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Cognitive psyc > week 2 - methods to study cognition > Flashcards

week 2 - methods to study cognition Flashcards

1
Q

three different approaches

A

experimental cognitive psychology

cognitive neuropsychology

cognitive neuroscience

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2
Q

experimental cognitive psychology - what

A

studying behaviour in controlled lab conditions

shed light onto cognitive processes by using clever experimental manipulations

uses behavioural measures (instead of brain measures)
- reaction time
- accuracy
(indirect measures)

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3
Q

experimental cognitive psychology - an experiment

A

stroop test

tests whether word reading is automatic
if it interferes with colour naming

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4
Q

experimental cognitive psychology - strengths

A

successful at generating theories about cognition that can be tested in neuroscience (only when cognitive psychologists had developed reasonable accounts of healthy human cognition that the performance of brain-damaged patients could be understood fully.)

has made a huge contribution to making psychology a more empirical science (quantitative)

first systematic approach to understanding cognition

the source of most theories and tasks used by the other appoaches

flexible and can be applied to any aspect of cognition

has produced numerous replicated findings

has strongly influences social, clinical and developmental psyc

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5
Q

experimental cognitive psychology - weaknesses

A

ecological validity - can we generalise findings outside the lab (behavioural differences)

face validity - only provides indirect measures of cognitive processes, so how do we know what we are measuring is correct as the mind is very complicated

do psychological concepts even exist? - cant assume something exists because we have given it a name

difficulty in falsifying

paradigm specificity - sometimes findings do not generalise

lack of an overarching theoretical framework

most cognitive tasks are complex and involve many different processes

theories vague and hard to test empirically

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6
Q

cognitive neuropsychology - what

A

Studying cognition in patients with brain injury
(lesions)
this tells us about cognition in healthy individuals

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7
Q

cognitive neuropsychology - goal

A

to find which cognitive functions are impaired and which ones are preserved when a given brain region is damaged

tells us which area affects what

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8
Q

cognitive neuropsychology - research

A

search of dissociations
which occur when a patient has normal performance on one task (task X) but is impaired on a second one (task Y).

must avoiding sweeping conclusions!!
- differences in complexity
- opposite patterns

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9
Q

cognitive neuropsychology - single case studies vs case series

A

single case
- only access to one patient with pattern of cognitive impairment
- assume certain uniqueness to each case

in recent years move towards case series
- several patients with similar cognitive impairment are tested
- then data is compared and variation across patients is assessed
- provides richer data
- able to identify and de-emphasise outliers

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10
Q

cognitive neuropsychology - strengths

A

allows us to draw causal inferences about the relationship
between brain areas and cognitive processes and behaviour.

ability to provide evidence falsifying plausible cognitive theories.

“produces large-magnitude phenomena which can be initially theoretically highly counterintuitive”

combined fruitfully with cognitive neuroscience

Discovering the true extent of the brain areas adversely affected by a lesion facilitates the task of relating brain functioning to cognitive processing and task performance.

double dissociations have provided strong evidence for various processing modules

causal links can be shown between brain damage and cognitive performance

straddles the divide between cognitive psychology and cognitive neuroscience

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11
Q

cognitive neuropsychology - limitations

A

no baseline - we don’t know exactly what the patient could do before their injury, therefore have to make assumptions

theoretical assumptions seem too extreme

generalisation - lesions in some areas of the brain are relatively common while others are rare. same deficits in different people?

modularity - cognitive process X is likely distributed across multiple areas not just one - detailed cognitive processes and their interconnectedness are often not specified

lesions can alter the organisation of the brain
- compensatory major strategies not found in healthy individuals

brain plasticity complicated interpreting findings

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12
Q

cognitive neuroscience - what

A

relates brain structure and brain function to cognitive processes

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13
Q

cognitive neuroscience - how

A

typically done by recording brain activity while participants perform cognitive tasks

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14
Q

cognitive neuroscience - the brain

A

very complicated
highly connected

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15
Q

cognitive neuroscience - strengths

A

great variety of techniques offering excellent temporal or spatial resolution

functional specialisation and brain integration can be studied

TMS is flexible and permits causal inferences

rich data permit assessment of integrated brain processing as well as specialised functioning

resolution of complex theoretical issues

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16
Q

cognitive neuroscience - limitations

A

functional neuroimaging techniques provide essentially correlational data

does it help us understand cognition? - need to q whether the info that we are gaining actually helps us understand cognition

much over-interpretation of data involving reverse inferences

there are many false positives and replication failures

it has generated very few new theories
/ is a theory being tested? or just saying it exists

difficulty in relation brain activity to psychological processes

expensive / invasive - often mean sample sizes small (generalisable?)

