Figure 1.

Testing protocol and behavioral paradigms. A, Overview of the testing protocol for each participant. Familiarization sessions were run on Friday afternoon in the week before testing. MRI test sessions were conducted on Monday and Friday at the same time for each participant. Three days of training sessions were run in the interim period (Tuesday, Wednesday, Thursday). B, Example display sequence for the multitasking paradigm. The task comprised three conditions: single task visual manual, in which participants made a manual response to one of two shapes (a “spikey” or a “smoothy” shape); single task auditory manual, in which participants responded manually to an auditory tone (two easily discernible, complex tones); and multitask, in which both single tasks were presented concurrently and each required a separate response. C, Visual search paradigm performed by the irrelevant training group. Participants judged the orientation of a letter “T” target (rotated by 90° clockwise or counterclockwise) presented among 7 (small set size), 11 (medium set size), or 15 (large set size) rotated letter “L” distractors. This is a classic inefficient search paradigm.