Week 3 - Research Methods in Behavioural Pharmacology Flashcards
What is a between-subjects design?
• Experiments conducted with 2 (or more) different groups
o IV operationalized as different groups
• Usually interested in the difference between the means of these groups
What are the advantages of a BS Design?
- Easier and more time efficient to run
* Allows observation of variables that are not stable (i.e. habituation, practice effects)
What are the disadvantages of BS design?
• Many variables are unable to be controlled (e.g. systematic differences between the groups_)
o Need more participants so these effects average out
• Results are presented in terms of group differences; masks change within the individual
• Method of allocating to groups (randomized controlled trial; consecutive case design?)
What is a within subjects design (repeated measures)?
• Same participant involved in every level of the experiment
o IV is operationalized as different levels/testing occasions that all participant receive
What are the advantages of a WS design?
- Requires fewer participants
* Each participants acts as their own control
What are the disadvantages of a WS design?
- Not amenable to measurement of unstable variables
- Time and money
- May need alternate forms to assess DV to counteract practice effects
- May need to counteract cross-over effects
What are control groups, and what are they used for?
- Used to ensure the effect observed is due to the variable we manipulated and not some other variable
- Especially important in between-subjects designs
- A control group will be identical to the groups being tested, except for the manipulation
What is a placebo and what are they useful for?
- A placebo control conditions similar to experimental condition, except rather than receiving the drug (or no drug) they receive a substance containing no active ingredients (a placebo)
- Placebo controls are extremely useful for investigating whether any benefits derived from a drug are due to placebo effects
What is the Nocebo Effect?
if the side effects told to be negative then can start to actually experience them
What is the expectation mechanism hypothesis?
hypothesized that you need the priming of pain reduction to actually experience pain reduction
What is a three groups design?
- Given a new drug
- Given a proven drug
- Given a placebo
What does a three groups design allow?
- allows a comparison between new drug and placebo
- allows comparison between new and established drugs
- allows experimenter to see if measures are sensitive enough to detect change (i.e. compare proven drug and placebo)
What are alternative combinations of groups used to answer questions of?
o Effectiveness of drugs vs. non-pharmacological interventions
E.g. CBT group vs. drug-treated and placebo-groups
o Specificity of drug effects:
E.g. include groups comprising people with different mental illnesses
• Does the drug work in depression exclusively?
How else may effects be assessed?
over time (multiple measurements (longitudinal design) or once-off (cross-sectional design)) Sources of Bias
What are some sources of bias
o Experimenter and participants expectations/bias (double blind studies) o Selection bias: experimental controls Demographic differences (age/gender) Cultural differences Personality differences Education ect
What is the level of control for experimental designs from low to high?
Introspection -> Naturalistic Observation -> Case History -> Survey -> Test -> Correlation -> Experiment
What are potential variables?
• Depending on the drug and its action, some of the domains in which we may look for effects are:
o Arousal
o Cognition
o Perception
o Motor function
o Mood
• We might also want to measure side effects/biochemical or physiological drug effects
What is the outcome of more performance measures?
• The more measures we use:
o The more comprehensive our assessment
o The more costly our experiment (financial and time)
o The greater the need to consider experimental controls and logistics (e.g. order we administer measures)
What does assessing change in performance across domains tell us?
tells us something about how the drug works, and the effects it produces (primary and side effects)
What are the levels of arousal from low to high?
Death -> Coma -> Sleep -> Drowsy -> Normal -> Aroused -> Highly excited -> mania -> convulsions -> death
What is one brain scanning way to measure arousal?
• EEG: a measure of arousal/detects potential differences between points on the scalp and neutral points on the body
What are other ways to measure arousal?
o Introspection?
Unstructured introspection
Systemic introspection
o Ask an observer?
How to measure mood?
• Can be studies experimentally (e.g. we can test drug effect by inducing mood states) or using a b-g design (e.g. depressed vs. non-depressed patients)
• Measurement could be by self-report, doctor’s assessment, informant report, questionnaire, tests of biological markers of depression etc.
o Consider the adv and dis of these ways of assessing drug effects on mood
What does perception research study?
- Perception research often investigates the changes in the sensitivity of a person’s perception brought about by changes in the internal or external environment (e.g. drug use)
- Changes in sensitivity = thresholds (two types)
