•The general investigative purpose of a psychology study (why the researcher has decided to conduct an investigation) is called its aim.
•A hypothesis is a precise and testable statement of what the researcher predicts will be the outcome of the study. In an experiment this is called the experimental hypothesis.
•In a correlational study the hypothesis is called a research hypothesis, and it will predict a relationship between two variables.
•A research hypothesis is called an alternative hypothesis.
An alternative hypothesis is either:
•Directional (one-tailed): predicts the direction of the effect expected (e.g. ‘using visual imagery will improve how well words are recalled’), or
•Non-Directional (two-tailed): predicts an effect but does not specify its direction (e.g. ‘using visual imagery will affect how well words are recalled’).
•Every hypothesis also has a null hypothesis. This predicts that there will not be a difference; any difference is due to chance.
Designing experimental research
Independent groups design
Each participant (P) is involved in only one condition of the experiment; the P is selected randomly for either the experiment or the control condition.
Advantages: Can be used in wide range of situations, fairly easy to run, no order effects from P’s becoming skilled, bored or fatigued.
Disadvantages: Individual differences between groups may distort findings (random allocation to conditions helps reduce this risk); require fairly large sample size because each P is used only once.
Repeated measures design
Each P is involved in all conditions, the same Ps are used in experimental and control groups.
Advantages: Economical in use of Ps, no risk of participant variables confounding the findings as same Ps used in each condition,
Disadvantages: Demand characteristics- Ps have more opportunity to guess the purpose of the study, order effects- performance could be affected by boredom or fatigue. Problem of order effects can be overcome by using: counterbalancing- half the Ps perform first in condition A and half perform in condition B.
Matched participants design
Each P in the experimental condition is matched on relevant variables (age, intelligence) with a P in the control condition. Members of the pairs are randomly allocated to conditions.
Advantages: No order effects, reduced risk of individual differences between Ps confounding the findings,
Disadvantages: Matching Pairs of Ps is time-consuming and expensive, requiring a large number of Ps to begin with; difficult to ensure adequate matching of the pairs.
Designing naturalistic observations
Observers usually sample the behaviour to be recorded and interpreted. Ways of doing this include:
Time interval sampling- observe and record what happens only during specified time, such as for the first 15 minutes of each hour.
Event sampling- observe and record only the events of interest, such as every instance of aggressive behaviour.
Designing questionnaires surveys and interviews
Issues that need to be resolved when designing these studies include:
Type of questions e.g. open or closed
Clarity in wording to avoid unnecessary jargon or vagueness
Avoiding ‘leading’ questions
Factors associated with research design
Numerous factors need to be considered if a study is to be well designed
•Procedures and instructions should be standardised. For example, all Ps in the same condition in an experiment should receive exactly the same instructions.
•Potentially confounding variables should be held constant across experimental conditions or eliminated.
•Variables should be operationalized, i.e. defined in terms of the exact steps (operations) taken to measure them. For example, ‘the number of words recalled immediately after learning’ could be used as an operational definition of STM.