We often assume that psychology and neuroscience experiments tell us general things about how humans think and behave, but little attention is given to whether the people who volunteer for research studies are representative of the wider population.
PsyBlog has a concise summary of a recent study that looked at the sort of people who volunteer for research studies and how they differ from the general population.
Narcissists are over-represented amongst non-participators, as are those low on assertiveness. On the other hand, those high on obsessive-compulsive, histrionic, self-sacrificing and intrusive/needy measures are more likely to participate.
What is not clear is how these sort of differences affect different types of studies.
For example, will a study that is investigating memory by significantly affected by the fact that the participants are likely to be less narcissistic than the general population?
Link to PsyBlog post ‘Why do people participate in research?’.
Mind Hacks 