Demand Characteristics

Presence of demand characteristics in a study suggest that there is a high risk that participants will change their natural behaviour in line with their interpretation of the aims of a study, in turn affecting how they respond in any tasks they are set.

Participants may, for example, try to please the researcher by doing what they have guessed is expected of them.

Alternatively, they may deliberately try to skew the results in one way or other, such as attempting to do the opposite of what they think is expected (i.e. the 'screw you' effect).

A repeated measures study design is more likely to present the problem of demand characteristics, as participants will be take part in all conditions of the experiment, which could give them enough information to consider the ‘real’ purpose of the study. Independent groups and matched pairs designs are generally at lower risk, as participants will not perform more than one condition of the experiment, so will be less likely to look into the study’s aims. Observational studies are also generally less likely to present demand characteristics, as participants might not know that they are taking part in a study.

Hawthorne Effect

The Hawthorne effect is present when the increased attention given by the researchers is a confounding variable in a study. Evaluation apprehension (i.e. the modulation of arousal and thus performance through participants knowing they are being appraised by others), may lead to a participant trying harder than they usually would do, thus distorting the results collected.

Detecting this effect requires information about similar activities carried out when the participants did not know they were under investigation.

Social Desirability Bias

This bias in participants’ behaviour occurs when they note aspects of the study that have to do with particular social norms or expectations, and in turn present themselves in what they deem a socially acceptable fashion.

For example, when asked if they have ever stolen anything, participants may lie in order to avoid presenting themselves in a bad light, consequently leading to gathering inaccurate data.