Psychology Experiments

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  • Created by: Gemma
  • Created on: 29-09-12 21:59

Natural Experiment

Description: Carried out in a natural environment where the experimenter makes use of an existing situation and record peoples reactions. The IV and any extraneous variables cannot be controlled (the IV for practical or ethical reasons) and the participants cannot be selected by the experimenter as the situation is naturally occurring.


  • Participants do not always know they're being watched so they behave naturally.
  • High ecological validity and mundane realism* because they are real-life situations.
  • Investigates the effects of independent variables that may be unethical to manipulate.


  • Any extraneous variables will reduce the validity because they cannot be controlled.
  • Requires ethical sensitivity.
  • Hard to identify what aspects of the IV may have caused the results (cannot determine cause and effect).

*the extent to which it mirrors the real world

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Laboratory Experiment

Description: Carried out in a controlled setting where participants know they are being studied.


  • High internal validity, extraneous variables can be controlled so cause and effect can be established.
  • Uses standardised procedures so experiment is more reliable (anyone can repeat it). 
  • Increased control of all variables and accurate measurement.


  • Artificial setting may produce unnatural behavior which means low ecological validity.
  • Low mundane realism, the experiment does not mirror the real world.
  • Participants may display demand characteristics if they know they are being studied.
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Field Experiment

Description: Carried out in a natural environment. Setting is not controlled, it is real life. Full control of IV but participants are unaware of being studied.


  • More natural behavior from participants because they are unaware of being studied.
  • Higher ecological validity than lab experiment because the setting is not artificial.
  • Higher mundane realism because of natural environment.


  • Low internal validity because you can't establish cause and effect.
  • Harder to control the extraneous variables.
  • Major ethical issues because people are unaware of taking part, no consent.
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Correlational Analysis

Description: The relationship between two variables can be positive, negative or no correlation. They use scatter diagrams to represent the information, mostly they are linear but can also be curvilinear. They have a correlation coefficient number between -1 and 1, -1 being strong negative correlation and 1 being strong positive correlation. 0 means no correlation.


  • Can be used when it is unethical to manipulate the variables.
  • If a strong correlation is found it means further investigation is justified to find a cause and effect.
  • Easily repeated.


  • Often misinterpreted, might be two things which seem to have a relationship but don't. For example ice creams eaten and hay fever sufferers.)
  • Lack of correlation may not mean there is no relationship, it could be non-linear.
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Description:  Set of questions to interpret data, can be open or closed. Open means you can write whatever you want in the answer box, closed means there is a choice of answers for you to pick.


  • Easily repeated. (both)
  • Not predicted answers. (open)
  • Specific answers. (closed)
  • Cheap to produce. (closed)


  • Not detailed enough or too detailed. (open)
  • Not necessarily relevant. (open)
  • Variety of answers may be too wide. (open)
  • Answers cannot be expanded. (closed)
  • Social desirability bias (people may write what they think you want to hear).
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Description: A face to face questionnaire. A structured interview has planned questions and an unstructured interview asks questions based on previous answers. i.e doctors app.


  • Standardised questions are easily repeated. (structured)
  • answers more predicable and easier to analyse. (structured)
  • More detailed answers because questions asked depending on answers. (unstructured)


  • Expectation of interviewer influences answers, interviewer bias.
  • Reliability changes depending on interviewer age, gender, race etc.
  • Need a well trained interviewer to make up on-the-spot questions. (unstructured)
  • Developed questions may be less objective. (unstructured)
  • Time consuming. (unstructured)
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Description: Behavior is studied, in a natural observation its in a natural environment, in a control observation some variables are controlled and the participants are aware they are being observed.


  • Data gathered is reliable. (control)
  • Participants unaware of being observed. (natural)
  • Cheaper. (natural)


  • People may feel uncomfortable being watched. (control)
  • High demand characteristics. (control)
  • May happen at odd times and be inconvenient. (natural)
  • Subject to interruptions, extraneous variables. (natural)
  • People don't know they are being watched, no consent. (natural)
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