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HowTo 03: stimulus timing design (hands-on)
•Goal: to design an effective random stimulus presentation
→end result will be stimulus timing files
→example: using an event related design, with simple regression to analyze
→
•Steps:
→0.  given: experimental parameters (stimuli, # presentations, # TRs, etc.)
→1.  create random stimulus functions (one for each stimulus type)
→2.  create ideal reference functions (for each stimulus type)
→3.  evaluate the stimulus timing design
3.
•Step 0: the (made-up) parameters from HowTo 03 are:
→ 3 stimulus types (the classic experiment: "houses, faces and donuts")
→presentation order is randomized
→TR = 1 sec, total number of TRs = 300
→number of presentations for each stimulus type = 50 (leaving 150 for fixation)
•fixation time should be 30% ~ 50% total scanning time
→3 contrasts of interest: each pair-wise comparison
→refer to directory: AFNI_data1/ht03