Microteaching lesson 2

2. How to design stimulus
presentation for a
task-fMRI experiment
Ana Luísa Pinho
August 11, 2023
Department of Computer Science and Western Institute for Neuroscience
agrilopi@uwo.ca

3. Task-fMRI experiment
How to design stimulus presentation for an fMRI experiment
Participant is actively engaged in the performance of a behavioural task which can rely on:

4. Task-fMRI experiment
How to design stimulus presentation for an fMRI experiment
Participant is actively engaged in the performance of a behavioural task which can rely on:

Overt responses (ex: tapping task)

5. Task-fMRI experiment
How to design stimulus presentation for an fMRI experiment
Participant is actively engaged in the performance of a behavioural task which can rely on:

Overt responses (ex: tapping task)

Passive responses (ex: watching a movie)

6. Who has ever participated or
attended a task-fMRI experiment?
How to design stimulus presentation for an fMRI experiment

7. Overview
How to design stimulus presentation for an fMRI experiment

8. Overview

Goal
How to design stimulus presentation for an fMRI experiment

9. Overview

Goal

Induce human subject to do or experience the psychological states you’re studying
How to design stimulus presentation for an fMRI experiment

10. Overview

Goal

Induce human subject to do or experience the psychological states you’re studying

Effectively detect brain signals related to those psychological states
How to design stimulus presentation for an fMRI experiment

11. Overview

Goal

Design Method

Induce human subject to do or experience the psychological states you’re studying

Effectively detect brain signals related to those psychological states
How to design stimulus presentation for an fMRI experiment

12. Overview

Goal

Design Method

Induce human subject to do or experience the psychological states you’re studying

Effectively detect brain signals related to those psychological states

You control what to present and when
How to design stimulus presentation for an fMRI experiment

13. Overview

Goal

Design Method

Induce human subject to do or experience the psychological states you’re studying

Effectively detect brain signals related to those psychological states

You control what to present and when

Two kinds of considerations: Psychological and Statistical
How to design stimulus presentation for an fMRI experiment

14. Types of Experimental Designs
1 Block-Design
2 Event-Related Design
3 Mixed Designs
4 Naturalistic-Stimuli Design
How to design stimulus presentation for an fMRI experiment

15. Blocked & Event-Related Designs
How to design stimulus presentation for an fMRI experiment
Block Design: Similar Events are grouped
Event-Related Design: Events are mixed
Time
Time

16. Blocked & Event-Related Designs
How to design stimulus presentation for an fMRI experiment
Block Design: Similar Events are grouped
Event-Related Design: Events are mixed
Time
Time
Familiar
vs.
Non-Familiar

17. Psychological Considerations

No fixed rules, but principles

You must understand your task domain
How to design stimulus presentation for an fMRI experiment

Does the task induce the subject to think the way you want?
1 Stimulus Predictability
2 Time on Task
3 Participant Strategy
4 Temporal Precision of Psychological Manipulations
5 Unintended Psychological Activity

18. Stimulus Predictability
How to design stimulus presentation for an fMRI experiment

19. Stimulus Predictability
How to design stimulus presentation for an fMRI experiment

Principle: Predictability influences psychological state

20. Stimulus Predictability
How to design stimulus presentation for an fMRI experiment

Principle: Predictability influences psychological state

Example: Go-No-Go Task

“Press fast, but withhold if X”

