Electroencephalography: Records? record potential differences (micro-volts)
Electroencephalography: Instruments? array of surface electrodes on the scalp
Electroencephalography: Usually used for? - Much psychological research is based on
measuring the speed and accuracy of participants' responses - (i.e. reaction time tests).
Electroencephalography: What does it record? EEG can show what happens in the brain
before, during and after a response button is pressed. (reporting continously, leading up to,
during, after) (brain response then behavioural response, see what brain does after response)
How does an Electroencephalography work? - The brain is always active, whether awake
or sleeping... or even while under anesthesia...
, Electroencephalography Questions With
Solutions
- brain cells communicate by passing electrical impulses back and forth. The purpose of EEG is
to measure the electrical activity resulting from the interactions between neurons
Electrodes:
Measures?
Instrument? -key to measuring these electrical charges
-flat, metal discs which are attached to the scalp and an EEG caps have multiple electrodes
So how many electrodes should your EEG cap have?
also available with 32, 64, 128 electrodes for?
Systems available with 4, 10 or 24 channels (3)? -EEG caps with 10-20 electrodes should
be adequate for most academic needs but depends on the research your doing
- also available with 32, 64, 128 electrodes for more advanced imaging studies
- Systems available with 4, 10 or 24 channels. These include an additional ECG (heart activity),
EMG (muscle activity) or EOG (eye movement) channel.
What about electrode placement (2)? 1) The cap must allow electrodes to be positioned
precisely... placed according to international standards.
, Electroencephalography Questions With
Solutions
2) Make sure to choose an EEG cap that is sized accurately. EEG headsets should come with a
variety of sizing options and be easily adjusted.
What about the amplifier? Signal quality is of vital importance when it comes to EEG.
The initial EEG signal is comprised of low frequency fluctuations which need to be amplified.
As a result, the amplifier is often the most expensive and defining feature of an EEG headset. If
there is one thing to check, make sure it's that the amplifier is of the highest quality.
Should I use wet or dry electrodes? - "Wet electrodes" use a conductive gel to improve
signal quality while "Dry Electrodes" do not require such gel.
- The gel used can be sticky and unpleasant for participants. For this reason many of those
wishing to use EEG for market research purposes opt for dry electrodes in order to improve
participation and compliance. This is understandable; the last thing you want is the participant
having a negative experience
Which electrodes provide better signal quality? Why? - Although many modern dry
electrodes provide excellent signal quality, wet electrodes provide better contact between
electrode and scalp, improving data quality
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