definitions

• types of extraneous variables

  situational variables, participant variables, investigator variables
• situational variables


  due to the environment (e.g noise)
• participant variables

  due to the participants background (e.g likes and interests)
• investigator variables


  due to behavior exhibited by the investigator, unconsciously conveying experimenter bias (e.g being rude to a participant)
• demand characteristics 


  unnatural behavior as a result of cues from the researcher or situation, which are interpreted as revealing the purpose of the experiment. could cause social desirability bias, and affect results.
• social desirability bias 


  answering in a manner that will be favorable by others (e.g telling your doctor that you exercise 5x a week, rather than the actual amount of 3x)
• social desirability bias (simple)


  giving people the answer you think they would like to hear
• investigator effects


  effect of investigators un/conscious behavior (e.g design of the stud, selection and interaction with participants)
• randomisation


  the use of chance, to control the effects of bias (e.g when making decisions, designing order and conditions)
• standardisation


  ensuring everything is the same- formalised procedures and instructions for all participants (e.g everyone takes the same memory test)
• mundane realism


  measure of external validity. recording the extent to which experimental findings can be generalised for the real world
• mundane realism (simple)


  how natural an experiment seems, and how close it is to real life
• the pilot study (simple)

  a practice version
• the pilot study


  small scale version to allow a researcher to test run and modify if necessary before the experiment takes place
• pilot study- self report


  surveys and interviews, questions can be trialed in advance to remove or reword any ambiguous questions that may cause confusion
• single blind procedure


  only doctor knows the aim of the experiment, to control confounding effects of demand characteristics
• double blind procedure

  doctor and patients are unaware of the aim of the experiment, an independent individual only knows which is real and placebo
• placebo


  a substance with no therapeutic effect, used as a control
• extraneous variable


  all variables other than the independent variable- need to be controlled
• confounding variable

  type of extraneous variable that can't be controlled. produces an unwanted effect on dependent variable and distorts findings by obscuring the effect of the independent variable
• quantitative data

  numerical basis (e.g stress ratings)
• qualitative data

  non numerical, narrative or descriptive form (verbal, reports)
• experimental methods

  researcher always intervenes directly by manipulating the situation, one variable is always changed (IV)