A form of experimental sabotage where the research participant does not want to conform to the experiments' demands. When a participant is in an experiment you may not get accurate results because they are aware of the experiment and in turn go out of their way to do everything wrong or go against everything you ask them to, in essence, they may deliberately try to ruin the experiment (the "screw you effect"; Masling 1966). In Psychology, demand characteristics refers to when a person changes his/her behaviour because he/she is in an unfamiliar situation, carrying out artificial tasks and tries to make sense of this by 'working out' what the researcher wants. After 'working out' what the researcher wants, he/she will either try to 'please' the researcher by doing what he/she thinks the researcher wants them to do (known as the please you effect) or go against what the researcher wants by doing the opposite of what he/she thinks the researcher wants them to do (known as the 'screw you' effect).
For example, the children in Bandura's (1966) study of TV violence and aggression may have punched and kicked 'bobo dolls' because they thought that the study was a 'game' and that this was what Bandura wanted them to do (please you effect), rather than because they'd previously watched an adult punching and kicking the dolls on a video, as Bandura argued (i.e. it wasn't the video that caused the aggression but the expectations of Bandura).
