Aims & Hypotheses (AQA AS Psychology)

Aims

• The aim of a study takes the form of a general statement covering the topic/theory/concept that will be investigated

• The aim identifies the purpose of the research

  • It is a straightforward expression of what the researcher will attempt to find out by conducting an investigation

• The aim outlines what is being studied and what the study is trying to achieve e.g.

  • 'to investigate the effect of caffeine on memory'

  • 'to investigate the extent to which social facilitation affects sporting performance'

  • 'to investigate deindividuation in prisoners'

Hypotheses

• A hypothesis is a testable statement written as a prediction of what the researcher expects to find as a result of their experiment

• Where the aim of a study is expressed in general terms and outlines the focus of the study; hypotheses must be precise and unambiguous

• There are two types of hypothesis:

  • The null hypothesis (NH)

  • The alternative hypothesis (AH)

Alternative hypothesis

• The alternative hypothesis (AH) should include the independent variable (IV) and the dependent variable (DV)

• Both the IV and the DV in the AH should be operationalised which involves specifics on how each variable is to be manipulated (IV) and measured (DV) e.g.

Operationalising the IV

• Take the example of a memory test performed before and after drinking a caffeinated drink

  • Participants in condition 1 drink 200ml of a caffeinated drink before a memory test; participants in condition 2 drink 200ml of water before a memory test

  • The IV is broken down into two separate conditions, (200ml of caffeine or 200ml of water), each of which is clear from the wording provided

Operationalising the DV

• Keeping with the above example

  • The number of correctly recalled items from a list of 15 words

  • The DV provides the number of total possible correct answers (15) and identifies how participant performance is to be measured (number of correctly recalled items)

Types of alternative hypothesis

• There are two different types of AH

  • Directional (one-tailed)

  • Non-directional (two-tailed)

• A directional hypothesis predicts the direction of the difference in conditions i.e. it state that one condition will out-perform the other

• A directional hypothesis for the above study on caffeine's effect on memory could be written as follows:

  • Participants who drink 200ml of caffeine before taking a memory test will correctly recall more items out of 15 than participants who drink 200ml before taking the same memory test

• A non-directional hypothesis does not predict the direction of the difference in conditions i.e. it simply predicts that a difference will be shown

• A non-directional hypothesis for the above study on caffeine's effect on memory could be written as follows:

  • There will be a difference in the number of correctly recalled items out of 15 depending on whether participants have drunk 200ml of caffeine or 200ml of water before taking a memory test

• The AH predicts the effect of the IV on the DV i.e. it is the hypothesis of ‘difference’ (between conditions)

Null hypothesis

• All published psychological research must include the null hypothesis (NH); this is what all research starts with

• The NH begins with the idea that the IV will not affect the DV

• This is because until the experiment has been conducted and the results are analysed it is impossible to state anything else

• Using the same above example:

  • A researcher thinks that drinking caffeine before taking a memory test will result in a higher score than drinking water before taking a memory test

  • The researcher has to test this prediction using an experiment

  • The NH is not a prediction; the results of the experiment will confirm (or not confirm) the prediction which is that:

    • Drinking caffeine prior to a memory test will result in better performance than drinking water before the test

  • The researcher must then write the NH which assumes ‘no difference’

  • A NH for the above study on the effect of caffeine on memory could be written as follows:

    • There will be no difference in the number of correctly recalled items out of 15 depending on whether participants have drunk 200ml of caffeine or 200ml of water before taking a memory test

  • The researcher runs the experiment and then two options proceed:

    • If the results show no difference between conditions then the NH must be kept/accepted;

    • If the experiment shows a difference in conditions then the NH can be rejected (and the AH is then kept/accepted)

Correlations and hypothesis

• Hypotheses for correlational investigations are written in the same way as experimental hypotheses apart from one crucial difference

  • Instead of using the term 'difference' you have to use the term 'relationship/correlation', e.g.

    • 'There will be a relationship between the number of cups of caffeine drunk and the number of hours slept per night across one week' (non-directional hypothesis)

    • 'There will be a positive/negative relationship between the number of cups of caffeine drunk and the number of hours slept per night across one week' (directional hypothesis)

    • 'There will be no relationship between the number of cups of caffeine drunk and the number of hours slept per night across one week' (null hypothesis)