something that a researcher changed or manipulates
in order to test the affect of IV we need different experimental conditions and we need a comparison
what is the dependent variable?
the variable that is measured by the researcher.
any effect on the DV should be caused by the IV
a well written hypothesis should make it easy to tell what the IV and DV are
operationalization of variables :
we have to operationalise variables to make it testable so it needs to be very measurable, therefore very clear
e.g use numbers (300ml) and names (lucozade)
extraneous variables:
any variables ,other than the IV, should be be controlled or removed as it can affect the dependent variable
unwanted, extra variables
are identified before the study by the researcher, who takes steps to minimise their influence
most are straightforward to control e.g age and lighting, but some so not vary systematically with the IV
what are the two types of extraneous variables?
participant variables
situational variables
what are participant variables?
any individual differences between participants that could affect the DV
what are situational variables?
any features of the experimental situation that may affect the DV
what variables are these examples of:
age
personality
motivation
intelligence
participant
what variables are these examples of:
noise
time of day
temperature
weather
situational
confounding variables:
they change systematically with the IV
we cannot tell if there are any changes in the DV and if it’s due to the IV or confounding variables - can become an unintentional IV
variables you find after the study that can influence the DV
application to marshmallow test: participant variables
if the child is used to waiting for things normally
if they have a sweet tooth
if they were hungry or had eaten something previously
application to the marshmallow test: situational variables
ensure they are tested in the same room
demand characteristics:
participants are not passive within an experiment and are likely to spend a lot of the time trying to make sense of the situation
this is a significant extraneous variable in experimental research and is very difficult to control
cues may help ppts figure the aims of the study
as a result, they may act in a way they think is expected and over-preform (please U effect) or they may act in a way to sabotage the study (screw U effect)
therefore the behaviour is unnatural
investigator effects:
things that you do that could influence the participants of the behaviour
for example, if the researcher is smiling more at a certain participant, it may encourage behaviour, and cause the please U effect
it refers to the unwanted influence of the investigator on the research outcome
randomization:
in an investigation a researcher can take simple steps to minimize the effect of extraneous/confounding variables on the outcome
randomization= use of chance methods to reduce the researchers unconscious bias when designing an investigation (attempt to control investigator effects)
standardization:
all participants should be subject to the same environment, information and experience
to ensure this , all procedures are standardized, so a list of ectactly what should be done in the study
e.g standard instructions to read to each ppt, so that there are no extraneous variables