Defining Psychological Science: The Experimental Method

Lily Scott

7 min read

Next Topic - Selecting a Research Method

Listen to this study note

Study Guide Overview

This AP Psychology study guide covers research methods, including basic vs. applied research, the scientific method (theory, hypothesis, and operational definitions), and variables (independent, dependent, confounding, and control). It also discusses the Hawthorne effect, establishing cause and effect through random assignment, sampling bias and experimenter bias, and common sense biases (hindsight bias, overconfidence, and perceiving order in random events).

#AP Psychology Study Guide: Research Methods 🚀

Hey! Let's get you prepped for the AP Psych exam. This guide will break down research methods in a way that's easy to remember and super helpful for test day. Let's dive in!

#Types of Research

Understanding the difference between basic and applied research is key. Think of it like this:

Basic Research: 🧐 Curiosity-driven, expanding knowledge. Like figuring out how caffeine affects the brain. No immediate practical goal.

Key Concept

Focuses on foundational knowledge rather than solving specific problems.

Applied Research: 🛠️ Problem-solving, practical use. Like finding a cure for OCD. Directly aims to address real-world issues.

Memory Aid

Basic = Building knowledge, Applied = Action-oriented.

#The Scientific Method

It's not just a list of steps; it's how we make sure our findings are solid:

Theory: 🤔 An explanation for observed behavior. This is your starting point.
Hypothesis: 🧪 A testable prediction based on your theory. It's your educated guess.
Operational Definition: 📝 This is crucial. It's how you define your variables so that anyone can replicate your study. Think of it as a recipe for your experiment. For example, instead of saying “intelligence,” you'd say “scores on an IQ test.”

Exam Tip

Pay close attention to how variables are defined in the study descriptions on the exam. This is where many students lose points!

#Types of Variables

Variables are the bread and butter of experiments. Let's break them down:

Independent Variable (IV): 🎛️ The variable you change. It's the cause. Example: the amount of sleep.
Dependent Variable (DV): 📈 The variable that's affected by the IV. It's the effect. Example: exam performance.

Memory Aid

IV = I change it, DV = Depends on the IV.

Confounding Variable: 🚧 An outside factor that messes with your results. For example, the weather affecting ice cream sales and crime rates.

Quick Fact

Confounding variables can lead to spurious correlations, so it's important to control them.

Control Variable: ⚙️ The things you keep the same to ensure a fair test. Example: the same test, sleeping environment, and type of bed for all participants.

Common Mistake

Don't confuse control variables with control groups! Control variables are kept constant across all groups, while a control group is a group that does not receive the treatment.

#The Hawthorne Effect

Remember the Hawthorne Effect? 👁️ People act differently when they know they're being watched. This can mess up naturalistic observations. This is a type of confounding variable.

Image Courtesy of Kiana Matthews.

#Cause and Effect

Experiments are the ONLY way to prove cause and effect! 💡
Random Assignment: ⚖️ Participants have an equal chance of being in any group, making the groups similar at the start. This is crucial for demonstrating cause and effect.

Memory Aid

Random Assignment = Randomly assigning participants to different experimental groups. Random Sampling = Randomly selecting participants from the overall population.

#Types of Bias

Sampling Bias: 📉 When your sample isn't representative of the population. This can skew your results.
Experimenter Bias: 🧑‍🔬 When the researcher unintentionally influences the results.

Exam Tip

Double-blind procedures are a great way to minimize bias. Neither the participants nor the researchers know who is in which group.

#Common Sense?

Why can't we rely on common sense? Because of these sneaky biases:

Hindsight Bias: ⏪ “I knew it all along!” Thinking you predicted an event after it happened.
Overconfidence: 😤 We think we know more than we do, which can lead to errors.
Perceiving Order in Random Events: 🎲 We try to find patterns in randomness, even when they don't exist. Like thinking a coin flip is due for a heads after a bunch of tails.

These biases are frequently tested in both multiple-choice and free-response questions. Make sure you can define and identify examples of each.

#Final Exam Focus

Okay, here's the lowdown on what to really focus on:

High-Priority Topics: Types of research, variables, cause and effect, and biases.
Common Question Types: Identifying variables in scenarios, experimental design flaws, and ethical considerations.
Time Management: Don't spend too long on any one question. If you're stuck, move on and come back later.
Common Pitfalls: Confusing random assignment with random sampling, not understanding operational definitions, and overlooking confounding variables.

#Practice Questions

Practice Question

Multiple Choice Questions

A researcher is conducting a study on the effects of a new medication on anxiety levels. Participants are randomly assigned to either the medication group or a placebo group. What is the independent variable in this study? (A) Anxiety levels (B) The new medication (C) The placebo (D) Random assignment
Which of the following best describes a double-blind procedure? (A) Participants are unaware of whether they are in the control or experimental group, but the researcher knows. (B) Neither the participants nor the researcher knows who is in the control or experimental group. (C) The researcher is unaware of the hypothesis being tested. (D) Both the participants and the researcher know who is in the control or experimental group.

Free Response Question

Dr. Ramirez is conducting a study to investigate the impact of social media use on sleep quality among teenagers. She recruits 100 participants and randomly assigns them to one of two groups: a group that limits social media use to 30 minutes per day and a group that uses social media without any restrictions. After one month, she measures sleep quality using a standardized sleep questionnaire.

(a) Identify the independent and dependent variables in this study. (2 points) (b) Explain how random assignment is used in this study, and why it is important. (2 points) (c) Describe one potential confounding variable that could affect the results of this study. (1 point) (d) Explain how Dr. Ramirez could use an operational definition to measure sleep quality. (1 point) (e) Explain how experimenter bias could affect the results of this study, and how Dr. Ramirez could minimize this bias. (2 points)

Scoring Breakdown

(a) (2 points) * 1 point for correctly identifying the independent variable (social media use). * 1 point for correctly identifying the dependent variable (sleep quality).

(b) (2 points) * 1 point for explaining that random assignment means participants are assigned to groups randomly, with an equal chance of being assigned to either group. * 1 point for explaining that random assignment helps to minimize pre-existing differences between groups, allowing for cause-and-effect conclusions.

(c) (1 point) * 1 point for identifying a plausible confounding variable, such as: stress levels, diet, or pre-existing sleep disorders.

(d) (1 point) * 1 point for explaining that an operational definition is a specific way to measure sleep quality, such as scores on a standardized sleep questionnaire.

(e) (2 points) * 1 point for explaining that experimenter bias could occur if Dr. Ramirez unintentionally influences the results, such as by giving subtle cues to participants in the limited social media group. * 1 point for explaining that Dr. Ramirez could minimize bias by using a double-blind procedure, where neither she nor the participants know which group they are in.

You've got this! Keep reviewing, stay calm, and you'll do great on the exam! 🌟