Experimental Methods Used In Psychological Research
Experimental Methods In Psychology
In the early days, psychology was primarily investigated using a method known as rationalism.
This approach simply involved thinking about something, and then coming up with an explanation as to why it may be that way.
However whilst rationalism may be a useful approach for subjects such as philosophy, in psychology, rationalism can often lead to contradictory ideas.
One such example can be found with John Locke, who believed that at birth the mind was a blank slate. Yet later using same approach, Immanuel Kant concluded that there are some inborn ideas at birth.
This is one of the problems of using rationalism in psychology, as it can lead to two different people coming up with two different ideas.
To produce more concrete ideas, another approach was called for and it came in the form of empiricism.
Empiricism
Empiricism involves gathering information by using the senses, (e.g. hearing, touch, sight, taste and smell) and marks the beginnings of the modern day research methods we use in psychology today.
No longer were psychologists confined to the ideas created by the rationalistic approach, but they could now prove or disprove those ideas with real evidence.
This is how William James believed psychology should be, as he argued that psychology should be treated like a science and therefore investigated in a scientific manner.
The Scientific Method
The scientific method represents the way psychological data is researched and collected today, and is something which evolved from the early methods of rationalism and empiricism that were previously described.
The scientific method aims to gather information in a scientific way, so that it is both accurate and reliable. There are three main steps that must be followed when using this method.
1 – Form A Hypothesis
The first step is to make an educated guess as to why something is the way it is, or in other words, form a hypothesis.
For example, a teacher reads an article about how omega 3 supplements can increase concentration, so they form a hypothesis that omega 3 supplements will have an effect on student test scores.
2 – Gather Data
After forming a hypothesis, the next step is to gather data so that we can test it.
For example, the teacher may split the class into two, giving one half omega 3 supplements and the other half nothing.
3 – Accept Or Reject The Hypothesis
From the data we have collected, we can then determine whether our hypothesis was correct or incorrect.
So if the teacher found that the children who received the omega 3 supplements had higher test scores than those who received no supplements, they can accept their hypothesis that omega 3 affects test scores.
Should however no difference be found between the two groups, the teacher would then reject their hypothesis as the supplements produced no significant difference between the two test scores.
Inaccurate Information
Whilst the scientific method attempts to obtain accurate and reliable information, sometimes it is possible that the information collected was wrong. This is known as a decision error, of which there are two types.
Type I Error
A type I error occurs when a hypothesis has been accepted when it should have been rejected.
A famous example of a type I error occurred when the astronomer Percival Lowell concluded that there were canals on Mars, when later research showed this was not the case.
He made a type I error, because what his evidence told him was correct was actually incorrect.
Type II Error
A type II error occurs when a hypothesis is rejected when it should have been accepted.
For example, before the research done by Louis Pasteur, many doctors rejected the idea that invisible germs cause disease and so saw no point in washing their hands when operating on patients.
They made a type II error, because they rejected something which was correct.
Now that we have looked at how modern day psychologists gather their information, lets look at some of the research methods they can use.
Naturalistic Observation
Naturalistic observation involves studying behaviour in its natural setting, without any influence from the researcher.
This method can be used to study both animals and humans, and works best when the research subjects do not know they are being observed.
This is because people and animals tend to act differently when they know someone is watching them.
If it is not possible for the researcher to hide their presence, they may spend some time with the people or animals they are studying before they begin to record their behaviour.
This allows the researcher to become accepted by the individual or group, so that they will act more naturally and better data can be collected.
Note : Naturalistic observation tends to be most commonly used when observing animal behaviour.
The Clinical Method
The clinical method involves treating people with various disorders, and then using that information for research.
For example, a therapist may have been treating their patient for a number of years, and later decides that because this was an interesting or unique case, they will write about it and maybe even publish it in a scientific journal.
A good example of the clinical method can be found with Sigmund Freud, who from his time spent with patients, came up with many new ideas as to how and why people get sick or have emotional problems in their life.
The Case Study Method
A case study studies one person over a prolonged period of time. Sometimes this might be for a few months, whilst other times it might be a whole lifetime.
Although case studies take a long time to complete, the information they provide is extremely valuable because they allow us to see the long term effects something may have.
One such example can be found with adults were followed up 40 years after an experiment they had done when they were children.
In brief, what the case study found was that the children who were able to delay gratification became much more successful as adults than the children who were unable to delay gratification.
Case studies are also common in medical research, where people are monitored over a period of time so that side effects to drugs can be identified.
The Survey Method
In order understand the behaviour of a large group of people, it is necessary to take a sample of that group which is considered to be representative of the whole.
This sample should be taken at random, so that it incorporates as many different types of people whilst also allowing for chance to operate.
The people within this sample can then be surveyed using methods such as questionnaires or interviews to obtain the relevant data.
One famous example of such a survey was performed by the researcher Alfred Kinsey, who surveyed both males and females about their sexual behaviour.
A film about this was released a few years ago called “Kinsey”, which starred Liam Neeson as Alfred Kinsey.
One drawback however of using the survey method is that because you are only sampling a small subset of a population, you may get biased results if your sample group is not truly representative of the whole.
The Testing Method
As the name suggests, the testing methods uses various tests such as intelligence or personality tests to investigate behaviour.
An example everyone should be able to relate to is the IQ test, which is designed to measure your average level of intelligence.
Some researchers believe that the higher your IQ score is, the more likely you are to have good health and a high income.
However in order for a test to be considered accurate, it needs to be both valid and reliable.
Valid Test
A valid test will test what it is suppose to test. For example, an intelligence test should test your intelligence and not test your personality.
