Hypotheses

What is a hypothesis? A precise and testable statement A prediction about what the outcome of an experiment will be Usually derived from a theory It is a statement about populations not samples

Different types Directional hypothesis –Also known as one-tailed Non-directional hypothesis –Also known as two-tailed Experimental / alternative hypothesis Null hypothesis

Directional hypothesis States the kind of difference or relationship between two conditions or two groups of participants predicts what way the results will go Also called one-tailed When you look at a one tailed cat with butter on the end of its tail you know which way it is going if it wants to lick it off Example People who do homework without the TV on will produce better work that those who do homework with the TV on

Non-directional hypothesis Predicts that there will be a relationship between two conditions or two groups of participants Also known as ‘two-tailed’ This time the cat has two tails with a lump of butter on the end of each one. So which way is the two tailed cat going to go? Example There will be a difference in HW produced with the TV on and that produced with the TV off

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Null Hypothesis (H 0 ) This is a statement of no relationship between the variables being investigated Any observed differences between conditions will be down to chance alone Example There will be a no difference in HW produced with the TV on and that produced with the TV off

Activity Complete the exercises on hand out

Research Methods Independent & Dependent Variables

Independent Variables The independent variable is the thing the psychologist changes or manipulates when conducting an experiment. This is to try and discover a cause-effect relationship between the IV and the dependent variable.

Example… An example of an independent variable: whether participants in a memory experiment were asked to make a story out of a list of words (to help them memorise the words) or given no instructions on how to memorise the words

Dependent Variables The name given to the variable in experimental research that measures/ observes any change in animal or human behaviours as a result of their exposure to the independent variable.

As a consequence we can discover if the change or manipulation of an independent variable has caused, or had an effect on how we think, feel, or behave; this change being measured as the dependent variable

Example… The dependent variable for a memory experiment could be: The number of words recalled

Test… You must decide which of the following are IVs or DVs… 1.Giving ppts either alcohol or juice 2.Ppts ability to drive safely 3.Whether ppts memorised words at the bottom of the ocean or on the beach 4.The number of anagrams solved in 2 minutes 5.The attention span of a gold fish 6.The time of day

Now you need to have a go… See IV – DV handout

Controlling of variables Sometimes its hard to control our variables Any unwanted variable is known as Extraneous variables –This could be something simple such as light, temp of room etc. We therefore have to identify and try to control!

Confounding variables Confounding variables are other variables that DO change the IV These are variables that we didn’t identify and only after our experiment do we notice!

Demand characteristics This is a very important term! Most participants will try and work out what is going on… try to guess your experiment You may give them clues… …. Which in turn will make them change their behaviour Ultimately the behaviour will not be natural and therefore have an affect on your results… an extraneous variable?