated responses were generated by employing a canonical gamma variate hemodynamic response function (Cohen, 1997).