Experiments

• Experiments


  In the natural sciences such as chemistry and physics, experiments are used to discover scientific laws of cause and effect
• Laboratory experiment


  The method favoured by natural scientists for discovering scientific laws
• Experimental method


  1. Take a set of identical plants

  2. Randomly divide into experimental and control groups

  3. Treat the groups differently

  4. Measure and record changes

  5. Compare the results
• Independent variable


  The causal factor (e.g. nutrients)
• Dependent variable


  The effect (e.g. plant growth)
• The logic of the experimental method is that the scientist manipulates the variables in which they are interested, in order to discover what effect they have</b>
• By following the experimental method, the scientist can establish a cause-and-effect relationship and predict what will happen in the future under specified conditions
• Experiments


  • Experiment to see whether mice develop cancer when exposed to cigarette smoke
• Sociologists have occasionally used the laboratory experiment as a way of studying human behaviour
• Types of experimental method used by sociologists

  • Laboratory experiments
  • Field experiments
  • Comparative method
• Laboratory experiments


  • Highly reliable, producing the same results each time
  • Researcher merely manipulates variables and records results, personal feelings/opinions have no effect
• Despite the advantages of laboratory experiments, they are rarely used in sociology, even by positivists
• Practical problems with laboratory experiments in sociology

  • Society is a very complex phenomenon, impossible to identify and control all possible variables
  • Cannot be used to study the past
  • Usually only study small samples, making it difficult to investigate large-scale social phenomena
• Ethical problems with laboratory experiments on humans

  • Lack of informed consent
  • Deception
  • Harm to participants
• Milgram's experiments on obedience to authority were criticised for lack of informed consent and causing harm to participants
• The Hawthorne Effect - people may behave differently when they know they are being studied, invalidating the results
• Interpretivist view


  Humans have free will, consciousness and choice, so their behaviour cannot be explained in terms of cause and effect
• Alternatives to laboratory experiments

  • Field experiments
  • Comparative method
• Field experiments


  • Take place in the subjects' natural surroundings, subjects are generally not aware they are part of an experiment
  • Researcher manipulates variables to see the effect on unwitting subjects
• Field experiments are more natural, valid and realistic than laboratory experiments, but the researcher has less control over variables
• Research Methods


  Using experiments to investigate education
• Comparative method


  A thought experiment carried out in the mind of the sociologist, designed to discover cause-and-effect relationships by comparing two groups that differ in one key variable
• Researchers sometimes use experiments to study issues such as teacher expectations, classroom interaction, labelling, pupil self-concepts, and the self-fulfilling prophecy
• The comparative method avoids the problems of laboratory and field experiments, but the researcher has less control over variables
• Many psychologists claim that teachers' expectations of different groups of pupils have important effects, leading to labelling, self-fulfilling prophecy and unequal achievement
• Both field and laboratory experiments can be used to investigate teacher expectancy effects
• These effects can be positive or negative
• Laboratory experiments on teacher expectations

  1. Showing teachers photographs of children from different social class backgrounds

  2. Asking teachers to rate the children on performance, parental attitudes, aspirations etc.

  3. Finding that lower-class children were rated less favourably, especially by more experienced teachers
• Teachers base their ratings on the similarities they perceive between the children in the photographs and pupils they have taught


  This indicates that teachers label pupils from different social classes and use these labels to pre-judge pupil potential
• Teachers' expectations may be passed on to pupils through non-verbal communication


  Researchers found that teachers in the high expectancy group made more eye contact and gave out more encouraging body language than the low expectancy group
• Negative teacher expectations have a much greater impact than positive ones on teachers' predictions of a pupil's end of year attainment
• Laboratory experiments


  • Have fewer ethical problems than those involving real pupils
  • Usually only examine one specific aspect of teacher expectations
• It is impossible to control all the variables that might influence teachers' expectations in real school settings
• Field experiments


  • Located in real educational settings
  • Pose major ethical problems, e.g. the potential impact on pupils, the need for deception
• Rosenthal and Jacobson's Pygmalion in the Classroom study illustrates the difficulties of using field experiments to study teacher expectations
• Rosenthal and Jacobson's study


  1. Gave teachers false information that some pupils were likely to 'spurt' academically

  2. Found that the 'spurter' pupils did in fact make greater academic gains over the following year
• Rosenthal and Jacobson's study raised major ethical concerns, as the 'non-spurter' pupils may have been held back educationally
• Field experiments


  • Work best when those involved are unaware they are in an experiment, requiring deception
• Rosenthal and Jacobson's study design was relatively simple and easy to repeat, but it is unlikely the original could be fully replicated due to differences between school classes
• Rosenthal and Jacobson claimed teachers' expectations were passed on through differences in interaction, but later studies found no evidence to support this