Practical of Electroencephalography (EEG)

Question 1

Name one of the methods of EEG (alongside the advantages and disadvantages of the method)

Answer 1

Method: The Event-Related Potential Method
Advantages:
- Signals come out swiftly
- The ability to time-lock the occurrence of the event and the signals measured (synchronising the signals from the brain and the process of the tasks).
Disadvantage:
- The inverse inference issue: Researchers who want to understand the activities of the brain have to first understand the activities of the brain.

Question 2

Assumptions that should be made in terms of the examined tasks:

Answer 2

1. The actions have to be defined in time.
2. The evocation of the brain region by the task have to be consistent.
3. The time that the brain is activated by the task has to be consistent.
4. The noise and the task has to be uncorrelated (if the noise is correlated with the task, then that is not noise. Noise should be truly randomised).
5. The mean of the noise should eventually be evened out and should be 0.

Question 3

How to interpret the data from the ERPs?

Answer 3

• By average Amplitude data
• After filters and artefacts are removed, data should be averaged out across all attempts.
• With time-locking, all data should be aligned and averaged out.

Question 4

Elements that we can look at when examining ERP graphs

Answer 4

• Peak
• Peak to peak (i.e., the gap between the lowest point and the highest point of the graph)
• Area beneath the curve
• Latency

Question 5

Explain ERN (also the task that is commonly used) and the hypothesis

Answer 5

• Error Related Negativity is the 10mV negative turn of potentials when a person provides an erroneous response in an identification tasks.
• Mostly use the Flanker-Task
• Hypothesis that the ERN is more sharp and acute if the participants are told be focus on accuracy than speed (results support the hypothesis).

Question 6

Further interpretations of ERN

Answer 6

After grouping the ERN according to the its degree into four quartiles, it can be observed that;
1. participants with higher ERN tend to press the button lighter (as if they are trying to retract the wrong response)
2. participants with higher ERN tend to have a higher correct rate for the next answer (the brain is further avoiding mistakes)
3. participants with higher ERN tend to have a slower RT for the next question (the brain avoids making more mistakes)

Question 7

How do researchers cite the ERP signals

Answer 7

P5 (p = polarity; 5 = order)