Lecture 18 EEG - ERP Flashcards
(22 cards)
What does ERP stand for in EEG research?
Event-Related Potential
What is the purpose of averaging amplitude data in ERP analysis?
To reduce noise and extract the true neural response to specific events
What are the 5 assumptions for valid ERP analysis?
1) The event of interest is defined in time
2) The event consistently evokes the signal
3) The timing of the signal is consistent
4) The signal and the noise are uncorrelated
5) The noise is random with a mean=0
Why is averaging necessary in ERP research?
Because single-trial EEG data is too noisy to interpret reliably
What happens to noise when ERP segments are averaged across trials?
It cancels out, revealing a clearer signal
What defines an ERP waveform?
Its polarity (P or N) and order (e.g., P1, N1, P300)
What does P300 refer to in ERP research?
A positive peak occurring around 300 ms after a stimulus
What is one common issue in interpreting ERP components?
Reverse inference—assuming a process based on ERP shape without enough evidence
What are common methods to measure ERP amplitude?
- Peak amplitude,
- Peak-to-peak,
- Area under the curve,
- Latency
What are the two common ways to estimate ERP peak amplitude?
- Maximum peak
- Mean amplitude
What does ERP latency refer to?
The onset time of the ERP component
What are the units of ERP amplitude?
Microvolts (μV)
What is the ERN?
Error-Related Negativity, a negative ERP deflection after an error
When does the ERN typically occur?
~80–100 ms after an erroneous response
Where is the ERN observed in the EEG?
At central electrodes
What does a strong ERN response suggest about participant motivation?
That the brain is focused on detecting errors, especially under accuracy emphasis
What did Gehring et al. (1993) study with ERPs?
Whether there’s a cognitive mechanism for error detection and compensation
How did researchers relate ERN size to behavior?
By dividing ERNs into quartiles and examining response force
What behavior was observed with larger ERNs?
Participants pressed the button with less force
What does the reduced force in large ERN trials suggest?
Real-time adaptation or attempted correction after error
What is one limitation of ERP interpretation?
ERP components can reflect multiple overlapping processes
How are ERPs increasingly being used in modern research?
To predict cognitive processes using distributed patterns across all channels
