2.1 Evaluate the research methods used in each of the three chosen studies

This guide will help you answer 2.1 Evaluate the research methods used in each of the three chosen studies.

Evaluating research methods means looking at how each study was designed, how data was collected, and how results were analysed. This also involves judging how well the method suited the aims of the research, as well as the strengths and weaknesses of the approach. Here we will assess the research methods used in the three selected studies:

• Milgram’s obedience experiment
• Bandura’s Bobo Doll experiment
• Loftus and Palmer’s eyewitness testimony experiment

For each, we will look at the research design, sampling, controls, measurement of variables, validity, reliability, and ethics.

Milgram’s Obedience Experiment

Research method

Milgram used a controlled laboratory experiment. This allowed manipulation of the independent variable — the presence and authority of an experimenter giving instructions — and measurement of the dependent variable — the maximum shock level participants were willing to administer.

• Sampling: Volunteer sampling through newspaper ads. Participants were all male, aged 20–50, from different jobs and education levels.
• Procedure: Standardised script prompts, same equipment, set sequence of questions, and pre‑recorded learner responses.

Strengths

• High control: The laboratory setting allowed control over extraneous variables, increasing internal validity. All participants experienced the same procedure, making it possible to compare results fairly.
• Standardisation: Same prompts, shock levels, and environment improved reliability.
• Clear operationalisation: Obedience was measured as the voltage level participants reached.

Weaknesses

• Low ecological validity: The artificial setting and task do not reflect most real‑life obedience situations.
• Sampling bias: Only American men volunteered, so findings may not reflect the behaviour of women or other cultural groups.
• Ethical issues: High levels of deception, lack of fully informed consent, and psychological distress challenge the acceptability of the method.

Overall evaluation

Milgram’s method allowed him to answer his research question with clear data and detailed control over conditions. However, the ethical cost and questions about how far findings generalise to everyday behaviour remain strong criticisms.

Bandura’s Bobo Doll Experiment

Research method

Bandura used a laboratory experiment with independent groups. The independent variables were the type of model (aggressive, non‑aggressive, or no model) and consequences of the model’s behaviour (reward, punishment, or no consequence). The dependent variable was the number of aggressive acts shown by the children.

• Sampling: Opportunity sampling — 72 children (36 boys and 36 girls) from a nursery at Stanford University.
• Procedure: Controlled exposure to role models, followed by observation in a room with toys including the Bobo Doll.

Strengths

• High control: Variables such as model behaviour, time of exposure, and toys available were carefully set.
• Replicability: Standardised procedure allows repetition to test reliability.
• Operational measures: Aggression was recorded as physical and verbal acts, giving measurable data.

Weaknesses

• Ecological validity: The setting and novelty toys are artificial and may not match natural play environments.
• Short‑term measurement: The method only measured immediate imitation, so it does not show whether aggression persisted.
• Demand characteristics: Children may have thought they were supposed to copy the adult, affecting behaviour.
• Sampling limitations: Children from one nursery may share cultural and social similarities, limiting wider application.

Overall evaluation

Bandura’s design was strong in experimental control and provided clear evidence for observational learning. Yet the limited sample, artificial setting, and short‑term focus reduce the extent to which the findings can be generalised.

Loftus and Palmer’s Eyewitness Testimony Experiment

Research method

Loftus and Palmer used a laboratory experiment with independent measures. The independent variable was the verb used in the critical question (“hit”, “smashed”, “bumped”, etc.). The dependent variable was the estimated speed and, in a later test, whether participants reported seeing broken glass.

• Sampling: Opportunity sampling of student participants.
• Procedure: All participants watched the same film clips and received the same questions except for the key verb change.

Strengths

• High control: Each participant saw the same scenes and received standardised questions apart from the chosen verb.
• Cause and effect: The clear manipulation of language allowed strong conclusions about the effect of wording on recall.
• Replicable: The simple and controlled design makes repeating the study straightforward.

Weaknesses

• Ecological validity: Watching a film lacks the emotional impact and context of witnessing a real accident.
• Sampling bias: Students may not represent the general public in terms of memory ability or driving experience.
• Artificiality: The questioning context in a controlled setting may not reflect real police interviews.
• Overemphasis on error: The method highlighted inaccuracies without exploring when memory remains reliable.

Overall evaluation

The method gave precise evidence that phrasing affects memory recall. Its simplicity and replicability are major strengths. The main drawback is the artificial setup, which raises questions about how far results can be applied to real‑world eyewitness situations.

Comparative Evaluation of Methods

Across all three studies, the laboratory experiment was the chosen approach. This gave:

• High control over variables
• Replication possibilities
• Ability to isolate cause and effect

Yet all faced criticism for low ecological validity and issues with generalising results beyond the research setting.

Differences between the studies include:

• Milgram used adult male volunteers; Bandura used young children; Loftus used students. This affects how well results apply to other groups.
• Bandura’s was observational in nature, focusing on countable behaviours, whereas Loftus and Milgram both relied on participant responses to staged scenarios.
• Ethical concerns were greatest in Milgram’s study, moderate in Bandura’s, and relatively minor in Loftus and Palmer’s (though still involving deception).

Final Thoughts

Evaluating the research methods shows that while laboratory experiments are powerful tools for establishing cause and effect, their artificial nature can limit real‑world application. Milgram’s and Bandura’s studies benefited from strong control but were criticised for setting‑based and sample‑related limits. Loftus and Palmer’s work was simple and precise but also faced questions about realism.

In all cases, a balance existed between control and ecological validity. The choice of method directly shaped how convincing and useful each set of findings became. A complete psychological picture often needs different methods — such as field studies or longitudinal designs — to complement the benefits and address the limitations seen here.