ways of studying the brain: EEG,ERP Flashcards
what is an EEG?
An electroencephalogram (EEG) works on the premise that information is processed in the brain as electrical activity in the form of action potentials or nerve impulses, transmitted along neurons. EEG scanners measure this electrical activity through electrodes attached to the scalp. Small electrical charges that are detected by the electrodes are graphed over a period of time, indicating the level of activity in the brain.
what are the 2 properties of the EEG waves that a psychologist measures?
Amplitude (the intensity or size of the activity)
frequency (the speed or quantity of an activity).
what are the 2 states an EEG pattern produces?
synchronised pattern
desynchronised pattern
what is a synchronised pattern?
A synchronised pattern is where a recognised wave form can be detected and these are usually found when we are asleep
what is a desynchronised pattern?
a desynchronised pattern is where no pattern can be detected and this usually occurs when we are awake.
what are some examples of illnesses that EEGs can detect?
epilepsy, sleep disorders, Alzheimer’s disease.
what are ERPs?
Event-Related Potentials (ERP) use similar equipment to EEG, i.e. electrodes attached to the scalp. However, the key difference is that a stimulus is presented to a participant (for example a picture/sound) and the researcher looks for activity related to that stimulus.
what is averaging in an ERP?
As ERPs are difficult to separate from all of the background EEG data, the stimulus is present many times and a statistical average response is graphed. This is called averaging and it reduces any extraneous neural activity which makes specific response to the stimulus stand out.
what are sensory ERPs?
are when wave responses occur within 100 milliseconds following the presentation of a stimulus as they represent a sensory response to the stimulus.
what are cognitive ERPs?
are when wave responses occur after 100 milliseconds after the presentation of a stimulus as they demonstrate some information processing.
AO3: how is ‘non-invasive’ a strength to EEGs and ERPs as ways of studying the brain?
one strength to EEGs and ERPs as ways of investigating the brain is that they are non-invasive techniques. This is because compared to other scanning techniques such as PET scans, EEGs and ERPs do not use radiation or involve inserting instruments directly into the brain so they are virtually risk free. These technique’s are also much cheaper to carry out and are much more readily available to use compared to other scanning techniques such as fMRIs. This means that as EEGs and ERPs are risk free and easy to do, it allows more patients to undergo these techniques meaning psychologists can gather more data on the functions of the human brain. Therefore, EEGs and ERPs allow us to develop our understanding of the human brain leading to the development of our knowledge of certain psychological phenomena such as sleeping or Alzheimer’s.
AO3: how is ‘poor spatial resolution’ a limitation to EEGs and ERPs as ways of studiying the brain?
one limitation to EEGs and ERPs as a way of investigating the brain is that they have poor spatial resolution. Spatial resolution refers to the smallest feature that a scanner can detect. This means that EEGs and ERPs only detect activity in the superficial regions of the brain meaning researchers are unable to gain information about the activity in the deeper regions of the brain due to the inability to discriminate between brain regions with higher accuracy. Therefore, this technique has limited use compared to other scanning techniques such as fMRIs which have a spatial resolution of 1-2 mm.
AO3: how is ‘good temporal resolution’ a strength to EEGs and ERPs as ways of studying the brain?
one strength to EEGs and ERPs as a way of investigating the brain is that they have good temporal resolution. This is because it takes readings every millisecond meaning it can record the brains activity in real time compared to looking at a passive brain. Therefore, these scanning techniques lead to an accurate measurement of electrical activity when undertaking a specific task compared to other scanning techniques such as fMRIs. However, EEG and ERP electrodes may be uncomfortable on the scalp for some participants meaning this discomfort could result in unrepresentative readings as the patients discomfort may be affecting their cognitive response to situations.
AO3: how is ‘electrical activity is vague’ a limitation to EEGs as a way of investigating the brain?
one limitation to EEGs as a way of investigating the brain is that electrical activity is often detected in several regions of the brain simultaneously. This means that it is harder to pinpoint the exact area or region of the brain in which the activity is higher in. Therefore, this makes it difficult for the researchers to draw accurate conclusions about the electrical brain activity found as they cant locate where this activity is within the brain. However, ERPs may be more useful to pair with EEGs as they eliminate any extraneous neural activity and are able to determine how processing is affected by a specific experimental manipulation.
