Hypothesis and Variables

In psychology a hypothesis is:

• A clear statement
• A prediction
• Testable
• Formulated at the beginning of the research process

Psychologists start with a theory which a general idea about a behaviour and then develop a hypothesis which makes the theory testable.

Experiments compare 2 conditions that are identical in all respects, expect for the factors being investigated.

The experimenter controls the presence, absence or intensity of factors - variables - thought to affect the behaviour being studied.

To effectively study variables they need to be operationalised (made measurable)

IVs and DVs

 

IVs are also known as Independent Variables - these are manipulated by the experimenter.

 

DVs are dependent variables - these are dependent on the IV manipulations. They could be scores, results from tests, observations etc.

 

E.g. Students wearing underpants get better grades than students wearing no underpants. *

IV= underpants

DV= grades

 

Null Hypothesis

*Null hypothesis (add 'not') - There will ('not'-null hyp) be a significant increase (directional - if you change it you can make it non-directional) in the number of words recalled by people aged 18-44 years, when compared to the number of words recalled by people aged 65 and over.

In psychology, there are two types of Hypothesis. It is important to distinguish between them, especially for four coursework:

 

The Experimental/Alternative Hypothesis - makes a prediction about how an experiment will turn out. They should always be specific.

 

Experimental Hypothesis (Alternative):

• Directional (when previous research indicates an outcome) - Specific prediction about which condition will do best (one tailed test)**
• Non-directional - not specific highlights that there will be a difference between 2 conditions (2 tailed test) **

Null Hypothesis

We would use Null hypothesis:

• When there is no previous research or highly contradictory research
• Same statistical tests require non-directional hypothesis

**One-tailed (direction of result is anticipated)
"There will be a significant increase in (scores in condition one), when compared to (scores in condition two)"

OR

"There will be a significant (positive/negative) correlation between (variable one) and (variable two)"

**Two-tailed (direction of result not anticipated)
"There will be a significant (difference/correlation) between (scores in condition one), and (scores in condition two).

For Null hypothesis add 'NOT'

E.g.

• Altering background noise (IV) affects memory skills (DV) - two-tailed
• Rearing a donkey in a darkened environment (IV) retards the development (DV) of it's eyes - one-tailed  

Don't forget! You only use the term 'Experimental Hypothesis' if you are looking at an experiment - if you are looking at some other kind of study (observation, survey, correlation ect) you should use the term 'Alternative Hypothesis'