Experimental Design 1

You have one sample of participants that receives each condition of an experiment.

• 2 x 2 Factorial design

• Repeated measures design

• Independent samples design

• Matched pairs design

Each participant is compared to him or herself. Participant variables are therefore controlled.

• 2 x 2 Factorial design

• Repeated measures design

• Independent samples design

• Matched pairs design

A limitation may be that it is not possible to use the same materials. For example, you cannot use the same list of words to memorize under two conditions. By using two different lists of words, you now have introduced a confounding variable.

• 2 x 2 Factorial design

• Repeated measures design

• Independent samples design

• Matched pairs design

The sample is randomly allocated to one condition of the experiment.

• 2 x 2 Factorial design

• Repeated measures design

• Independent samples design

• Matched pairs design

This was used by Loftus & Palmer (1974). The participants were randomly allocated to receive one of the questionnaires. They were not asked the question with each verb (smash, hit, collide), but only one.

• 2 x 2 Factorial design

• Repeated measures design

• Independent samples design

• Matched pairs design

Order effects are controlled for since each participant only experiences one condition.

• 2 x 2 Factorial design

• Repeated measures design

• Independent samples design

• Matched pairs design

An independent samples design in which participants are not completely randomly allocated to conditions. Instead, they are usually pre-tested with regard to the variable.

• 2 x 2 Factorial design

• Repeated measures design

• Independent samples design

• Matched pairs design

A study that used this design investigated Social Learning Theory. Bandura (1961) allocated the children to conditions, matched for their level of aggression.

• 2 x 2 Factorial design

• Repeated measures design

• Independent samples design

• Matched pairs design

This design involves more than one independent variable.

• 2 x 2 Factorial design

• Repeated measures design

• Independent samples design

• Matched pairs design

Abrams et al (1990) used this method to study the role of social identity on conformity. His first IV was whether the confederates were in the participants' in-group or out-group. The second IV was whether the participants' response was public or private.

• 2 x 2 Factorial design

• Repeated measures design

• Independent samples design

• Matched pairs design