21. Stimulus Predictability
How to design stimulus presentation for an fMRI experiment

Principle: Predictability influences psychological state

Example: Go-No-Go Task

“Press fast, but withhold if X”
N

22. Stimulus Predictability
How to design stimulus presentation for an fMRI experiment

Principle: Predictability influences psychological state

Example: Go-No-Go Task

“Press fast, but withhold if X”
P
N

23. Stimulus Predictability
How to design stimulus presentation for an fMRI experiment

Principle: Predictability influences psychological state

Example: Go-No-Go Task

“Press fast, but withhold if X”
P R
N

24. Stimulus Predictability
How to design stimulus presentation for an fMRI experiment

Principle: Predictability influences psychological state

Example: Go-No-Go Task

“Press fast, but withhold if X”
P R S
N

25. Stimulus Predictability
How to design stimulus presentation for an fMRI experiment

Principle: Predictability influences psychological state

Example: Go-No-Go Task

“Press fast, but withhold if X”
P R S X
N

26. Stimulus Predictability
How to design stimulus presentation for an fMRI experiment

Principle: Predictability influences psychological state

Example: Go-No-Go Task

“Press fast, but withhold if X”
P R S X X
N

27. Stimulus Predictability
How to design stimulus presentation for an fMRI experiment

Principle: Predictability influences psychological state

Example: Go-No-Go Task

“Press fast, but withhold if X”
P R S X X X
N

28. Stimulus Predictability
How to design stimulus presentation for an fMRI experiment

Principle: Predictability influences psychological state

Example: Go-No-Go Task

“Press fast, but withhold if X”
P R S X X X X
N

29. Stimulus Predictability
How to design stimulus presentation for an fMRI experiment

Principle: Predictability influences psychological state

Example: Go-No-Go Task

“Press fast, but withhold if X”
P R S X X X X
N
N

30. Stimulus Predictability
How to design stimulus presentation for an fMRI experiment

Principle: Predictability influences psychological state

Example: Go-No-Go Task

“Press fast, but withhold if X”
P R S X X X X
P
N
N

31. Stimulus Predictability
How to design stimulus presentation for an fMRI experiment

Principle: Predictability influences psychological state

Example: Go-No-Go Task

“Press fast, but withhold if X”
P R S X X X X
P X
N
N

32. Stimulus Predictability
How to design stimulus presentation for an fMRI experiment

Principle: Predictability influences psychological state

Example: Go-No-Go Task

“Press fast, but withhold if X”
P R S X X X X
P X X
N
N

33. Stimulus Predictability
How to design stimulus presentation for an fMRI experiment

Principle: Predictability influences psychological state

Example: Go-No-Go Task

“Press fast, but withhold if X”
P R S X X X X
P X X R
N
N

34. Stimulus Predictability
How to design stimulus presentation for an fMRI experiment

Principle: Predictability influences psychological state

Example: Go-No-Go Task

“Press fast, but withhold if X”
P R S X X X X
P X X R Q
N
N

35. Stimulus Predictability
How to design stimulus presentation for an fMRI experiment

Principle: Predictability influences psychological state

Example: Go-No-Go Task

“Press fast, but withhold if X”
P R S X X X X
P X X R Q T
N
N

36. Stimulus Predictability
How to design stimulus presentation for an fMRI experiment

Principle: Predictability influences psychological state

Example: Go-No-Go Task

“Press fast, but withhold if X”
P R S X X X X
P X X R Q T X
N
N

37. Stimulus Predictability
How to design stimulus presentation for an fMRI experiment

Principle: Predictability influences psychological state

Example: Go-No-Go Task

“Press fast, but withhold if X”
P R S X X X X
P X X R Q T X

The predictability of the no-go stimulus determines how hard it is to not respond
N
N

38. Stimulus Predictability
How to design stimulus presentation for an fMRI experiment

Principle: Predictability influences psychological state

Example: Go-No-Go Task

“Press fast, but withhold if X”
P R S X X X X
P X X R Q T X

The predictability of the no-go stimulus determines how hard it is to not respond
N
N
Blocks:
Psychological / Neural Preparation

39. Stimulus Predictability
How to design stimulus presentation for an fMRI experiment

Principle: Predictability influences psychological state

Example: Go-No-Go Task

“Press fast, but withhold if X”
P R S X X X X
P X X R Q T X

The predictability of the no-go stimulus determines how hard it is to not respond
N
N
Blocks:
Psychological / Neural Preparation
Events:
More equal inhibitory demand
on each “X” trial

