01. Variables, Hypothesis and Scientific Method

As psychology is a science, it must follow the process of the scientific method as displayed in this image.

All sciences follow this procedure as it allows us to systematically invesitage a possible cause and effect relationship between two variables. Due to the human element of psychology there are a number of other variables (such as individual differences) that may interfere with experimentation. For that reason it is extremely important that experiments are designed with a lot of attention to detail, ensuring that we are isolating our experiment to the relationship between the IV and the DV

VARIABLES

A controlled experiment is an experimental investigation to test the relationship between an independent variable and a dependent variable, whilst controlling all other variables. For example, to test whether talking on a hand-held mobile phone while driving (one variable) causes or influences a change in driver reaction time (another variable), or whether access to a reward (one variable) has an effect on exam performance (another variable).

A variable is something that can change or vary in an experiment. In most cases these changes will be deliberately implemented or measured by the researcher, though there may be circumstances where unwanted factors are causing a change. Variables come in one of a few forms:

INDEPENDENT VARIABLE: The variable that is manipulated in order to measure its effect on the dependent variable is called the independent variable (IV). It is sometimes referred to as the ‘treatment’ or ‘treatment variable’ to which participants may be exposed (or not exposed). The IV is assumed to have a direct effect on the dependent variable. Therefore, in terms of cause and effect, the IV is viewed as the cause of any change that may result in the dependent variable.

DEPENDENT VARIABLE: The variable that the researcher uses to observe and measure the effects of the IV is called the dependent variable (DV). It is the aspect of a participant’s behaviour or experience that is assumed and expected to change as a result of the manipulation of the IV selected by the researcher

In this example we can see that the IV is whether or note the participant watches a violent tv program and the DV is the incidence of aggressive behaviour. The group that is exposed to the IV (the group that watches the violent program) is known as the experimental group. The group that does not watch the violent program is known the control group. A control group exists so we can look at the differences in the change to the DV to establish if the IV had an impact. If we were to see a significant rise in the incidence of aggressive behaviour among those people who watched a violent TV show then we may be able to conclude that the violent tv show was responsible for this change in the DV.

In any psychoilogical experiment there are potentially a range of variablkes other than the IV that may affect the DV. These "extraneous" variables are unwanted and should be controlled and minimised at all times. Throughout this chapter we will learn many ways that we can control extraneous variables ands therefore further isolate the relationship between the IV and DV.

Operationalising Variables

Operationalising the IV and DV involves defining how they will be manipulated or measured in the experiment (or other investigation). This is an important step because many of the behaviours and mental processes psychologists investigate can have different meanings and can therefore be specifically denied, manipulated or measured in more than one way. For example, consider an experiment to investigate whether exercise provides relief from depression. ‘Exercise’, which is the IV, might be operationalised as ‘walking at a particular pace for a specified period of time on an automated treadmill’. ‘Depression’, which is the DV to be measured, might be operationalised as ‘the number of negative words used in writing a creative story’, as it has been found through previous research studies to be related to the severity of depression.

AIM:

The aim is a statement outlining the purpose of the investigation. It can range in length from a single sentence to a short paragraph and should be expressed as clearly and precisely as possible. Some examples of appropriate research aims are:

The aim of this investigation is to compare differences in the amount of sleep obtained by adolescents and very old people.
The aim of this experiment is to assess the effects of practice on learning.
To examine the effects of different types of feedback on performance of a novel task.
To investigate the effectiveness of acronyms in aiding recall.
To identify sex differences in the use of approach and avoidance strategies for coping with stress.

When writing the aim for one of your investigations, consider the following points:

Ensure the aim describes the purpose of your investigation — what you are actually trying to find out from conducting the investigation.
Make the aim as clear and uncomplicated as possible.
Try and limit the aim to a single sentence to help focus your thinking.
It may help to try expressing the aim as a research question to start with.
If you have both a research question and an aim, ensure your aim clearly and closely relates to the research question.
If you have more than one aim, ensure the aims are related.

HYPOTHESIS

A research hypothesis is a clear and testable prediction about how two or more things (called variables) are related. These variables can be events (things that happen) or characteristics (traits or qualities).

For example, a research hypothesis might predict a relationship between:

Talking on a mobile phone while driving (event) and driving performance (event)
Biological sex (characteristic) and oral language skills (characteristic)
Exposure to stress (event) and heart rate (characteristic)

Key Points About a Research Hypothesis:

It describes what the researcher expects to find in their study, based on previous research, theories, or models. That’s why it’s sometimes called an educated guess.
It is created before the investigation starts and gives a clear focus to the research.

