Welcome to Practical Investigations!

In Psychology, we don't just sit around wondering why people behave the way they do—we go out and find the answers! Practical investigations are the heart of the subject. In your OCR AS Level course, you are required to actually conduct and analyse your own research. This guide will walk you through the four main methods you need to master and how to plan them successfully. Don't worry if this seems like a lot at first; research is just like following a recipe, and we’re going to break it down step-by-step.

1. The "Big Four" Research Methods

The syllabus requires you to undertake investigations in four specific areas. Think of these as the four main tools in a psychologist's toolkit.

Method A: The Experiment

This is the only method that can tell us about cause and effect. You change one thing to see if it makes something else happen.
Example: Does drinking coffee (IV) make students type faster (DV)?

  • Laboratory Experiment: Done in a controlled room. Like testing a car in a high-tech factory.
  • Field Experiment: Done in a real-life setting (like a school or street). Like testing a car on a real road.
  • Quasi Experiment: When the researcher can't randomly put people into groups because they are already in them (e.g., comparing boys vs. girls).

Method B: Observation

Here, you simply watch and record behavior without interfering. It’s like being a "fly on the wall."

  • Naturalistic vs. Controlled: Are you watching people in their natural environment or in a lab?
  • Participant vs. Non-participant: Are you joining in the activity or watching from a distance?
  • Overt vs. Covert: Do the people know you are watching them? (Covert means they don't know—it’s "undercover").

Method C: Self-Report

Instead of watching people, you ask them directly what they think or feel. This usually involves Questionnaires or Interviews (Structured, Semi-structured, or Unstructured).

Method D: Correlation

This looks for a relationship between two things. It doesn't prove that one thing causes the other; it just shows they change together.
Example: As the temperature goes up, ice cream sales also go up (Positive Correlation).

Quick Review: Which method is best for finding cause-and-effect? (Answer: The Experiment!)

2. Planning Your Investigation

Before you start, you need a solid plan. A map is useless if you don't know where you’re going!

Aims and Hypotheses

An Aim is a general statement about what you want to study. A Hypothesis is a specific, testable prediction.

  • Null Hypothesis: Predicts that nothing will happen. \(H_0\)
  • Alternative Hypothesis: Predicts that something will happen. \(H_1\)
  • One-tailed (Directional): Predicts exactly which way the results will go (e.g., "People will get faster").
  • Two-tailed (Non-directional): Predicts there will be a change, but doesn't say which way (e.g., "There will be a difference in speed").

How to get your "Participants" (Sampling)

You can't test everyone in the world, so you need a Sample. Think of it like tasting a spoonful of soup to see if the whole pot needs more salt.

  • Opportunity Sampling: Picking whoever is available at the time. (Quick, but might be biased).
  • Random Sampling: Everyone has an equal chance of being picked. (The "Gold Standard" for fairness).
  • Snowball Sampling: You find one person, and they find their friends. (Great for "hidden" groups).
  • Self-selected Sampling: People volunteer themselves after seeing an ad.

Key Takeaway: Your choice of sample affects how well you can generalise (apply) your results to the rest of the target population.

3. Making it "Scientific": Variables and Design

To keep things fair, you must handle your Variables carefully.

Variables

  • Independent Variable (IV): The thing you change or manipulate.
  • Dependent Variable (DV): The thing you measure.
  • Extraneous Variables: "Nuisance" things that might mess up your results (like a loud noise outside). You must control these!

Experimental Designs (The Layout)

  1. Independent Measures: Different people in each group. (No "practice" effect, but you need more people).
  2. Repeated Measures: The same people do both tasks. (Fewer people needed, but they might get bored or better with practice).
  3. Matched Participants: Different people in each group, but you pair them up based on similarities (like age or IQ).

Memory Aid: Think of Independent measures as Individual groups for different people. Think of Repeated measures as Roing (doing) it twice!

4. Ethics: Doing the Right Thing

Psychology is about people, so we must be kind. The British Psychological Society (BPS) has four big rules. Just remember the word RICR (pronounced "richer"):

  • R - Respect: Give informed consent, allow the right to withdraw, and keep data confidential.
  • I - Integrity: Be honest. Avoid deception unless it is absolutely necessary.
  • C - Competence: Only do research you are trained for.
  • R - Responsibility: Protect participants from harm and always debrief them at the end.

What about animals?

If you use animals, follow the 3Rs:

  1. Replacement: Can you use a computer model instead?
  2. Reduction: Use the smallest number of animals possible.
  3. Refinement: Make sure the animals are as comfortable as possible.

5. Handling Your Data

Once you've done your study, you'll have a pile of numbers or words. You need to make sense of them!

Types of Data

  • Quantitative Data: Numbers. (Easy to graph, but lacks detail).
  • Qualitative Data: Words and descriptions. (Rich in detail, but hard to compare).
  • Primary Data: Collected by you for your study.
  • Secondary Data: Collected by someone else (like looking at old records).

Descriptive Statistics

These summarize your data:

  • Mean: The average. \( \text{Mean} = \frac{\sum x}{n} \)
  • Median: The middle number when they are in order.
  • Mode: The most common number.
  • Range: The difference between the highest and lowest scores.

Common Mistake to Avoid: Don't just list your raw data. Your Results section should always use Descriptive Statistics and Graphs (like Bar Charts or Scatter Diagrams) to make the pattern clear.

6. Writing Your Report

Psychologists follow a strict order when writing up their practical investigations. Think of it as a storybook with specific chapters:

  1. Abstract: A tiny 150-word summary of the whole thing.
  2. Introduction: Why did you do the study? (The background).
  3. Method: How did you do it? (Includes Design, Sample, Apparatus, and Procedure).
  4. Results: What did you find? (Graphs and stats).
  5. Discussion: What does it mean? How could you improve it?
  6. References: Where did you get your information? (Use the Harvard System).
  7. Appendices: The "extras" like raw data or copies of questionnaires.

Quick Review: If you want to see exactly how a researcher carried out their study, which section of the report should you look at? (Answer: The Method section!)

Don't worry if this seems tricky at first! The best way to learn research methods is to actually do them. Every mistake you make in your practical is just a great "improvement" point to write about in your discussion section!