40. Time on Task (1/2)
How to design stimulus presentation for an fMRI experiment

41. Time on Task (1/2)
How to design stimulus presentation for an fMRI experiment

Principle: You can only image what subjects are doing, so they should be doing what
you want as much of the time as possible

42. Time on Task (1/2)
How to design stimulus presentation for an fMRI experiment

Principle: You can only image what subjects are doing, so they should be doing what
you want as much of the time as possible

Example: Famous-Face Recognition

Fast, automatic process

43. Time on Task (1/2)
How to design stimulus presentation for an fMRI experiment

Principle: You can only image what subjects are doing, so they should be doing what
you want as much of the time as possible

Example: Famous-Face Recognition

Fast, automatic process
Condition A – Famous Condition B – Not Famous

44. Time on Task (1/2)
How to design stimulus presentation for an fMRI experiment

Principle: You can only image what subjects are doing, so they should be doing what
you want as much of the time as possible

Example: Famous-Face Recognition

Fast, automatic process
Time
3 seconds
...

45. Time on Task (2/2) 
3 seconds of picture viewing
How to design stimulus presentation for an fMRI experiment

46. Time on Task (2/2) 
3 seconds of picture viewing
Recognition: 250ms
How to design stimulus presentation for an fMRI experiment

47. Time on Task (2/2) 
3 seconds of picture viewing
Recognition: 250ms
“What was he in?”
How to design stimulus presentation for an fMRI experiment

48. Time on Task (2/2) 
3 seconds of picture viewing
Recognition: 250ms
“What was he in?”
“The Matrix movies!, those were so cool...”
How to design stimulus presentation for an fMRI experiment

49. Time on Task (2/2) 
3 seconds of picture viewing
Recognition: 250ms
“What was he in?”
“The Matrix movies!, those were so cool...”
How to design stimulus presentation for an fMRI experiment
I even used to wear the same type of jacket!

50. Time on Task (2/2) 
3 seconds of picture viewing
Recognition: 250ms
“What was he in?”
“The Matrix movies!, those were so cool...”
How to design stimulus presentation for an fMRI experiment
I even used to wear the same type of jacket!
“Get back on task.”

51. Time on Task (2/2) 
3 seconds of picture viewing
Recognition: 250ms
“What was he in?”
“The Matrix movies!, those were so cool...”
How to design stimulus presentation for an fMRI experiment
I even used to wear the same type of jacket!
“Get back on task.”
Time of the process we don’t care about

52. Time on Task (2/2) 
3 seconds of picture viewing
Recognition: 250ms
“What was he in?”
“The Matrix movies!, those were so cool...”
How to design stimulus presentation for an fMRI experiment
I even used to wear the same type of jacket!
“Get back on task.”
Time of the process we don’t care about
Standard Event-Related Design:
many extraneous processes

53. Time on Task (2/2) 
3 seconds of picture viewing
Recognition: 250ms
“What was he in?”
“The Matrix movies!, those were so cool...”
How to design stimulus presentation for an fMRI experiment
I even used to wear the same type of jacket!
“Get back on task.”
Time of the process we don’t care about
Standard Event-Related Design:
many extraneous processes

Fast-Event Related Design:

Prevent spontaneous processes

Collect more data from effect-of-interest

54. Participant Strategy
How to design stimulus presentation for an fMRI experiment

55. Participant Strategy
How to design stimulus presentation for an fMRI experiment

Different stim configurations afford different strategies

Example: the Stroop task

56. Participant Strategy
How to design stimulus presentation for an fMRI experiment

Different stim configurations afford different strategies

Example: the Stroop task
Name the COLOR in which the word is printed as fast as you can!

