Scientific processes

What you'll learn

• What makes psychology “scientific”: empirical evidence, objectivity, falsifiability, and replication.
• How theories lead to hypotheses, data collection, and theory refinement.
• What paradigms and paradigm shifts mean in psychology.
• How scientific investigations are reported and evaluated in AQA Psychology.

Why psychology tries to be scientific

Psychology studies behaviour and mental processes. Because people are complex, psychologists need methods that are more reliable than guesswork, common sense, or personal opinion.

A scientific process is a systematic way of developing explanations, testing them with evidence, and changing them when the evidence does not fit.

In psychology, this might mean testing whether leading questions affect eyewitness memory, as in Loftus & Palmer (1974), or whether people obey authority figures, as in Milgram (1963). These studies were influential, but they also remind us that psychological science must consider ethics such as consent, deception, right to withdraw, protection from harm, confidentiality, and debriefing.

The scientific process is best understood as a cycle: theories generate hypotheses, hypotheses are tested, findings are reported, and other researchers try to replicate or challenge them.

Empirical method: evidence first

In psychology, empirical evidence could include reaction times, questionnaire scores, brain scans, behaviour counts, interview transcripts, or test scores.

For example, instead of simply saying “stress affects memory”, a psychologist might measure participants’ recall scores after exposing them to different stress conditions. The key point is that the claim is tested against evidence.

Objectivity: reducing personal bias

Psychologists try to increase objectivity by using:

• Standardised procedures: every participant experiences the same instructions and conditions.
• Operationalisation: variables are clearly defined so they can be measured.
• Controls: extraneous variables are managed so they do not distort the results.
• Peer review: other experts check the quality of the research before publication.

Objectivity is especially important because researchers can unintentionally influence participants. In Zimbardo’s Stanford prison study (1973), for example, Zimbardo acted as both researcher and prison superintendent, which raises concerns about investigator effects and protection from harm. Modern ethical standards would require clearer safeguards, withdrawal rights, and monitoring of distress.

Falsifiability: a claim must be testable

This idea is strongly associated with philosopher Karl Popper. For Popper, science does not work by proving theories true forever. Instead, scientists make bold predictions and try to test whether those predictions fail.

A claim like “people behave aggressively because of invisible forces that can never be measured” is difficult to treat scientifically because no evidence could disprove it. A better scientific claim would be: “Participants exposed to violent media will show higher aggression scores on a standardised task than participants exposed to non-violent media.”

Hypothesis testing and theory construction

Psychologists often use:

• An alternative hypothesis ($H_1$): predicts that there will be a relationship or difference.
• A null hypothesis ($H_0$): predicts that there will be no relationship or difference, and any pattern is due to chance.

If results are statistically significant, often using the default level of $p<0.05$, researchers usually reject the null hypothesis. If not, they retain or fail to reject it.

Theory construction is not a one-off event. Evidence builds gradually. If many studies support a theory, confidence increases. If findings conflict with the theory, psychologists may revise it, limit its claims, or reject it.

For example, early memory theories were refined as new evidence emerged. The working memory model proposed by Baddeley and Hitch, later developed by Baddeley (1986), challenged the idea of short-term memory as one simple store by suggesting separate components for different types of information.

Replicability: can others get similar results?

Replication matters because one study can be affected by chance, sampling bias, poor controls, or researcher expectations. If a finding is replicated across different researchers, samples, and settings, it becomes more trustworthy.

There are two useful types:

• Direct replication: repeats the original method as closely as possible.
• Conceptual replication: tests the same underlying idea using a different method, task, or sample.

In psychology, replication can be difficult because human behaviour is influenced by culture, time, setting, and individual differences. For instance, obedience findings from Milgram (1963) may not generalise neatly across all cultures or historical periods. The original also involved major ethical issues, especially deception, stress, and questions about the right to withdraw.

Paradigms and paradigm shifts

The idea is linked to Thomas Kuhn, who argued that sciences often work within a dominant paradigm until enough problems, or anomalies, build up. A major change in thinking is called a paradigm shift.

In psychology, examples include:

• The move from behaviourism to the cognitive approach, as psychologists began to study internal mental processes scientifically.
• The growth of the biological approach, using methods such as brain scanning and genetic research.
• Challenges to psychiatric diagnosis, such as Rosenhan (1973), which questioned whether mental health professionals could reliably distinguish sanity from insanity. Rosenhan’s study also raised ethical issues because hospital staff were deceived and could not give informed consent.

Psychology is often described as multi-paradigmatic because different approaches exist side by side: biological, cognitive, behavioural, psychodynamic, and humanistic.

Reporting psychological investigations

Scientific findings need to be written up clearly so other researchers can evaluate and replicate the study.

AO3: evaluating scientific processes in psychology

Strengths

Scientific processes make psychology more rigorous. Objectivity, operationalisation, and standardisation reduce bias and make findings easier to check. Replication helps separate reliable findings from one-off results. Empirical evidence also supports real-world applications, such as improving eyewitness interview techniques after research like Loftus & Palmer (1974).

Scientific reporting also increases transparency. If researchers describe their method clearly, others can identify flaws, repeat the study, or test the theory in new contexts.

Limitations

Human behaviour is complex, so scientific control can sometimes reduce realism. A laboratory study may be objective and replicable but lack ecological validity, meaning it may not reflect real-life behaviour.

Some psychological topics are also hard to falsify. For example, broad claims about unconscious motivation can be difficult to test directly. Ethical rules also limit what psychologists can do: researchers cannot deliberately cause serious harm just to test a theory.

Finally, science is carried out by humans. Researchers may be influenced by funding, cultural assumptions, publication bias, or dominant paradigms. Peer review helps, but it is not perfect.