AQA · A-Level · Psychology
Course version: 7182-2025 · Exams from 2027
Scientific processes: Hypotheses: directional and non-directional.
A prediction is directional, or one-tailed, when it says which way the results will fall: participants recall more words in silence than with music.
Checked against the AQA 7182-2025 specification (opens in a new tab) on .
- Point 2 of 17
- 3 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
A prediction is directional, or one-tailed, when it says which way the results will fall: participants recall more words in silence than with music. It is non-directional, or two-tailed, when it predicts a difference or a relationship but not which group does better. The choice is not free. Where previous research points consistently one way, a direction is justified; where findings are mixed, contradictory, or the area is new, leave the direction out, because a one-tailed prediction that goes the wrong way cannot be supported however large the effect. Alongside sits the null hypothesis, which states there is no difference beyond chance, and it is the null a statistical test allows you to reject at the 0.05 level. Either type must name both conditions and an operationalised DV.
What earns the marks
- States that a directional hypothesis predicts the direction of the difference or correlation, using words such as more, less, faster or positive.
- States that a non-directional hypothesis predicts a difference or relationship without specifying which way.
- Justifies the choice by whether previous research is consistent, or mixed and contradictory.
- Writes the hypothesis with both levels of the IV named and the DV operationalised.
- Links the wording to the null hypothesis and to the decision made after a statistical test.
Common mistakes and how to put them right
Calling a hypothesis directional when it only says one variable 'affects' or 'influences' another, which states no direction.
Predicting a difference and then, in the same sentence, saying which group is higher, producing a muddled hybrid.
Choosing a direction on a hunch when the stem says previous findings are inconsistent.
Confusing a correlational hypothesis, which needs a positive or negative relationship, with an experimental one predicting a difference.
Exam tips
- Read the stem for the phrase 'previous research has found', which is the examiner signalling that a direction is expected.
- For correlations, write 'there will be a positive correlation between X and Y', with both co-variables measured, not manipulated.
- Keep it to one sentence in the future tense; a paragraph of reasoning earns nothing here.
Try the lesson
The start of the Scientific processes: Hypotheses: directional and non-directional. lesson, made from checked teaching notes for this specification point.
Have a go first
When is a researcher most likely to choose a directional hypothesis rather than a non-directional hypothesis?
Listen
A prediction is directional, or one-tailed, when it says which way the results will fall: participants recall more words in silence than with music. It is non-directional, or two-tailed, when it predicts a difference or a relationship but not which group does better. The choice is not free. Where previous research points consistently one way, a direction is justified; where findings are mixed, contradictory, or the area is new, leave the direction out, because a one-tailed prediction that goes the wrong way cannot be supported however large the effect. Alongside sits the null hypothesis, which states there is no difference beyond chance, and it is the null a statistical test allows you to reject at the 0.05 level. Either type must name both conditions and an operationalised DV. A strong answer earns marks for these points. States that a directional hypothesis predicts the direction of the difference or correlation, using words such as more, less, faster or positive. States that a non-directional hypothesis predicts a difference or relationship without specifying which way. Justifies the choice by whether previous research is consistent, or mixed and contradictory. Writes the hypothesis with both levels of the IV named and the DV operationalised. Exam tip: Read the stem for the phrase 'previous research has found', which is the examiner signalling that a direction is expected.
Key words
Say what each word means before you turn the card.
Directional hypothesis
Try answering aloud or in your head before turning the card.
Non-directional hypothesis
Try answering aloud or in your head before turning the card.
Null hypothesis
Try answering aloud or in your head before turning the card.
See every definition
- Directional hypothesis
- A prediction that says which way the results will fall, for example that participants recall more words in silence than with music.
- Non-directional hypothesis
- A prediction that a difference or a relationship will occur but does not say which group does better.
- Null hypothesis
- A statement that there is no difference beyond chance, which a statistical test allows you to reject at the 0.05 level.
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