57. Participant Strategy
How to design stimulus presentation for an fMRI experiment

Different stim configurations afford different strategies

Example: the Stroop task
Name the COLOR in which the word is printed as fast as you can!
blue

58. Participant Strategy
How to design stimulus presentation for an fMRI experiment

Different stim configurations afford different strategies

Example: the Stroop task
Name the COLOR in which the word is printed as fast as you can!
blue red

59. Participant Strategy
How to design stimulus presentation for an fMRI experiment

Different stim configurations afford different strategies

Example: the Stroop task
Name the COLOR in which the word is printed as fast as you can!
blue red green

60. Participant Strategy
How to design stimulus presentation for an fMRI experiment

Different stim configurations afford different strategies

Example: the Stroop task
Name the COLOR in which the word is printed as fast as you can!
blue red green red

61. Participant Strategy
How to design stimulus presentation for an fMRI experiment

Different stim configurations afford different strategies

Example: the Stroop task
Name the COLOR in which the word is printed as fast as you can!
blue red green yellow
red

62. Participant Strategy
How to design stimulus presentation for an fMRI experiment

Different stim configurations afford different strategies

Example: the Stroop task
Name the COLOR in which the word is printed as fast as you can!
blue red green yellow
red blue

63. Participant Strategy
How to design stimulus presentation for an fMRI experiment

Different stim configurations afford different strategies

Example: the Stroop task
Name the COLOR in which the word is printed as fast as you can!
blue red green yellow
red blue yellow

64. Participant Strategy
How to design stimulus presentation for an fMRI experiment

Different stim configurations afford different strategies

Example: the Stroop task
Name the COLOR in which the word is printed as fast as you can!
blue red green yellow
red blue yellow red

65. Participant Strategy
How to design stimulus presentation for an fMRI experiment

Different stim configurations afford different strategies

Example: the Stroop task
Name the COLOR in which the word is printed as fast as you can!
blue red green yellow
OK, now do it again!
red blue yellow red

66. Participant Strategy
How to design stimulus presentation for an fMRI experiment

Different stim configurations afford different strategies

Example: the Stroop task
Name the COLOR in which the word is printed as fast as you can!
blue red green yellow
OK, now do it again!
red blue yellow red
red

67. Participant Strategy
How to design stimulus presentation for an fMRI experiment

Different stim configurations afford different strategies

Example: the Stroop task
Name the COLOR in which the word is printed as fast as you can!
blue red green yellow
OK, now do it again!
red blue yellow red
red blue

68. Participant Strategy
How to design stimulus presentation for an fMRI experiment

Different stim configurations afford different strategies

Example: the Stroop task
Name the COLOR in which the word is printed as fast as you can!
blue red green yellow
OK, now do it again!
red blue yellow red
red blue red

69. Participant Strategy
How to design stimulus presentation for an fMRI experiment

Different stim configurations afford different strategies

Example: the Stroop task
Name the COLOR in which the word is printed as fast as you can!
blue red green yellow
OK, now do it again!
red blue yellow red
red blue red blue

70. Participant Strategy
How to design stimulus presentation for an fMRI experiment

Different stim configurations afford different strategies

Example: the Stroop task
Name the COLOR in which the word is printed as fast as you can!
blue red green yellow
OK, now do it again!
red blue yellow red
red blue red blue red

71. Participant Strategy
How to design stimulus presentation for an fMRI experiment

Different stim configurations afford different strategies

Example: the Stroop task
Name the COLOR in which the word is printed as fast as you can!
blue red green yellow
OK, now do it again!
red blue yellow red
red blue red blue red green

72. Participant Strategy
How to design stimulus presentation for an fMRI experiment

Different stim configurations afford different strategies

Example: the Stroop task
Name the COLOR in which the word is printed as fast as you can!
blue red green yellow
OK, now do it again!
red blue yellow red
red blue red blue red green blue

73. Participant Strategy
How to design stimulus presentation for an fMRI experiment

Different stim configurations afford different strategies

Example: the Stroop task
Name the COLOR in which the word is printed as fast as you can!
blue red green yellow
OK, now do it again!
red blue yellow red
red blue red blue red green blue yellow