17
Q

cognitive neuroscience - tools to study the brain

A

electrophysiology - single cell and EEG

structural imaging (MRI)

functional imaging (fMRI)

brain stimulation (TMS)

18
Q

cognitive neuroscience
- electrophysiology
- single cell recordings

A

○ Very small electrodes that you can implant in the brains of people and animals that record from one neuron
can record neural activity from within axon (intracellular) or from other axon membrane (extracellular)

usually, only obtained from animals? - when is this justified
- sometimes can record patients with epilepsy (during surgery)
Patients have to sit in the hospital waiting to have a seizure in order to identify the cause
- So these patients get involved in research where cognitive scientists come along and ask if they want to do cognitive tests
Rare opportunity

19
Q

cognitive neuroscience
- electrophysiology
- electroencephalography (EEG)

A

electrical activity of a large no. of neurons all firing together

recorded via electroded on the scalp

allows us to measure neural activity in esssentially real time (ms scale)

non invasive

20
Q

cognitive neuroscience
- electrophysiology
- electroencephalography (EEG)

what does it record?

A

event-related potentials (ERPs)

measure EEG response to same stimulus task over and over

average waveform to generate an ERP

we can compare the ERPs between differnet psychological conditions
eg Paying attention vs not paying attention

21
Q

cognitive neuroscience
- electrophysiology

advantages of EEG/ERP

A

very good temporal resolution (ms)

portable and relatively cheap

22
Q

cognitive neuroscience
- electrophysiology

limitations of EEG/ERP

A

poor spatial resolution (cm) (where in brain)
- infinite possible origins for any signal recorded on scalp
- The electrical activity doesnt necessarily come from underneath the electrode it was detected
- Not a lot of info of which part of brain is responsible

23
Q

cognitive neuroscience
- magnetic resonance imaging (MRI)

A

Works by putting someone in an extremely strong magnet
- An enormously powerful magnetic field
- Very dangerous –> lots of safety screening to be allowed near it

24
Q

cognitive neuroscience
- magnetic resonance imaging (MRI)

basic principle

A

The reason for the extremely powerful magnet is because basically in your brain and entire body you have protons in water molecules and these protons are spinning

When you put them in a very powerful magnet these protons start sponning and lining up with the direction of the magnetic field

In an MRI scanner the magnetic field goes through the hole in the middle and all of the protons in the water molecules in your brain start lining up with that magnetic field

The way MRI works is that it then distrupts the spin of these protons by firing short radio frequency pulses at your head (these aren’t dangerous)

This makes the proton wobble

The amount that it wobbles will change the magnetic field that is being generated by your protons in the water molecules
We can measure how long it takes for those protons to stop wobbling

Because we know protons in different types of tissues stop wobbling at different rates
- They take different amounts of time to go back to point in the direction of the magnetic field of the magnetic
○ “to relax”

If we do this in a clever way using gradients ect.

We can create images of what tissue we think exists at each point inside this persons head
- Based on how much time it takes for the protons in that part of the head to return to facing in line with the magnetic field of the scanner after we’ve turned off the radio frequency pulse

25
Q

cognitive neuroscience
- structural MRI

A

Can look at the outside and inside of brain
Extremely powerful in terms of its spatial resolution
- What we can vabout where things are in the brain

26
Q

cognitive neuroscience
- structural MRI: diffusion tensor imaging (DTI)

A

can image white matter fibres (bundles of axons) by measuring the direction of water diffusion

allows us to study how cognition/perception is supported by connections between brain regions

27
Q

cognitive neuroscience
- functional MRI

A

does not measure neurons directly

measure the blood oxygenation level-dependent signal (BOLD)
- active neurons need O2
- the brain starts supplying O2 to acyive areas producing an overshoot is oxygenated blood
- oxygenated blood causes less magnetic field disturbance than deoxygenated blood so active brain regions will have higher signal

28
Q

cognitive neuroscience
- functional MRI

advantages

A

very good spatial resolution (mm)
where

29
Q

cognitive neuroscience
- functional MRI

limitations

A

poor temporal resolution (seconds)
when

not a measure of neurons themselves
- requires an indirect inference that neurons are firing because that part of the brain is using more oxygen

30
Q

cognitive neuroscience
brain stimulation techniques

A

to know if a particular part of your brain is important for a cognitive process we need to change the activity of that part of the brain and show that it changes behaviour

we need causality (not just correlation)

31
Q

cognitive neuroscience
brain stimulation techniques

Transcranial magnetic stimulation (TMS)

A

An electromagnet which produces very powerdul and focal magnetic fields
short magenetic pules that briefly affect electrical activity in a localised patch of the brain tissue under the coil

If you put this on top of someones head you can produce a magnetic field that goes inside the skull

When it gets inside the skull depending on the type of magnetic field that you produce you can either:
- Induce electrical activity in the cells it passes through
- You can stop cells firing (give people brief brain injuries)
can have positive or negative task performance

This gives causality

Eg. Using fMRI find corrolation, then use TMS to see if you can abolish this process
○ This gives causal evidence

32
Q

cognitive neuroscience
brain stimulation

advantages

A

causal evidence that a particular brain region is important for a cognitive function

mostly non-invasive
- safe and painless for healthy populations

Cognitive psyc (23 decks)

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