Term 4 of PSY2014S
Research methods
Methods of studying the brain
1. Behavioural
- Measuring directly observable behaviour
2. Correlational
- Reveal a pattern of brain activity that accompanies cognitive functioning
3. Causal
- Establishing cause-effect relationships. Strongest evidence.
Each method has limitations and can lead to different interpretations. It is thus important to use different
methods to see a comprehensive picture and get robust and conclusive findings.
Converging evidence: different methodologies leading to the same conclusions. Strengths compensate for
weaknesses.
Studying how brain regions are associated with different functions (localisation):
• Single dissociation
• Damage to brain Area 1 results in Function A being disrupted but Function B is intact
• Double dissociation
• Golden standard – strongest evidence (Broca and Wernicke’s area)
• Find that damage to Area 2 leaves Function A intact but Function B is disrupted
• Existence of two distinct processes
• Association
• Damage to brain Area 3 results in disruptions of Function C & D
• Common representations/processes affected
Behavioural methods to studying the brain
• Inferring brain function from observable responses
• Limitations of behavioural experiments designed to measure:
1. Accuracy
o Ceiling/Floor effects (everyone gets everything correct or incorrect – is the outcome because of a
faulty measure or the actual thing you are studying) and
o Speed-accuracy trade-off
2. Response time
o Task difficulty (the harder a task is, the longer you think before responding – if too hard can cause
slower responses than realistic)
3. Judgements
o Dishonest or don’t know how to use scale
, 4. Protocols
Strengths: test specific theories based on predictions
Weaknesses: experimental expectancy effects, task demands and no localisation or understanding of
mechanism (go through last years notes on)
Correlational Neural methods to studying the brain
• Correlate location of brain activity with changes in function/behaviour
• Correlation does not imply causation!!!
• Helps to localise mental activity
• Data can be used to establish dissociations / associations
General limitations:
1. Doesn’t show specific brain areas
2. Brain areas may be activated because they are connected
3. Brain regions may be very close and therefore not differentiated
4 primary principles on which correlational neural methods are assessed
1. Spatial resolution
Precision in localising brain area that produces a signal/activity
2. Temporal resolution
Precision in tracking changes in brain activity over time
3. Invasiveness
Degree of introducing foreign substances into the brain
4. Cost (Equipment)
• Some use electromagnetic recording methods
• Measuring summed electrical activity of neurons
• Accurate measure of activity
• Best temporal resolution (no lag btwn what happens in brain and what is shown)
Correlational Neural Methods: The EEG
• Electroencephalography (EEG)
• Metal electrodes placed on the scalp
• Records summed electrical activity of the brain surface (specifically the cortex)
• Monitors changes over time
Research methods
Methods of studying the brain
1. Behavioural
- Measuring directly observable behaviour
2. Correlational
- Reveal a pattern of brain activity that accompanies cognitive functioning
3. Causal
- Establishing cause-effect relationships. Strongest evidence.
Each method has limitations and can lead to different interpretations. It is thus important to use different
methods to see a comprehensive picture and get robust and conclusive findings.
Converging evidence: different methodologies leading to the same conclusions. Strengths compensate for
weaknesses.
Studying how brain regions are associated with different functions (localisation):
• Single dissociation
• Damage to brain Area 1 results in Function A being disrupted but Function B is intact
• Double dissociation
• Golden standard – strongest evidence (Broca and Wernicke’s area)
• Find that damage to Area 2 leaves Function A intact but Function B is disrupted
• Existence of two distinct processes
• Association
• Damage to brain Area 3 results in disruptions of Function C & D
• Common representations/processes affected
Behavioural methods to studying the brain
• Inferring brain function from observable responses
• Limitations of behavioural experiments designed to measure:
1. Accuracy
o Ceiling/Floor effects (everyone gets everything correct or incorrect – is the outcome because of a
faulty measure or the actual thing you are studying) and
o Speed-accuracy trade-off
2. Response time
o Task difficulty (the harder a task is, the longer you think before responding – if too hard can cause
slower responses than realistic)
3. Judgements
o Dishonest or don’t know how to use scale
, 4. Protocols
Strengths: test specific theories based on predictions
Weaknesses: experimental expectancy effects, task demands and no localisation or understanding of
mechanism (go through last years notes on)
Correlational Neural methods to studying the brain
• Correlate location of brain activity with changes in function/behaviour
• Correlation does not imply causation!!!
• Helps to localise mental activity
• Data can be used to establish dissociations / associations
General limitations:
1. Doesn’t show specific brain areas
2. Brain areas may be activated because they are connected
3. Brain regions may be very close and therefore not differentiated
4 primary principles on which correlational neural methods are assessed
1. Spatial resolution
Precision in localising brain area that produces a signal/activity
2. Temporal resolution
Precision in tracking changes in brain activity over time
3. Invasiveness
Degree of introducing foreign substances into the brain
4. Cost (Equipment)
• Some use electromagnetic recording methods
• Measuring summed electrical activity of neurons
• Accurate measure of activity
• Best temporal resolution (no lag btwn what happens in brain and what is shown)
Correlational Neural Methods: The EEG
• Electroencephalography (EEG)
• Metal electrodes placed on the scalp
• Records summed electrical activity of the brain surface (specifically the cortex)
• Monitors changes over time
