(2) Research Issues

• in any experiment there will be unwanted factors which could affect the relationship between the IV and the DV, spoiling or disorting the results in the process
• in experiments, we need to know the manipulation of the IV causes the DV
• the key to an experiment is that an IV is manipulated to see how this affects the DV
• Extraneous Variables :

  • additional unwanted variables that interfere with the IV (or the DV)
  • these variables should be controlled or removed
  • are usually identified at the start of the study by the researcher - takes steps to minimise their influence
• Nuisance Variables :

  • straightforward variables which can be easily controlled
  • they do not vary systematically with the IV
  • eg age of participants or lighting in the lab
  • does not confound the findings of the study
  • make it harder to detect a result (find the task harder)
• The different unwanteed factors in an experiment are :

  • Extraneous variables
  • nuisance variables
  • confounding variables
  • demand characteristics
  • Investigator effects
• Confounding Variable :

  • a type of extraneous variable - not controlled at the start of the experiment
  • external factor in an experiment that affects both the IV and DV
  • can introduce bias or error
  • makes it difficult to determine if the observed effects are only due to the IV
  • controlling of confounding variables are essential to establish true cause and effects relationships
  • if not properly controlled, interferes with the DV
• Demand Characteristics :

  • participants are not passive within the experiment
  • participants try to make sense of the new situation
  • participant reactivity - a significant extraneous variable that is difficult to control
  • clues/cues may help participants interpret the aims of the study - 'second-guess' the experimenters intentions
  • may look for clues on how to behave in the experimental situation - unnatural behaviour
  • may affect the DV
• Demand Characteristics could lead to :

  • please-U effect
  • screw-U effect
• please-U effect = participant act in a way that they think is expected and over perform to please the experimenter
• screw-U effect = participant deliberately under performs to sabotage the results of the study
• Investigator Effect :

  • is any unwanted influence of the investigator on the research outcome
  • could be a result of participant reactivity
  • Coolican (2006) : expectancy effect, unconscious cues, leading questions
• Expectancy Effect :

  • present when someone expects a given result
  • expectations unconsciously affect the outcome of the expected results
  • when participant expects certain kind of outcome, they change their actions and behaviours to get that expected outcome
• Unconscious Cues :

  • subtle, unintentional, unconscious cues - communication that provides information to another individual
  • verbal : speech, patterns, physical activity while speaking or tone of voice
  • non verbal : facial expressions and body language
• Leading Questions :

  • questions that are worded to suggest a particular answer
  • lead to bias
  • eg 'you like it here don’t you’ - invokes a ‘yes’ response
• in any investigation, there are simple steps that the researcher can take to minimise the effect of extraneous/ confounding variable’s on the outcome
• randomisation is an attempt to control investigator effect (error and bias)
• randomisation = the use of chance wherever possible to reduce the researcher's influence on the design of the investigation
• randomisation = standardised procedures
• in an experiment which involves a number of different conditions, the order and the participants should be randomly determined (randomised)
• in a randomisation, a random number generator could be used
• Standardisation :

  • all participants should be subject to the same environment, information and experience
  • standardised instructions are read to each participant in the experiment - followed by everyone
  • means non standardised changes in the procedure do not act as extraneous variables