experiments Flashcards
what are the purposes of experiments?
they involve the manipulation of an independent variable to see its effect on the dependent variable
what are the three types of experiments?
- laboratory
- field
- quasi
what are laboratory experiments?
an experiment in an controlled environment, all other variables (extraneous variables) are controlled an kept at a constant
what are positives of laboratory experiments?
- high control
- reliable
- replicable
- standardized procedures
- control EV’s
= increases internal validity
what ae negatives of laboratory experiments?
- decreases ecological validity
= artificial environments
= demand characteristics
what are field experiments?
the experiment takes place in a natural environment e.g a participant’s home
what are positives of field experiments?
- increases ecological validity
= natural environments
= low in demand characteristics
what are negatives of field experiments?
- low control
= decreases reliability - EV’s may affect behavior
- lack of consent
what are quasi experiments?
an experiment where the ‘IV’ is naturally occurring and not manipulated by the experimenter e.g hair colour or eye colour
what are some positives of quasi experiments?
- you are able to investigate participants that would otherwise not be able to be investigated as i would be impossible or unethical
what are some negatives of quasi experiments?
- it may be difficult o gather participants sometimes
which is the ‘cause’ IV or DV?
IV
which is the ‘effect’ IV or DV?
DV
what are extraneous variables?
factors that can affect the behavior of participants
e.g light, noise or heat etc.
or emotional state of participants, sex, age etc.
what are cofounding variables?
when extraneous variables ‘align’ themselves with he experimenter’s manipulation of the IV, they become cofounding variables
what is meant by experimental control?
preventing extraneous variables from becoming cofounding variables
what is a hypothesis?
a testable statement based on theory or observation, a prediction of the relationship between 2 variables, a prediction of the ‘cause an effect’
what is an experimental (alternative) hypothesis?
this type of hypothesis tests the cause of independent variable on the effect of dependent variable
what are the two types of experimental/alternative hypothesis?
directional (one-tailed)
non-directional (two-tailed)
what is a directional hypothesis?
this hypothesis predicts the direction in which the results are expected to occur e.g ‘significantly more/less’
what is a non-directional hypothesis?
this hypothesis doesn’t predict the expected direction of e outcome, but will state that there is a difference between the two states, the hypothesis does not specify if the behavior will be better or worse, just different
what is a null hypothesis?
the counterpart to the experimental/alternative hypothesis.
‘no difference’ ‘no change’
if the null hypothesis can be rejected statistically, we can accept the experimental/alternative hypothesis
what is experimental designs?
the researcher must decide whether the same participants will be tested in both conditions, or whether different participants will be tested in different conditions
what does two levels of the IV mean?
two or more conditions in an experiment
what is independent measures?
using different participants in each of the experimental conditions, the two groups will be exposed to different kinds of treatments. by comparing the performance from each group, you will be able o establish where the IV affects participants behavior.
what are positives of independent measures?
- no order effects
- high in validity
= only experienced one IV - cost and time effective
what are negatives of independent measures?
- more participants involved
- low levels of individual differences
= some people may have different abilities
= lo in validity
what are repeated measures?
comparison of people in one condition with their own performance in another condition, the same participants for both conditions.
what are the positives of repeated measures?
- less participants
- reduces time and cos
- high levels of individuality differences
= increases validity - can use the same task in all conditions
= increases validity
what are the negatives of repeated measures?
- participants have experienced both conditions of the iv, so hey either already have an advantage or the will become bored
= decreases validity
what are matched pairs?
the experiment matches individuals in either condition to another in the other condition e.g from their height, age or gender
what are positives of matched pairs?
- high control over individual differences
= increases validity - can use the same task in all conditions
= increases validity
what are the negatives of matched pairs?
- time consuming
= you have to match participants - can be subjective in the choice of matching criteria
how to prevent order effects?
counterbalancing, sample divided in half and he order is changed
e.g A B A B A B
= order effects balanced
12 marker structure?
what - define in one sentence
how - include as much replicable detail as you can (contextualise it)
justify - why have you chosen to use this particular feature (give a strength in context)
link - link it back to your own study that you did in your practical (explain why you are now doing a certain feature in this experiment)
what should you do first in your 12 marker?
find the dv, and find the two levels of the IV
what is in MB4 for the 12 marker?
- 3 x RFs
- accurate and detailed knowledge and understanding of A01
- context
- appropriate justifications and contextualised
- good PEC
- reference to your own link
what experiment did we carry out?
whether it was easier to remember words or pictures more?
