laboratory experiment

• key features of laboratory experiments

  • control- laboratory is an artificial environment where scientists can control different variables in order to discover what effect they have
  • the experimental and control group- scientist divides up two groups, one exposed to independent variable + one not exposed and conditions kept constant
  • cause and effect- conditions in group measured, if change is discovered in experimental group a cause and effect relationship is discovered
• practical issues of laboratory experiments

  • open systems- keat argues they are only suitable for studying closed systems where researcher can control and measure all the relevant variables and make precise predictions, society is an open system where countless of factors are at work
• individuals are complex

  • not possible to match the members of the control and experimental groups exactly
  • no human beings are exactly alike
• studying the past

  • cannot be used to study an event in the past as we cannot control variables acting in the past
• small samples

  • laboratory experiments can usually only study small samples, difficult to investigate large scale phenomena
  • bring the risk of chance correlation
• Hawthorne effect

  • artificial environment and any behaviour that occurs may be artificial
• the expectancy effect

  • experimenter bias
  • refers to researcher's expectations may influence experiments outcome
• ethical issues for laboratory experiment

  • informed consent- researcher needs the informed consent of subjects
  • harm to subjects- some argue minor harm may be justified ethically if results yield significant social benefits
• theoretical issues- reliability and hypothesis testingpositivists regard laboratory experiment as highly reliable for 3 reasons:

  1. experimenter can control the conditions and specify the precise steps that were followed in the original experiment- can be easily repeated
  2. produces quantitive data
  3. detached and objective method as subjective feelings and values have effect on the conduct or outcome of experiment
  4. effective way to test hypotheses and predictions
• representativeness

  • laboratory experiments may lack external validity as they may not be true for the wider population
• internal validity of laboratory experiments

  • the artificiality of the laboratory experiment may encourage the hawthorne effect
  • lack internal validity
• interpretivism and free will for lab experiments

  • interpretivists argue human beings are fundamentally different from plants, rocks as we have free will and choice
  • behaviour is not caused by outside forces and actions can only be explained by choices we make freely
  • behaviour cannot be explained in terms of cause and effect relationships
  • lab experiment is fundamentally flawed with its search for a cause