If a test tests something it is not suppose to, it is then considered to be invalid.
Reliable Test
A reliable test is one that produces the same (or very similar) results when it is repeated.
For example, if I get 80% on an intelligence test, and tomorrow when I repeat that test I get 82%, that test could be considered as reliable.
The Correlation Method
Correlation simply means a relationship between two things (variables), and the correlation method is used to determine this by seeing how different things affect each other. The results of which, are usually being displayed on a graph as X and Y.
If one variable can be used to predict the scores of the second variable, they are said to be “covary”, or exhibit “covariance”, which means they vary together.
For example, if X is the size of my left hand and Y is the size of my right hand, I can predict the size of Y by looking at the size of X and vice versa.
However it is important to realise that just because both variables seem to predict each other, it doesn’t necessarily mean that they cause those effects to occur (causation).
Using the same example given above, this would mean the size of my left hand does not cause the size of my right hand. The reason they covary (vary together) is due to something else, genetics.
Types Of Correlations
There are two main types of correlations:
Positive Correlation : This occurs when increasing one variable causes another variable to increase.
e.g. the more time I spend practicing tennis the better a player I become.
or, Increase in X = Increase in Y
Negative Correlation : This occurs when increasing one variable causes the other to decrease.
e.g. the more time I spend watching TV, the worse a tennis player I become.
Or, Increase in X = Decrease in Y
Correlation Coefficient
In order to determine how closely two things are correlated, we use a correlation coefficient which ranges from -1.00 (perfect negative correlation) to +1.00 (perfect positive correlation).
+.77 would be a strong positive correlation, -.33 would be a strong negative correlation.
Determining the correlation between two variables can also be used to determine how valid and reliable a test is.
For example, if an intelligence test has a high positive correlation with grades, then we can say that the test is valid.
If a test is repeated on two separate days and there is a strong positive correlation between the test results, then we can say that the test is reliable.
The Experimental Method
The experimental method allows a researcher to accurately test their hypothesis by giving them control over the variables involved, allowing them to identify why something may be happening (causes) and accurately measure behaviour by using scientific methods.
Generally speaking, there are four factors to take into consideration when using the experimental method.
1 – The Control Group
The control group is used to represent a group that has not been interfered with in any way.
This group shall then be compared to other groups, to see the effects an intervention may have had.
2 – The Experimental Group
This group is who you experiment on, and see how what you do changes their behaviour.
3 – Independent Variable
An independent variable is something which you think will affect another variable.
For example, putting a puppy in a room full of people will cause them to feel happy (change their mood).
4 – Dependent Variable
A dependent variable measures the resulting effect of another variable.
For example, happiness (dependent variable) was a result of bringing the puppy (independent variable) into the room.
The independent variable causes the effect, and the dependent variable measures that effect.
Putting It All Together
If we put all this information together using the example I gave previously about omega 3 and test scores, you may be able to gain a better understanding of the experimental method in action.
Hypothesis - Omega 3 supplements will have an effect on test results.
The first thing we need to do is create two groups, a control (students who will receive no omega 3 supplements) and an experimental group (students who will receive omega 3).
In order for these groups to be fair, we need to divide them by random. This could involve each student writing their name down on paper and being randomly drawn.
This randomisation process will help to cancel out individual differences between the students, which may have given inaccurate or biased results.
The independent variable we are testing is omega 3, because we predict that it will have an effect on test scores. This will be given to the experimental group at a predetermined dose.
The dependent variable is the test score, because we are seeing how students are affected by the omega 3.
If we find that after the experiment omega 3 supplementation results in higher test scores in the experimental group (a positive correlation) we can perform a statistical analysis to see if the result are due to chance.
If they are not, we can then conclude with some degree of certainty that omega 3 supplementation results in better grades.
Note : Omega 3 would have to be given over an extended period of time before the test is taken. Also it is possible for more than one independent variable to be tested for.
Summary Of Experimental Methods In Psychology
• Psychology was first investigated by using a method known as rationalism, which involved thinking about why something may be a certain way.
• Later a method known as empiricism was used, which involved gathering information via the senses.
• Modern day psychology uses the scientific method, which attempts to gather accurate and reliable information in a scientific manner.
• The three main steps in the scientific method are to form a hypothesis, gather data and then accept or reject the hypothesis based on the data collected.
• Although the scientific method is an improvement upon early psychological research methods, it can still result in incorrect information being obtained.
• A type I error occurs when a hypothesis is accepted when it should have been rejected.
• A type II error occurs when a hypothesis is rejected when it should have been accepted.
• Naturalistic observation involves studying people or animals in their natural environment, ideally without them knowing you are there.
• The clinical method bases it research on studies done with people who are suffering from mental or behavioural problems.
• The case study method follows a person over a long period of time.
• The survey method selects a small group which is representative of a larger group. This larger group is usually called a population, which is classified as “a well defined group”.
• The testing method uses various tests such as personality or intelligence tests to investigate human behaviour.
• The correlation method determines if there is a relationship between two variables, and what that relationship is.
• A positive correlation occurs when increasing one variable causes another variable to increase.
• A negative correlation occurs when increasing one variable causes another variable to decrease.
• The correlation coefficient is used to measure the degree of correlation between two variables.
• The experimental method allows things to be tested in a controlled manner, and involves the use of:
• A control group, which receives no interference from the researchers.
• An experimental group, which is experimented on.
• An independent variable, which is used to cause an effect.
• A dependent variable, which is used to monitor the resulting effect of the independent variable.
