W3 Neuroscience Research Design Flashcards
What are the IVs and DVs in a purely experimental design?
- IV = the variable being manipulated
- DV = the variable being measured, to see if changing levels of the IV is linked with changes in the DV
How does the IV differ in cognitive neuroscience?
the IV is also measured, and not necessarily manipulated
Example = Effect of age on brain function, eg. AGE = IV even though you are not manipulated age
How does cause and effect link to IV and DV?
- Cause (IV)
- Effect (DV)
Example: neuropsychological condition (IV) is linked with changes to cognition (DV)
However if IV is still measured, it is harder to establish casualty
What’s an example of using multiple IVs and DVs in a study?
Manipulate working memory load (IV) and measure individuals working memory capacity (IV) to determine effect on a vigilance task (DV)
The 3 DVs include reaction time, accuracy and BOLD activation
How can a psychological process either be a DV or an IV?
- it depends on the context
- Example = measuring memory (DV) or manipulating memory load (IV)
effects of caffeine (IV) on anxiety (DV)?
Or effects of anxiety (IV) on caffeine consumption? (DV)
What are the top 7 common DVs in cog. neuroscience?
- Electroencephalopathy (EEG)
- Eye tracking
- Event related potentials ERPs
- Diffusion tensor imaging (DTI)
- fMRI
- Magnetoencephalography (MEG)
- Accuracy, response time (RT)
What are the top 4 common IVs in cog. neuroscience?
- presence of a neuropsychological condition vs. healthy controls
- Presence of a type of stimulus over another, fear vs. neutral
- Performance on a task vs. another task, spatial vs. verbal
- transcranial magnetic stimulation (TMS)
What are the pros and cons of repeated measures design?
What is the solution?
Pros: increased Power as individual differences are accounted for as they are constant across all conditions
Cons: potential order effects, practice effects, fatigue
Solution: counterbalancing
What does counterbalancing achieve?
- alternating the order of conditions that participants enter into first,
- practice effects still occur, but is balanced across conditions, but it mitigates order effects, without you can have a confound of order effects
Why does the time period between RM experimental conditions need to be considered?
anything you do to participants (experimental manipulation) that may affect them for several hours,
eg. drinking coffee, inducing a negative mood, might have an effect on the next IV condition they go into
What are the pros and cons of independent groups design?
What is the solution?
Pros: no potential order effects
Cons: pre-existing individual differences on the DV from different individuals being in different conditions
Solution: random assignment to conditions, and large N sample, balances out individual differences and reduces risk of outliers, more likely that scores reflect the effect of the IV instead of individual differences
What are manipulation checks?
to check whether the IV is functioning as intended, as it can affect results if IV is not working on DV
(Not always feasible to do manipulation check, eg. age, but is useful)
What is an example of a mixed design study?
3 age groups of people and 2 working memory conditions,
- separate age groups (IG IV) but everyone is in both memory conditions (RM IV)
What is an example of a manipulation check?
EXAMPLE - Mood on memory -
IV: inducing positive, neutral or negative mood
MC = ask people to rate their mood on a likert scale of pos-neg - and check whether conditions produced significantly different mood ratings corresponding to the IV conditions, positive moods should produce high positive moods, etc.
What if the manipulation check didn’t pass, eg. people rated similar mood ratings on a mood induction IV?
If you got similar mood ratings throughout the conditions, you can’t draw conclusions about mood on memory if you haven’t effectively manipulated mood to study memory
What is error variance and what do you need to check?
- variables that are not the focus of the study, need to determine if it significantly influenced the IV:
- ASK = has this error variance systematically varied with the levels of the IV?
What are cofounding variables? + example?
- A type of variance systematically varied with the levels of the IV and could impact the DV
Example: order effects - in a within-groups design, if all participants do A and then B, and performance on a task is significantly lower in B for no other reason apart from the fact that they did B second
What makes order effects a potential confounding variable?
Order is a confounding variable because it is impossible to determine whether the decreased performance was due to order effects, the IV or a combination of both
Solution = Counterbalancing this means that the decrease in performance is no longer co-varying with levels of the IV, easier to make a statement that performance is due to the IV memory load rather than the order effect
What are non-systematic sources of error variance?
are often present and cause background noise - can’t get rid of - make sure they don’t systematically co-vary with levels of the IV
Eg. background noise in a laboratory study that could impact participants performance
How does Non-systematic sources of error variance differ between IG and RM designs?
- In an independent-measures design, if ONE IV group is affected by background noise, and the other is NOT = CONFOUND
In RM design, if something is affecting their performance in ALL of their conditions, NOT IDEAL BUT NOT A CONFOUND, because it’s not systematically impacting ONE level of the IV over the OTHERS
What is the Difference Score Approach?
1.when a DV (accuracy, RTs, ERP) is compared between two conditions, and these two conditions are the same except for one topic of interest
- mostly used in RM conditions
- If there is a difference between conditions, then it can be attributed to the one difference between conditions
What is the difference score in the Stroop effect?
RTs on the congruent - incongruent condition produces a difference score for semantic processing
Differences in trials strongly suggest its due to a difference in congruency of words and colours, and not colour processing, because everything else but the congruency of the words/colours is kept constant
What is an example of the Difference Score Approach in attentional orienting?
Cueing Scores from Cueing Paradigm
- reaction time is compared with VALID trials to INVALID trials
Everything else but the valid/invalid trial is kept constant so it makes it easy to attribute it to the location of the cue to target
RT of valid trial - RT of invalid trial = cueing difference score
What is the difference score in the Attentional Blink?
RT + accuracy on T2 on single task trials - dual task trials
= attentional blink (difference score)
Easy to attribute difference from the two conditions to the attentional requirement of having to find T1 and not error variance