Getting Hands-On: The Four Practical Investigations
Welcome to the "doing" part of Psychology! While learning theories is great, psychologists actually have to get out there and test their ideas. For your International AS Level (XPS01), you are required to understand four specific practical investigations—one for each topic (A, B, C, and D).
Why is this important? In your exams, you won't just be asked what Milgram did; you might be asked why you chose a specific design for your own investigation or how you dealt with ethical issues. These notes will help you master the "how-to" of your practicals.
Topic A: Social Psychology Practical (Questionnaires)
In Social Psychology, we often want to know how people think or behave in groups. For this investigation, you design a questionnaire to look for a difference between two groups or conditions.
Key Design Decisions:
• Data Types: You must gather both quantitative (numerical) data using closed questions (like ranked scales) and qualitative (descriptive) data using open questions.
• Sampling: You might use opportunity sampling (whoever is available) or volunteer sampling (advertising for people).
• Analysis: For the numbers, you use descriptive statistics (mean, median, mode). For the words, you use thematic analysis to find recurring patterns or "themes" in the answers.
Quick Tip: Thematic Analysis
Think of thematic analysis like highlighting a transcript. If you ask five people why they obey rules and four mention "fear of punishment," then "fear" becomes one of your themes.
Key Takeaway: Topic A focuses on asking people questions and using both numbers and words to understand social behavior.
Topic B: Cognitive Psychology Practical (Laboratory Experiment)
Cognitive psychology is all about the "mental computer"—memory, perception, and thinking. To test memory fairly, we use a laboratory experiment.
Key Design Decisions:
• Experimental Design: You must use a repeated measures design. This means the same participants take part in both conditions of the experiment (e.g., memorizing a list with music and then memorizing a list in silence).
• Variables: You must operationalize your Independent Variable (what you change) and your Dependent Variable (what you measure).
• Controls: Because the same people do both tasks, you must use counterbalancing (half do Task A then B, half do Task B then A) to avoid order effects like boredom or practice.
• Statistical Test: Because it is a test of difference using repeated measures, you use the Wilcoxon signed ranks test.
Common Mistake to Avoid:
Don't forget extraneous variables! In a memory lab experiment, a noisy radiator or a flickering light could ruin your results. You must control these to keep the study objective.
Key Takeaway: Topic B is a high-control lab study where participants act as their own comparison group (repeated measures).
Topic C: Biological Psychology Practical (Correlational Study)
Biological psychology looks for relationships between things like sleep, hormones, or brain structure and behavior. Instead of looking for a "cause," we look for a correlation (a link).
Key Design Decisions:
• Co-variables: In an experiment, we have IVs and DVs. In a correlation, we have co-variables. For example, Co-variable 1: Hours of sleep; Co-variable 2: Stress rating.
• Visualizing Data: You must use a scatter graph. If the dots go up from left to right, it's a positive correlation. If they go down, it's a negative correlation.
• Statistical Test: You use Spearman’s rank correlation coefficient to see if the relationship is strong enough to be significant. The result is a value between \( -1.0 \) and \( +1.0 \).
• The "Cause and Effect" Trap: Remember, a correlation does not prove that one thing caused the other. It just shows they are related!
Key Takeaway: Topic C is about finding the strength and direction of a relationship between two biological or behavioral measures.
Topic D: Learning Theories Practical (Observations)
Learning theories focus on observable behavior. Therefore, this practical involves observational research.
Key Design Decisions:
• Behavioral Categories: You can't just "watch." You need a coding sheet with specific behaviors to look for (e.g., "kicking," "shouting," "smiling").
• Tallying: You use event sampling (counting every time a behavior happens) or time sampling (recording what is happening every 30 seconds).
• Data Types: You gather quantitative data (the number of tallies) and can also record qualitative notes on the nature of the behavior.
• Statistical Test: To see if there is an association between categories (e.g., "Are boys more likely to be aggressive than girls?"), you use the chi-squared test.
Quick Review: Reliability
To make your observation reliable, use two observers. If they both agree on the number of tallies, you have high inter-rater reliability.
Key Takeaway: Topic D is about watching behavior objectively using checklists and tallying how often things happen.
The Golden Rule: Ethics in Practicals
No matter which topic you are investigating, you must follow the British Psychological Society (BPS) Code of Ethics (2009). Even though these are student practicals, you must ensure:
1. Informed Consent: Participants should know what they are getting into.
2. Right to Withdraw: They can leave at any time.
3. Confidentiality: Keep their names out of your report.
4. Protection from Harm: Don't cause physical or mental distress.
5. Animal Research: If you were studying animals (Topic D), you must follow the Scientific Procedures Act (1986) and Home Office Regulations, focusing on the "3 Rs": Replace, Reduce, Refine.
Summary Table for Revision
Topic A: Questionnaire | Difference | Mean/Median/Mode | Thematic Analysis
Topic B: Lab Experiment | Repeated Measures | Wilcoxon Test
Topic C: Correlation | Scatter Graph | Spearman's Rank
Topic D: Observation | Tallying/Categories | Chi-Squared Test
Quick Math Reminder for the Exam:
When using inferential tests like the Wilcoxon, Spearman, or Chi-squared, you compare your observed value (the one you calculated) to the critical value found in a table. Usually, we look for a significance level of \( p \le .05 \). This means there is a 5% or less possibility that our results happened by chance.