Laboratory experiments

Conducted

In a highly controlled environment

Not always an actual scientific laboratory

A lab is any place where conditions can be well controlled

Only lab and field experiments are true experiments because the independent variable is manipulated 

Strength 1

Have high control over extraneous variables - means that the researcher can ensure that any effect on the dependent variable is likely to be the result of the manipulation of the independent variable - leads to high internal validity as we can be more certain about demonstrating cause and effect relationship

Strength 2 

Replication is more possible because of the high level of control - ensures that new extraneous variables are not introduced when repeating the experiment 

Replication is vital to see whether the findings are valid 

Limitations 1

May lack generalisability - lab environment may not reflect everyday life therefore participants may behave in unusual ways - means that the behaviour can not always be generalised - low external validity

Limitation 2

Participants are usually aware they are being tested and this may give rise to unnatural behaviour (demand characteristics)

Tasks participants are asked to carry out in lab experiments may not represent everyday experience- therefore it has low mundane realism