Theory Construction & Hypothesis Testing (AQA A-Level Psychology): Revision Notes
Theory Construction & Hypothesis Testing
Theory construction
Theory construction refers to the process through which hypotheses are developed and tested under controlled scientific conditions to create explanations for observed phenomena. This process forms the foundation of scientific enquiry and allows researchers to move beyond simple observations towards comprehensive understanding.
According to Karl Popper, theories represent the first stage of the scientific process. Rather than relying on chance observations, science depends on carefully arranged, unbiased observations that yield information about the world. This information is then formulated into theories that attempt to explain phenomena through testable predictions.
Popper's contribution to scientific methodology emphasises that science should be based on systematic, controlled observations rather than random chance discoveries. This approach ensures that scientific theories are built on reliable foundations.
The scientific method cycle
The scientific method operates as a continuous cycle with two distinct phases:
1. Inductive phase - This stage involves making observations that provide information used to formulate theories as explanations for phenomena. Researchers gather data from the world around them and identify patterns or relationships that require explanation.
2. Deductive phase - During this stage, predictions are made from existing theories in the form of testable hypotheses. These hypotheses are then experimentally tested, producing data that can be statistically analysed to determine whether the theory should be refuted, falsified, or adjusted.
This cyclical process demonstrates verisimilitude - the idea that scientific theories progressively gain closer approximation to the truth through repeated testing and refinement.
Popper argued that while theories can be easily disproved through contradictory evidence, they can never be proven with absolute certainty. This fundamental principle means that all scientific theories remain tentative and subject to revision based on new evidence.
Hypothesis testing and empirical methods
Hypothesis testing involves the systematic assessment of testable predictions under scientifically controlled conditions. The most robust empirical research method in psychology is the laboratory experiment, which allows researchers to establish causality through controlled manipulation of variables.
Other research methods, whilst having reduced capability to determine causality, can still follow scientific principles. Field experiments and natural experiments, though less controlled, can provide valuable insights. Even non-experimental methods can achieve objectivity through techniques like naturalistic observation, where researchers employ inter-observer reliability to ensure unbiased data collection.
Psychology faces unique challenges as a 'soft science' compared to 'hard sciences' like physics and chemistry. The subjective nature of human behaviour means psychological research cannot always achieve the same level of rigorous control, though scientific principles still apply.
Paradigm shifts
Thomas Kuhn challenged Popper's view of scientific progress, arguing that science advances through revolutionary paradigm shifts rather than steady, cumulative progress. A paradigm represents a shared set of assumptions about a discipline's subject matter and appropriate research methods.
Kuhn observed that scientists often exhibit confirmation bias, seeking evidence that supports their existing hypotheses rather than attempting to refute them. This leads to scientific journals publishing research that confirms established paradigms, focusing on confirmatory rather than contradictory evidence.
Kuhn argued that scientific advancement occurs when the accepted paradigm is replaced by a new one, often emerging from minority positions.
Historical Example: Einstein's Revolutionary Theories
Einstein's theories about the nature of the universe eventually replaced earlier paradigms in physics. His work on relativity challenged the established Newtonian worldview and fundamentally changed how we understand space, time, and gravity. This represents a classic paradigm shift where revolutionary ideas eventually became the new accepted framework.
Psychology itself contains multiple paradigms, including behaviourism and evolutionary psychology, each offering different approaches to understanding human behaviour.
Reporting psychological investigations
Effective scientific communication requires standardised reporting conventions. Progress in science depends on researchers accurately describing their methods and findings, allowing others to replicate and verify results.
Scientific reports typically follow a conventional structure with specific sections:
Abstract - A concise summary of the entire study, usually consisting of two sentences covering theoretical background, aims, hypotheses, methodology, results, conclusions, and future research suggestions.
Introduction - This section explains why the study was conducted, providing theoretical background and previous research. It uses a 'funnel' technique, starting with broad theoretical perspectives before narrowing to specific study aims and hypotheses.
Method/Procedure - Details the design decisions and procedures used in the study, providing sufficient information for replication.
Results/Findings - Presents the study's findings through data analysis.
Discussion - Analyses and evaluates the findings, considering their implications and limitations.
The report must clearly communicate what was done, why it was done, what was found, and what the findings mean. Hypotheses should be stated precisely, including directional predictions (one-tailed or two-tailed) and significance levels (typically p < 0.05).
Summary
Key Points to Remember:
- Theory construction involves a cyclical process of observation, theory formation, hypothesis testing, and theory refinement
- The scientific method operates through inductive phases (observation to theory) and deductive phases (theory to testable predictions)
- Paradigm shifts represent revolutionary changes in scientific thinking, challenging Popper's view of steady scientific progress
- Laboratory experiments provide the strongest evidence for causality in psychology, though other methods can still follow scientific principles
- Scientific reports must follow conventional structures to enable effective communication and replication of research