74. Participant Strategy
How to design stimulus presentation for an fMRI experiment

Different stim configurations afford different strategies

Example: the Stroop task
Name the COLOR in which the word is printed as fast as you can!
blue red green yellow
OK, now do it again!
red blue yellow red
red blue red blue red green blue yellow yellow

75. Participant Strategy
How to design stimulus presentation for an fMRI experiment

Different stim configurations afford different strategies

Example: the Stroop task
Name the COLOR in which the word is printed as fast as you can!
blue red green yellow
OK, now do it again!
Compatible: green yellow red blue
Incompatible: red blue green yellow
Cognitive control: Incompatible vs. Compatible
red blue yellow red
red blue red blue red green blue yellow yellow

76. Participant Strategy
How to design stimulus presentation for an fMRI experiment

Different stim configurations afford different strategies

Example: the Stroop task
Name the COLOR in which the word is printed as fast as you can!
blue red green yellow
OK, now do it again!
Compatible: green yellow red blue
Incompatible: red blue green yellow
Cognitive control: Incompatible vs. Compatible

If compatible stimuli are predictable, then task is different

Predictable compatible stimuli induce READING

Unpredictable compatible stimuli induce COLOR NAMING
red blue yellow red
red blue red blue red green blue yellow yellow

77. Participant Strategy
How to design stimulus presentation for an fMRI experiment

Different stim configurations afford different strategies

Example: the Stroop task
Name the COLOR in which the word is printed as fast as you can!
blue red green yellow
OK, now do it again!
Compatible: green yellow red blue
Incompatible: red blue green yellow
Cognitive control: Incompatible vs. Compatible

If compatible stimuli are predictable, then task is different

Predictable compatible stimuli induce READING

Unpredictable compatible stimuli induce COLOR NAMING
Block Design:
Confounds control
w/ reading.
You will get
activation...
but for the
wrong reason.
red blue yellow red
red blue red blue red green blue yellow yellow

78. The n-back task is a continuous performance task that is commonly
used to measure working-memory (the cognitive system that holds
information temporarily). The subject is presented with a sequence of
stimuli, and the task consists of indicating when the current stimulus
matches the one from n steps earlier in the sequence. If you were to
implement a 2-back vs. 0-back, would you use a block-design or event-
related design?
How to design stimulus presentation for an fMRI experiment
Note:

"2-Back" means that you have to remember the position of the item two turns back.

“0-Back” means that you have to remember whether the stimuli was ever presented before or not.

79. Summary & Resources
How to design stimulus presentation for an fMRI experiment

80. Summary & Resources
How to design stimulus presentation for an fMRI experiment

Defined task-fMRI experiments

81. Summary & Resources
How to design stimulus presentation for an fMRI experiment

Defined task-fMRI experiments

Enumerated different types of Experimental Designs used in Cognitive Neuroscience

82. Summary & Resources
How to design stimulus presentation for an fMRI experiment

Defined task-fMRI experiments

Enumerated different types of Experimental Designs used in Cognitive Neuroscience

Described Block-Designs and Event-Related Designs

83. Summary & Resources
How to design stimulus presentation for an fMRI experiment

Defined task-fMRI experiments

Enumerated different types of Experimental Designs used in Cognitive Neuroscience

Described Block-Designs and Event-Related Designs

Differentiated Psychological Considerations to take into account during design implementation

84. Summary & Resources
How to design stimulus presentation for an fMRI experiment

Defined task-fMRI experiments

Enumerated different types of Experimental Designs used in Cognitive Neuroscience

Described Block-Designs and Event-Related Designs

Differentiated Psychological Considerations to take into account during design implementation
Functional Magnetic Resonance Imaging
Third Edition
Scott A. Huettel, Allen W. Song, and Gregory
McCarthy
Oxford University Press
Chapter 9
https://expyriment.org/