control of variables

• experiments in psychology tend to have either control and realism
• realism is how a study mirrors the real world - research environment is realistic to degree to which experiences encountered in research environment will occur in real world
• control is the extent to which any variable is held constant or regulated by a researcher
• confounding and extraneous variables need to be controlled in order for the researcher to be able to draw conclusions accurately
• confounding variables are those which are not the IV but varies systematically with IV - changes in DV may be due to confounding variables rather than IV (outcome is meaningless)
• extraneous variables do not act as an alternative to IV by may have an effect on the independent variable making it more difficult to detect what has caused the effect
• if an experiment is too artificial then participants will not act as they would normally and so it lacks realism
• mundane realism is the extent to which findings or a theory can be applied to real life
• mundane realism focuses on how applicable findings are in the real world
• factors affecting internal validity:

  • demand characteristics
  • investigator effects
  • participant variables
  • situational variables
• situational variables are factors in environment that can affect the outcome of a research study including temp or lighting
• participant variables are the differences between participants that could affect the results of the study
• demand characteristics are a cue that makes participants consciously aware of aims of study or helps participants work out what the researcher is expecting to find - as result participants changed their behaviour creating inaccurate results for the study
• single blind design is where the participant is not aware of research aims of which condition of the experiment they are receiving and this prevents them from seeking cues about aims and reacting to them having demand characteristics
• experimental realism occurs if the researcher makes an experimental task engaging the participant who then pays attention to the task and not the fact that they are being observed
• double blind design is where both participants and person conducting experiment are 'blind' to aims and hypothesis - therefore person conducting investigation is less likely to produce cues about what they expect
• investigator effects includes anything the investigator does that has an effect on participants performance in study other than what was intended - direct effects such as interacting with the participants
• investigator effects can act as a confounding or extraneous variable within an experiment
• indirect effects are those which are a consequence of the investigator designing the study
• demand characteristics can be solved using:

  • single blind design
  • double blind design
  • experimental realism