Aims and hypotheses
What are aims in psychological research? The aims of a study are an
overview of what the researcher wants to achieve/ investigate.
The effect of alcohol on memory loss
The relationship between age and stress
Pick a couple of studies from PY2, and state what the aims of these studies were. Come
up with an aim of something that you would like to investigate.
Remember, an aim is not the same as a hypothesis! An aim is a general statement of the researcher’s
intention. It tells us nothing about what he predicts is going to happen.
An aim needs to be changed into a hypothesis
“Investigating the effect of sleep deprivation on self esteem” is too vague to
produce any meaningful result.
What exactly are we testing?
How will we test it?
How do we define and measure sleep and self esteem
What do we think will happen?
Psychologists change these aims into a hypothesis. This is a clear, testable statement that makes a
prediction about what will happen in a piece of research.
Before deciding on a hypothesis, we need to define our variables.
What is an IV?
What is a DV?
On the sheet, read the 7 aims and identify the IV and DV
However, stating the variables is not enough. We need to be able to measure them. This is called
operationalising. This is vital for the research, as if we were unable to measure our variables, how
would we be able to interpret our results?
How could we operationalise “Investigating the effect of sleep deprivation on self esteem”?
On the sheet, operationalise the variables for a few of the studies
The Alternate Hypothesis
A statement that makes a prediction that something will happen in a study is called an “alternate
hypothesis”. A hypothesis should be TESTABLE (it includes the IV and the DV).
The Null Hypothesis
The opposite of the alternate hypothesis is the null hypothesis. Whereas the alternate hypothesis says
that something will happen, the null hypothesis says that nothing will happen.
How do we use hypotheses?
In a study, we need both an alternate and a null hypothesis (the alternate can be either directional or
non-directional). (Delete as appropriate)
If our results support our alternative hypothesis, we accept/reject the alternative hypothesis
and accept/reject the null hypothesis
If our results contradict our alternative hypothesis, we accept/reject the alternative
hypothesis and accept/reject the null hypothesis
Directional Hypothesis (One tailed)
A directional hypothesis predicts that the independent variable will have an effect on
the dependent variable in a specific direction.
This could be as a difference
“People who sleep for more than 7 hours a night score will higher on a test of
self esteem than those who sleep for less than 7 hours a night”
Or as an association/correlation
“There will be a positive correlation between number of hours slept and self
esteem, (the more hours sleep a person gets, the higher their self esteem)”
We are predicting that there will be a difference between the two conditions, and that
that difference will only go in the direction stated by the hypothesis.
Non-directional Hypothesis (Two tailed)
A non directional hypothesis likewise states that changing the IV will have an effect on
the DV, but it doesn’t say in which direction.
“There will be a difference in scores of self esteem between people who use
sleep for more than 7 hours a night and those who sleep less”
Here, it may be that people who sleep more have higher self esteem, or it could be the
opposite; people who sleep more have lower self esteem. Either way, the hypothesis
predicts a difference, but this difference could be in either direction.
A statement that predicts nothing will happen and that altering the IV will have no
effect on the DV.
“The hours of sleep per night will have no effect on the self esteem scores of
This hypothesis states that the IV will have no effect on the DV. This is the opposite of
the alternate hypothesis.
On the handout, have a go at writing directional, non directional and null hypotheses for
the aims given