Welcome to the Psychologist's Toolbox!
Ever wondered how psychologists actually find things out? They don't just guess; they use specific research methods. Think of these methods as a "toolbox." Just as a plumber needs different tools for different jobs, a psychologist chooses the best method based on what they want to discover. In this chapter, we will explore the six main tools you need for your AS Level exam.
1. Experiments
The experiment is the "gold standard" for finding out cause and effect. It’s the only method where we change one thing to see if it causes a change in something else.
Types of Experiments
Laboratory Experiments: These take place in an artificial, controlled environment (like a university lab).
Strength: Very high control over "extra" variables, making them easy to replicate.
Weakness: They can feel "fake," so participants might not behave naturally (low ecological validity).
Field Experiments: These happen in a real-world setting (like a school or a subway station), but the researcher still manipulates a variable.
Strength: Behavior is more natural.
Weakness: It is much harder to control "extra" variables that might mess up the results.
Experimental Designs (How we group participants)
Don't worry if these seem tricky at first! Here is a simple breakdown:
Independent Measures: Different participants take part in each condition. (e.g., Group A does the test with music, Group B does it in silence).
Risk: Participant variables (maybe Group A is just naturally smarter?).
Repeated Measures: The same participants do every condition.
Risk: Order effects. Participants might get better because they practiced (practice effect) or worse because they got tired (fatigue effect).
Matched Pairs: We pair up participants who are similar (e.g., same age or IQ), then put one in Group A and the other in Group B.
Trick: Think of this as trying to create "clones" to make the groups fair!
Quick Review: To stop order effects in repeated measures, psychologists use counterbalancing (half do Condition 1 first, half do Condition 2 first). To make groups fair in independent measures, we use random allocation.
2. Self-Reports
This is simply asking people what they think, feel, or do. There are two main types:
Questionnaires
These can be on paper or online.
Closed questions: Provide fixed options (e.g., "Yes/No" or a scale of 1–10). These give quantitative data (numbers).
Open questions: Let participants write whatever they want. These give qualitative data (detailed descriptions).
Interviews
Structured: Every participant is asked the same questions in the same order.
Unstructured: More like a conversation; questions change based on the answers given.
Semi-structured: A mix of both—some set questions, but room to explore.
Key Takeaway: Self-reports are great for seeing inside someone's head, but people might lie to look better (this is called social desirability bias).
3. Case Studies
A case study is a detailed, in-depth investigation of just one person or a very small group.
Example: Studying a person with a unique brain injury.
Strength: Provides incredibly rich, detailed data that you couldn't get any other way.
Weakness: Because the person is so unique, we cannot easily generalize the findings to everyone else.
4. Observations
This is the "fly on the wall" method where researchers watch and record behavior. Observations are usually categorized in pairs:
Overt vs. Covert: Overt means participants know they are being watched; Covert means they are being watched in secret.
Participant vs. Non-participant: Does the researcher join in with the group (Participant) or stay on the sidelines (Non-participant)?
Structured vs. Unstructured: Does the researcher use a checklist of behaviors (Structured) or just write down everything they see (Unstructured)?
Naturalistic vs. Controlled: Is it in the "wild" (Naturalistic) or in a set-up environment like a lab (Controlled)?
5. Correlations
A correlation looks at the relationship between two "co-variables." For example, as the temperature goes up, does ice cream sales go up too?
Important Rule: Correlations cannot prove that one thing caused the other. They only show that they are linked.
Example: Just because tall people might have higher salaries doesn't mean being tall causes money to appear in your bank account!
6. Longitudinal Studies
These are studies that follow the same participants over a long period of time (weeks, months, or even years).
Strength: You can see how people change over time.
Weakness: They take a long time, and participants often drop out (this is called attrition).
Data Analysis: The Basics
In Psychology (9990), you need to understand how to describe the data you collect. For more on how to evaluate this data, see the chapter on Validity, reliability and data analysis.
Measures of Central Tendency
Psychologists use these to find the "average" result:
Mode: The most frequent score.
Median: The middle score in a list ordered from lowest to highest.
Mean: The mathematical average (add them all up and divide by the number of scores).
Measures of Spread
These show how much the scores vary:
Range: The difference between the highest and lowest score.
\( \text{Range} = \text{Highest Value} - \text{Lowest Value} \)
Standard Deviation: A more complex measure that shows how much scores differ from the mean. You don't need to calculate this, just understand that a small standard deviation means the scores are all very close to the average.
Visualizing Data
You should be able to recognize and draw:
Bar Charts: Used for separate categories.
Histograms: Used for continuous data.
Scatter Graphs: Used to show the relationship in correlations.
Final Planning Tip: For Paper 2, you will be asked to plan a study. Remember that each method has "must-have" features. For example, if you plan an experiment, you must identify your Independent Variable (IV) and Dependent Variable (DV). If you plan a correlation, you need two co-variables!