Lecture 5 - RICC

The case of phantom Limbs

Prof. Vilayanur Ramachandran Center for Brain and Cognition

The phantom limbs that couldn’t move can move after the trick with the mirror box. The brain can adapt.

Case studies

The intensive, in-depth examination of a single instance or case

• A rich source of ideas for theory building and can be used to falsify theories

The problem with case studies is that it doesn’t give us a lot of information about the general population, you cant generalisation because there is not a random sample. You observe extreme casus because there informational rich.  You find ways to prove theories wrong, if one case does this; the theory is wrong and needs to be changed (falsification).

Single-variable research

• Census
  • difficult to do, but easy to describe: A body of data collected from every member of the population of interest (only conducted infrequently and by the government; extremely costly)
• (Population) Survey
  
  • The study of a subset of people in the population of interest
• Random sampling vs cluster sampling (pick 10 city’s/class and pick then randomly)
• Sampling error; margin of error
• Epidemiological research
  
  • A study of the prevalence of a psychological disorder in the population
• Public opinion research
  
  • Marketing research: different polls give different answers due to sampling error (the samples aren’t random selected)

Drawbacks and limitations

• Complex sampling (other ways of asking people)
• Participant scepticism (in the beginning people wanted to help, nowadays you cant go on the internet without asking your opinion about something so people get annoyed)
• Breadth of participant
• Backgrounds and research setting

Multiple-variable research

• Correlational methods
  • Measure a number of different variables in a representative sample and determine the associations between them
• Very susceptible to confounds

Depression is associated with a negative self image. Depressed à bad self image

Suggest you find that indeed a high rate on depression score with a low rate on self image. But it could be something else that leads to both of them. It’s a confound / third variable problem.

Limitations

• Confounds
  • Person confounds: internal for the participants
  • Environmental confounds: for example covid-19, external
  • Operational confounds: when the test measures more things. For example: not only measures depression but also anxiety.
• The problem of reserve causality: does A causes B or does B causes A?

Experimental Methods

The experiment

• Manipulation
  • Systematic change to the levels of the independent variable
  • If this leads to corresponding changed in the dependent variable à cause and effect
• Random assignment
  
  • Matching, make groups/pairs the same (identical on some factos; age, gender, ses) before taking the experiment. Min. 20 participants per group, otherwise you cant generalize.

Strengths of True experiments

• They eliminate individual differences
• They eliminate confounds (but not al)
• They allow us to observe the invisible (variables that are hard to see; invisible learling)
• They provide information about statistical interactions
• They minimise noise

Are true experiments real?

• The problem: artificiality
• The solution: two forms of realism
  
  • Mundane realism: things appear like they do  in real life (people know they are in an experiment but it looks real).
  • Experimental realism: you can do it on a computer (Milgram experiment)
• Tradeoffs between internal and external validity

Summary

• Non-experimental research: case and individual studies
• Experimental research