Characteristics of a Good Research Hypothesis:

Testable & Measurable – The variables should be things that can be observed and measured. For example, driving performance can be tested in a simulator, but the idea that people "see a bright light when they die" can’t be measured, so it wouldn’t be a good hypothesis.
Can Be Proven Right or Wrong – The hypothesis should be able to be supported or refuted based on collected data.
Describes a Relationship – It should clearly state how two or more variables are connected.
Indicates Direction of Relationship – It should explain how one variable affects another. For example, does talking on the phone while driving make driving performance worse?
Provides a Possible Explanation – It should suggest a reason for the expected results. For example, driving performance might decline due to distraction from phone use.
Based on Prior Knowledge – It should be built on observations, theories, models, or previous research.
Clearly Written – It should be:
- A complete statement, not a question.
- Precise and specific, not vague or general.
- Written as a single sentence.

A well-formed hypothesis helps guide research and ensures the study has a clear purpose and direction.

Importance of Variable Relationship

The link between your independent and dependent variables is the foundation of your hypothesis. This relationship tells you what effect to expect (dependent variable) when you manipulate a condition (independent variable). The hypothesis should make a clear predictive statement based on theoretical reasoning or previous empirical research.

Simple Hypothesis Examples and Their Variables

1. **Effect of Exercise on Mood:**

- **Independent Variable:** Amount of exercise (e.g., none, 30 minutes, or 60 minutes daily).

- **Dependent Variable:** Self-reported mood score.

- **Hypothesis:** Individuals who engage in 60 minutes of exercise daily will report higher mood scores than those who do not exercise.

2. **Social Media Usage and Loneliness:**

- **Independent Variable:** Hours spent on social media per day.

- **Dependent Variable:** Scores on a loneliness scale.

- **Hypothesis:** Teenagers who use social media for more than 3 hours a day will report higher levels of loneliness than those who use it less than 1 hour.

3. **Group Study vs. Solo Study on Test Performance:**

- **Independent Variable:** Study method (group study vs. solo study).

- **Dependent Variable:** Scores on a science test.

- **Hypothesis:** Students who participate in group study sessions will score higher on science tests than students who study alone.

By clearly linking your independent and dependent variables within your hypothesis, you ensure that your research is focused, relevant, and contributes meaningfully to psychological understanding. This approach not only helps in testing the hypothesis but also in interpreting the results in a broader scientific context.

Learning Activity 3.3.1

Questions on Hypothesis Construction

Question 1: Identify the Variables
Given the following hypothesis: "Increasing the amount of time spent studying the night before an exam will increase the scores on the exam."
a. What is the independent variable?
b. What is the dependent variable?

Question 2: True or False and Explanation
"Good hypotheses need not be testable as long as they are based on strong theoretical backgrounds." True or False? Explain your answer.

Question 3: Hypothesis Formulation
You read a study that suggests high school students who eat breakfast perform better in school. Formulate a hypothesis about the relationship between eating a healthy breakfast and academic performance in middle school students.

Question 4: Evaluate the Hypothesis
Consider the following hypothesis: "Watching TV before going to bed causes nightmares."
a. Is this hypothesis testable and falsifiable? Why or why not?
b. How could you improve this hypothesis to better adhere to scientific research standards?

Learning Activity 3.3.1 Answers

Answer to Question 1:
a. Independent Variable: The amount of time spent studying
b. Dependent Variable: Scores on the exam

Answer to Question 2:
False. A good hypothesis must be testable and falsifiable, regardless of its theoretical backing. This ensures that empirical methods can be used to support or refute it, which is a fundamental principle of scientific research.

Answer to Question 3:
A potential hypothesis could be: "Middle school students who eat a healthy breakfast will have higher academic performance, as measured by their grades, compared to those who do not eat breakfast."

Answer to Question 4:
a. The hypothesis as stated is somewhat testable (you could experiment with TV viewing and report nightmare frequency), but it's not clearly falsifiable because it's too broad and lacks specificity. It does not specify what kinds of TV shows or what "watching TV before bed" precisely entails (e.g., immediately before bed, type of content, viewer's sensitivity, etc.).

b. To improve this hypothesis: "Children aged 6-12 who watch horror films on TV immediately before bedtime will report a higher frequency of nightmares than those who watch non-horror genre films."

Page updated

Report abuse