varis/correls

• independent variable 


  the variable that the psychologist changes/manipulates
• dependent variable


  the variable that is measured - to see if it has changed e.g. number of words recalled from a list of 20
• operationalisation


  the researcher must make sure the IV and DV are operationalised; this means that they are both specific and measurable. this will allow the researcher or someone else to repeat the study in the same way to check results. for example if we wanted to measure intelligence, we might opertionalise that by saying the DV is the participants score on an IQ test
• extraneous variables 


  variables that could affect the DV (what you measure) if they are not controlled, for example if you are testing people's memory then any background noise could be distracting, or if the room is too hot or too cold which could alter people's behaviour
• variable


  something that can change/vary
• standardisation


  keeping as many aspects of the study the same for participants across groups as possible. this means potential extraneous variables won't impact on one group-participant more than the others
• one method of controlling extraneous variables is standardisation
• repeated measures design


  one way to avoid participant variables is to use the same group of participants for every condition (every IV change) so that you can compare the same people. this means their IQ, gender, background etc are all the same throughout.
• confounding variables


  a type of extraneous variable that varies systematically with the independent variable.
• difference between extraneous variables and confounding variables

  the confounding variable has a relationship with the IV (what we measure) and as the CV increases, so will the IV.

  the extraneous variable has no relationship and will change randomly between participants.
• examples of specific participant EVs


  height/weight

  age

  sexuality/gender

  religion

  eyesight

  mental health

  memory issues
• investigator effects (experimenter variables) can be overcome by using a double-blind technique. this is when a person who carries out the research is not the person who designed it, and does not know what the aim of the experiment is
• three types of Extraneous variables

  1. situational variables
  2. participant variables
  3. experimenter variables
• situational variables - anything to do with the environment of the experiment. e.g. time of day, temperature, noise levels
• participant variables - anything to do with the differences in participants. e.g. age, gender, intelligence, skill.
• investigator variables - anything to do with the behaviour and language of the experimenter and how that might influence participants' behaviour (demand characteristics)
• the way in which an experimenter asks a question might act as a cue for the participant. also known as an experimenter bias
• situational variables can be overcome by the use of standardised procedures which ensure that all participants are tested under the same conditions
• participant variables can be completely removed by using a repeated measures design (the same participants used in each condition)
• participant variables can be removed using matched pairs (participants in each group are matched based on ability, skill or age)
• investigator effects can be overcome by using a double-blind trial technique. this is when the person who carries out the research is not the person who designed it, and is unaware of the aim
• participant effects - participants are aware that they are in an experiment, and may behave unnaturally
• "screw you" effect - the participant goes against the experimenters aim and deliberately acts in a way which spoils the experiment
• positive correlations: both the IV and DV increase or decrease at the same time E.G. test scores go up as amount of revision goes up
• negative correlations: the IV increases and DV decreases. E.G. test scores increase as amount of stress decreases
• revision or no revision

  difference
• amount of revision

  correlation