1. The ERP Boot Camp Isolating Components with Difference Waves and
The Boot Camp Experiment

2. Difference Waves C1 C2 C3 E1 E2 E3
© S. J. Luck. All Rights Reserved. May be used for nonprofit educational purposes if this copyright notice is included. Permission must be obtained from the copyright holder(s) for any other use. E2
If a single component varies across conditions, it can be isolated by means of a difference wave
For this to work, the conditions must be so similar that only one component varies across conditions C3 E3 C1 C2

3. LRP = Contra minus ipsi, averaged over left & right hands
Isolating the LRP
Left Hemisphere
(Ipsi)
Right Hemisphere
(Ipsi)
Adapted from Smulders, F. T. Y., & Miller, J. O. (in press). Lateralized Readiness Potential. In S. J. Luck & E. S. Kappenman (Eds.), Oxford Handbook of Event-Related Potential Components. New York: Oxford University Press.
© S. J. Luck. All Rights Reserved. May be used for nonprofit educational purposes if this copyright notice is included. Permission must be obtained from the copyright holder(s) for any other use.
Right Hemisphere
(Contra)
Left Hemisphere
(Contra)
LRP = Contra minus ipsi, averaged over left & right hands
Smulders & Miller (2010)

4. LRP = Contra minus ipsi, averaged over left & right hands
Isolating the LRP
Adapted from Smulders, F. T. Y., & Miller, J. O. (in press). Lateralized Readiness Potential. In S. J. Luck & E. S. Kappenman (Eds.), Oxford Handbook of Event-Related Potential Components. New York: Oxford University Press.
© S. J. Luck. All Rights Reserved. May be used for nonprofit educational purposes if this copyright notice is included. Permission must be obtained from the copyright holder(s) for any other use.
LRP = Contra minus ipsi, averaged over left & right hands
Smulders & Miller (2010)

5. Nonlateralized components eliminated by subtraction
Isolating the LRP
Left Hemisphere
(Ipsi)
Right Hemisphere
(Ipsi)
Adapted from Smulders, F. T. Y., & Miller, J. O. (in press). Lateralized Readiness Potential. In S. J. Luck & E. S. Kappenman (Eds.), Oxford Handbook of Event-Related Potential Components. New York: Oxford University Press.
© S. J. Luck. All Rights Reserved. May be used for nonprofit educational purposes if this copyright notice is included. Permission must be obtained from the copyright holder(s) for any other use.
Right Hemisphere
(Contra)
Left Hemisphere
(Contra)
Nonlateralized components eliminated by subtraction
Smulders & Miller (2010)

6. Isolating the LRP
Left Hemisphere
(Ipsi)
Right Hemisphere
(Ipsi)
Adapted from Smulders, F. T. Y., & Miller, J. O. (in press). Lateralized Readiness Potential. In S. J. Luck & E. S. Kappenman (Eds.), Oxford Handbook of Event-Related Potential Components. New York: Oxford University Press.
© S. J. Luck. All Rights Reserved. May be used for nonprofit educational purposes if this copyright notice is included. Permission must be obtained from the copyright holder(s) for any other use.
Right Hemisphere
(Contra)
Left Hemisphere
(Contra)
Overall hemisphere differences eliminated by subtraction
(RHem more positive than LHem for both hands)

7. Isolating the LRP Overall hand differences eliminated by subtraction
Left Hemisphere
(Ipsi)
Right Hemisphere
(Ipsi)
Adapted from Smulders, F. T. Y., & Miller, J. O. (in press). Lateralized Readiness Potential. In S. J. Luck & E. S. Kappenman (Eds.), Oxford Handbook of Event-Related Potential Components. New York: Oxford University Press.
© S. J. Luck. All Rights Reserved. May be used for nonprofit educational purposes if this copyright notice is included. Permission must be obtained from the copyright holder(s) for any other use.
Right Hemisphere
(Contra)
Left Hemisphere
(Contra)
Overall hand differences eliminated by subtraction
(RHand more positive than LHand for both hemispheres)
Smulders & Miller (2010)

8. Isolating the LRP
Adapted from Smulders, F. T. Y., & Miller, J. O. (in press). Lateralized Readiness Potential. In S. J. Luck & E. S. Kappenman (Eds.), Oxford Handbook of Event-Related Potential Components. New York: Oxford University Press.
© S. J. Luck. All Rights Reserved. May be used for nonprofit educational purposes if this copyright notice is included. Permission must be obtained from the copyright holder(s) for any other use.
LRP provides a pure measure of the relative activation of correct vs incorrect response at each moment in time
Smulders & Miller (2010)

9. The N2pc Component
© S. J. Luck. All Rights Reserved. May be used for nonprofit educational purposes if this copyright notice is included. Permission must be obtained from the copyright holder(s) for any other use.

10. N2pc Difference Waves
© S. J. Luck. All Rights Reserved. May be used for nonprofit educational purposes if this copyright notice is included. Permission must be obtained from the copyright holder(s) for any other use.

