Chapter 9: Research Methods in Psychology
Psychological research aims to explore and understand human behaviour, thoughts, and emotions through systematic investigation. The methodologies used in this field are broadly categorised into experimental and non-experimental approaches, each offering distinct strengths and limitations. Researchers choose the most appropriate method based on the nature of their research questions, ethical considerations, and practical constraints.
Experimental research is designed to establish cause-and-effect relationships by manipulating an independent variable (IV) and measuring its impact on a dependent variable (DV), while controlling for extraneous factors. Several experimental designs exist, including between-subjects designs, where different groups of participants experience different levels of the IV; within-subjects designs, where the same participants experience all levels of the IV; and matched-groups designs, where participants are matched on specific characteristics to ensure comparable groups. Quasi-experimental designs, which lack either random assignment or strict control over extraneous variables, are also commonly used in situations where traditional experimental methods are impractical.
In contrast, non-experimental methods do not involve manipulating variables. Instead, they focus on measuring and observing variables as they naturally occur to identify relationships or describe phenomena. These methods are particularly valuable when experiments are impractical, unethical, or impossible. Examples include correlational research, which examines the statistical relationships between variables; survey research, which gathers self-reported data through questionnaires or interviews; and qualitative research, which provides an in-depth exploration of human experiences and behaviours using non-numerical data.
Both experimental and non-experimental methods are essential for advancing psychological knowledge. While experimental methods are unparalleled in establishing causality, non-experimental methods excel in identifying patterns, generating hypotheses, and studying variables within natural contexts. The sections ahead will explore these methods in greater detail, highlighting their design, implementation, and interpretation, as well as their respective strengths and limitations. Whether conducted in controlled laboratory settings or through open-ended exploration, these research approaches are fundamental to enhancing our understanding of the human mind and behaviour.
Learning Objectives
By the end of this chapter, you should be able to:
- Understand the role of experiments in establishing causal relationships: Explain how independent and dependent variables are manipulated and measured in psychological experiments to determine cause-and-effect relationships.
- Differentiate between between-subjects and within-subjects designs: Compare the strengths and limitations of between-subjects and within-subjects experimental designs.
- Explain the importance of controlling extraneous variables: Describe how random assignment, standardisation, and counterbalancing help reduce the impact of extraneous variables on experimental outcomes.
- Identify the four types of validity in research: Define internal, external, construct, and statistical validity, and explain their significance in evaluating experimental research.
- Differentiate between true experiments and quasi-experiments: Explain the key differences between true and quasi-experiments and describe common quasi-experimental designs such as pretest-posttest and interrupted time series.
- Understand the use of survey research in psychology: Describe the key features of survey research, including self-report measures, sampling, and the design of effective survey questions.
- Analyse factorial designs and interaction effects: Explain the structure of factorial designs, identify main effects and interactions, and describe how factorial experiments allow researchers to examine complex relationships between multiple independent variables.
- Compare qualitative, quantitative, and mixed-methods research: Identify the strengths and limitations of qualitative, quantitative, and mixed-methods approaches in psychological research.
