# fMRI Task Descriptions ## X DETECTION TASK (go/no-go) * 1 run; event-related; 216 TR; 6min 26sec * Presentation Display: * Dark Gray background [50 50 50] * White text centered on screen * Courier New, Size 40 * In-scanner Task Instructions: * *Press [goRESP] with your [respFING] finger every time you see the letter "X". You do not need to respond to other letters.* * Stimuli: Letters * X for “go” * All other letters for “no-go” trials * 258 total trials * 2/3 of run (block A, Inhibition): 120 go; 40 no-go; 12 null trials (+) * 1/3 of run (block B, Initiation): 20 go; 60 no-go; 6 null trials (+) * Order completely randomized across participants * Stimulus presentation: 400 ms * Allowed response time: 1275ms * Mean ISI: 1200 ms (jittered between 900 and 1500 ms in 100 ms increments) * 900ms, 1000ms, 1100ms, 1200ms, 1300ms, 1400ms, 1500ms as ISIs * ISI randomly selected across people * Fixation cross (+) during ISI * Total run time: 6.4 min (6 min 24 sec) * 216 total TRs * 4 sec buffer (+) at beginning of run (not including 2 auto drop TRs) * 8 sec buffer (+) at end of run * Counterbalance across participants – key response * Counterbalance A = Button 1 with index for targets (i.e., “go”), block A first * Counterbalance B = Button 2 with middle finger for targets (i.e., “go”), block A first * Counterbalance C = Button 1 with index for targets (i.e., “go”), block B first * Counterbalance D = Button 2 with middle finger for targets (i.e., “go”), block B first ## LETTER CATEGORIZATION TASK (task switching) * 1 run; event-related; 223 TR; 7min 26sec * Presentation Display: * Dark Gray background [50 50 50] * Letter centered on screen (blue or green in color) * Task cues above Letter to the right and left (blue or green in color) * Courier New, Size 44 * In-scanner Task Instructions: * *When you see the blue cue that says [upper]/[lower] press 1 with your index finger for [upper]. Press 2 with your middle finger for [lower]. When you see the green cue that says [vowel]/[consonant] press 1 with your index finger for [vowel]. Press 2 with your middle finger for [consonant].* * Stimuli: Letters * 50% upper case; 50% lowercase * 50% vowels; 50% consonants * 65 total trials * 30 switch; 30 repeat; 5 null trials * 32 trials upper/lower task; 29 trials vowel/consonant task * Stimulus presentation: 2000ms * Allowed response time: 3450ms * ISI: jittered between 1500-7500 ms * 1500, 2000, 2500, 3000, 3500, 4000, 4500, 5000, 5500, 6000, 6500, 7000, 7500 * ISI randomly selected across people * Total run time: 7.4 min (7 min 26 sec) * 223 total TRs * 4 sec buffer (+) at beginning of run (not including 2 auto drop TRs) * 8 sec buffer (+) at end of run * Counterbalance across participants – presentation side for letter judgment * Counterbalance A = Button 1 for upper/vowel; Button 2 for lower/consonant * Counterbalance B = Button 1 for lower/consonant; Button 2 for upper/vowel ## LETTER MATCH TASK (n-back) * 1 run; event-related; 266 TR; 8min 52sec * Presentation Display: * Dark Gray background [50 50 50] * White text centered on screen ( Courier New, Size 44 * In-scanner Task Instructions: * *In X MATCH Task: Press [targFING] finger for X. Press [nontargFING] finger for all other letters. In REPEAT MATCH Task: Press [targFING] finger when a letter repeats back-to-back. Press [nontargFING] finger for non-repeated letters. In 2-BACK MATCH Task: Press [targFING] finger for matches two positions back. Press [nontargFING] finger for non-matches.* * Stimuli: Letters * 3 blocks total, in randomly assigned order * ZeroBack (X as target) * OneBack (repeat as target) * TwoBack (2 back match as target) * 98 trials per block * 30 Target, 60 NonTarget, 8 Null trials * Stimulus presentation: 500ms * Allowed response time: 1375ms * Mean ISI: 1200ms (jittered between 900 and 1500 ms in 100 ms increments) * 900ms, 1000ns, 1100ms, 1200ms, 1300ms, 1400ms, 1500ms * ISI randomly selected across people * Total run time: 8.9 min (8 min 52 sec) * 266 total TRs * 2 sec buffer (+) at beginning of run (not including 2 auto drop TRs) * 4.5 second prompt at beginning of block * 8 sec buffer (+) at end of run * Counterbalance across participants – key response * Counterbalance A: Button 1 for targets, Button2 for nontargets * Counterbalance B : Button 1 for nontargets, Button2 for targets