11. Mangun, Hillyard, & Luck (1993)
The C1 Wave
Figure 10.2 in Mangun, G. R., Hillyard, S. A., & Luck, S. J. (1993). Electrocortical substrates of visual selective attention. In D. Meyer & S. Kornblum (Eds.), Attention and Performance XIV (pp ). Cambridge, Massachusetts: MIT Press. © MIT Press. This material may be used for nonprofit research and education purposes only, and it may not be reprinted or distributed in any form including print and electronic forms.
© S. J. Luck. All Rights Reserved. May be used for nonprofit educational purposes if this copyright notice is included. Permission must be obtained from the copyright holder(s) for any other use.
C1 can be isolated with Upper minus Lower difference wave
Mangun, Hillyard, & Luck (1993)

12. Isolating the P3 Wave
P3 amplitude depends on the probability of a task-defined stimulus category, not the probability of a physical stimulus
P3 probability effect cannot begin until after categorization occurs
Rare-minus-frequent difference wave isolates processes that occur after perception and categorization
P3 latency indexes “stimulus evaluation time”
© S. J. Luck. All Rights Reserved. May be used for nonprofit educational purposes if this copyright notice is included. Permission must be obtained from the copyright holder(s) for any other use.

13. P3 Difference Waves
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14. Shortcomings of Difference Waves
May not isolate a single component
Example: Rare-Frequent yields P2, N2, P3
If Cond1–Cond2 difference wave is reduced, cannot distinguish between smaller Cond1 and larger Cond2
For most components, need to look at original waveforms as well as difference waves (not for N2pc/LRP)
Ask Emily how we solved this problem for LRP
Changes in latency between Cond1 and Cond2 produce an apparent difference in amplitude
Not a problem if you view difference wave as simply meaning a difference in the time course of amplitude
© S. J. Luck. All Rights Reserved. May be used for nonprofit educational purposes if this copyright notice is included. Permission must be obtained from the copyright holder(s) for any other use.

15. The MONSTER Paradigm
Goal- Efficiently measure the speed and integrity of a broad set of specific neurocognitive processes
First step in determining the nature of deficits in a given patient group
Possibly useful for diagnosis of disease subtypes (e.g., in multiple sclerosis)
Use orthogonal subtractions to isolate specific ERP components that reflect well-characterized neurocognitive processes
Same data divided different ways to isolate different components
© S. J. Luck. All Rights Reserved. May be used for nonprofit educational purposes if this copyright notice is included. Permission must be obtained from the copyright holder(s) for any other use.

16. Stimuli and Task Task: Attend to black or white
© S. J. Luck. All Rights Reserved. May be used for nonprofit educational purposes if this copyright notice is included. Permission must be obtained from the copyright holder(s) for any other use.
Task: Attend to black or white
Press left for A (p = .80 or p = .20)
Press right for B (p = .20 or p = .80)
Left/Right and .80/.20 are counterbalanced
Stim: Duration = 200 ms
SOA = 1500 ± 150 ms
2 blocks of 512 stimuli

17. Stimuli and Task C1: Upper Checks minus Lower Checks
N2pc: Contra target minus Ipsi target
P3: Rare minus Frequent
LRP: Contra to response hand minus Ipsi to response hand
These subtractions are orthogonal -- same 1024 trials divided into different pairs of subsets and then subtracted
© S. J. Luck. All Rights Reserved. May be used for nonprofit educational purposes if this copyright notice is included. Permission must be obtained from the copyright holder(s) for any other use.

18. Recording with Biosemi ActiveTwo
Active Electrodes-
Each electrode has a small, built-in preamplifier connected to an Ag/AgCl tip
Doesn’t actually amplify; creates an ultra low impedance signal that is noise resistant
Down side: Expensive to buy and replace
Fill electrode holders with gel and plug in electrodes
Flat electrodes for mastoids, eyes, etc.
Photos from
© S. J. Luck. All Rights Reserved. May be used for nonprofit educational purposes if this copyright notice is included. Permission must be obtained from the copyright holder(s) for any other use.

19. Recording with Biosemi ActiveTwo
Single-Ended (not differential) recording
Record electrical potential between “active” and CMS (“common mode sense” -- analogous to ground)
Reference digitally, off line
DRL (“driven right leg”) electrode
Think of it as a power source for the other electrodes
High impedance
Digitization
Separate A/D converter for each electrode
Output is fiber optic cable, which connects to a box near the computer (safe, not an antenna for line noise)
Sampling rate = 1024 Hz (must be power of 2)
Built-in hardware low-pass anti-aliasing filter
No high-pass filter (DC recording)
© S. J. Luck. All Rights Reserved. May be used for nonprofit educational purposes if this copyright notice is included. Permission must be obtained from the copyright holder(s) for any other use.

20. Electrode Sites LRP P3 N2pc C1
© S. J. Luck. All Rights Reserved. May be used for nonprofit educational purposes if this copyright notice is included. Permission must be obtained from the copyright holder(s) for any other use. C1