Detailed and comprehensive revision notes for the Research Methods component of Psychology A-Level (Edexcel). Packed with ALL the content you need to pass this unit. Methods and statistics simply described for easy understanding! Well-formatted and easily adaptable to add your own notes. Great for ...
Research
Methods
Experimental Method
EXPERIMENT: deliberate manipulation of IV to see what effect it has on DV, aims to
try to determine a cause + effect relationship, tries to keep all other variables
constant
Strengths Weaknesses
Laboratory High level of control Lack ecological validity
allows replication = (artificial setting unlike real
Experiment should give high life) so ppts do not behave
Under controlled reliability – easy to repeat naturally = can be difficult to
conditions All other variables generalise results to other
Artificial environment controlled, so any change situations
IV manipulated + in DV must be caused by Ppts aware they are being
effect on DV measured manipulation of IV (cause experimented on – may alter
e.g. Milgram + effect relationship can their behaviour (display
be determined) demand characteristics)
Field High ecological validity – Low reliability: researcher
ppts in natural cannot control environment
Experiment environment + situation completely, so difficult to
In ppts’ natural likely to reflect those in replicate study to check
environment real life consistency of results
IV is manipulated + Ppts may not know they Lack of control extraneous
effect on DV measured are participating in a + confounding variables could
e.g. Bickman study – less likely to affect the DV, reducing
display demand internal validity
characteristics
Natural Allows research where Random allocation of ppts
the IV cannot be into conditions not possible –
Experiment manipulated for ethical or may be uncontrolled
IV not manipulated practical purposes confounding variables
(changes naturally), Allows researchers to reducing internal validity
effect on DV measured. study real life issues – Very difficult/impossible to
e.g. Charleton et al (St high ecological validity replicate – exactly same
Helena) – studying conditions unlikely to reoccur
aggression before and + difficult to find situation
after the introduction Ethical issues: no informed
of TV in a culture consent
Quasi Can be carried out under Random allocation of ppts
controlled conditions – into conditions not possible –
Experiment can be replicable + may be uncontrolled
Can be in lab/natural
, setting extraneous variables can confounding variables
IV varies due to being be controlled reducing internal validity
a characteristic of ppts
– cannot be
manipulated
e.g. Sheridan and
King?
Experimental Variables
IV: the one the experimenter manipulates, different variations of IV = conditions of
experiment
DV: the variable the experimenter measures to see whether the IV had had any effect
on it
Operationalising Variables
o Making a variable clear/unambiguous
o Process of devising a way of manipulating/measuring something so another person
knows what has been done
o Allows study to be replicated
o e.g. Students will recall more words correctly when tested at 9.00am than when they
are tested at 2.00pm.
Extraneous and Confounding Variables
Extraneous variable: any variable other than the IV which could affect the DV
Might/will have an effect on the IV
Need to be controlled so they stay constant across all experimental
conditions/between ppts
Uncontrolled extraneous variables become confounding variables
Means firm conclusions cannot be drawn about cause + effect
Confounding variables have an effect on the results + confound the DV
Ways to control extraneous variables and prevent confounding variables from
affecting the results:
Standardisation – all ppts should have exactly the same experience (ensure
procedures are standardised: instructions given to ppts exactly the same, stimulus
shown in same way/exactly same length of time)
Randomisation – if two different conditions, ppts should be randomly allocated to
ensure ppt variables do not become confounding variables. E.g. computer
programme/hat (no system) – ppt variables should be evenly spread across conditions
Counterbalancing – if ppts doing all conditions, half should do condition 1 first and
half should do condition 2 first = avoids order effects (e.g. improve in condition 2 due
to practice) – results then averaged.
Controlling Variables
Extraneous Variables
, In an experiment, ideally all extraneous variables should be controlled so effect of
the IV on the DV not distorted/obscured.
Situational Variables
- Environmental factors, can distract ppts’ performance, so influence the measurement
of the DV
- E.g. high noise levels can influence performance in both conditions, but more noise
in one condition may completely distort/obscure the effect of the IV
- Controls (e.g. limiting distractions by testing every ppt in quiet, comfortable lab
conditions) used to prevent extraneous variables becoming confounding variables
- Other controls can be put in place to limit effects of extraneous variables
- All ppts in a condition must have same experience (standardised procedure,
instructions, materials and timing)
Participant Variables
Individual differences of each ppt (e.g. level of intelligence, motivation, attention,
memory ability)
May affect performance and measurement of DV
If different kinds of ppts used in each condition (e.g. independent measures design),
may be unclear whether it is the ppt variables or changing the IV that is responsible
for results
Controls (e.g. random allocation to each experimental condition of an independent
measure design) should balance out ppt variables between the two conditions
Repeated measures designs: ppt variables do not cause a problem (same ppts do all
conditions)
Matched pairs design: conscious effort to reduce ppt variables (pairing ppts with
similar ppts in the other group)
Sample Bias
- Sample should be representative of target population
- Not guaranteed, incl. random sample (esp. if target pop. contain minority groups
who do not get in sample)
- Solution: analyse characteristics of the target pop. + select sample with same traits
(stratified or quota sampling)
Demand Characteristics
Ppts might read things into the situation and start changing their behaviour to what
they believe the situation expects them to show.
Ppts may worry about being in a psychological study/want to appear ‘normal’ –
may change their behaviour/behave in ways they would not normally
Ppts may try to guess what investigation is about (e.g. aim), then behave the
way they think investigator wants them to (Hawthorn effect) or deliberately try
to behave in an unexpected way (screw-you effect)
Ppts might try to ‘look good’ (social desirability), behave out of character or
not tell the truth (problem for questionnaires on sensitive issues)
Hawthorn study – reduced lighting, made temperature better and slowed conveyor
belt expecting workers to be more productive, but they realised what was going on
and worked slower.
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller lottieanstee. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $15.96. You're not tied to anything after your purchase.
