ExperimentsPsychology

Laboratory Experiment

• Conducted under a tightly controlled environment, where the independent variable is directly manipulated by the researcher and the effect of this change is measured by the dependant variable.

• To be a true experiment, the participants should be randomly assigned to the experimental condition

Extraneous Variables

Within an experiment the researcher always aims to manipulate the IV and measure the DV and exclude all other variables that may affect the results. (Other than a natural experiment where the researcher doesn’t manipulate the IV).

EV cont

If the researcher fails to exclude all other variables (extraneous variables) this will mean that it’s not just the IV that affected the DV and this will decrease the validity of the study.

Extraneous variables can be situational or participant.

A situational variables is any variable within the environment of the study which may affect the DV i.e. temperature, noise, other participants in the room

Participant variables are any variables to do with the participants within the study that may affect the DV i.e. mood of participants, age, general health

Experimenter Effects

Experimenter effects are cues or signals from the researcher that can influence the participant’s response. These cues or signals can sometimes be deliberate attempt to influence the participants or unconscious. Examples of experimenter effects could be: how the researcher is dressed

Demand Characteristics

This is where participants guess the aim of the study and change their behaviour to either go against the way they think the researcher wants them to behave or behave in a way that they think the research wants them to behave.

Known as the screw you effect or the please you effect

Field Experiment

Natural environment but the experimenter is still manipulated the independent variable but does so in an environment which is typical of the behaviour being studied.

Natural Experiment

Conducted in a natural environment. The difference is that the IV is not manipulated directly by the researcher. Instead, the researcher takes advantage of a naturally occurring situation where the variable is changed for one group but not another.

For example, Charlton (1998) was able to describe the effects of television on children when it was introduced to the Island of St. Helena.

Sorting Task

Sort each experiment correctly and then discuss