Artificial nature of set-up - results may not reflect ‘real-life’ behaviour - reducing the external validity of the study. Participants know they are being tested so may change their behaviour (demand characteristics). Tasks given in the research may not be reflective of everyday tasks (lack of mundane realism).

Establishes cause and effect because extraneous variables are controlled.
Research can be easily repeated as there will be a controlled, standardised procedure, increasing the reliability of the results

HIGHER mundane realism than lab experiments - higher external validity. Often participants won’t know they are being studied, so demand characteristics are less of an issue.

Harder to control extraneous variables - harder to know if the IV has affected the DV. Participants are unaware they are being studied - raises ethical issues (lack of informed consent).

IV is based on an existing difference between people. For example, gender differences in attitudes towards food.

CAN be tested under controlled conditions (as in the example above), increasing the scientific credibility of the research.

PARTICIPANTS can’t be randomly allocated to conditions, introducing possible confounding variables.

Independent variable occurs naturally, not manipulated by researchers

HIGH external validity, as the IV is naturally occurring. The effects can be tested of factors that could not be manipulated by the researcher (e.g., the effects of lack of attachment in Romanian orphans).

Less control over extraneous variable than field experiments. Participants can’t be randomly allocated to conditions, introducing the possibility of bias. Naturally occurring IVs may be rare, so studies can’t be repeated.