Experiments

What is the definition of an aim?

A general statement of what the researcher intends to investigate (the purpose of the study)

What is the definition of a hypothesis?

A clear, precise testable statement that states the relationship between the variables to be investigated (stated at the start of any study)

What are the 3 different types of hypotheses?

• Directional hypothesis: states the direction of the difference or relationship

• Non-directional hypothesis: doesn’t state the direction of the difference or relationship

• Null hypothesis: states no relationship exists between the two variables being studied

What is the definition of the experimental method?

Involves the manipulation of an IV to measure the effect on the DV (can be either laboratory, field, natural or quasi)

When do researchers use a directional & non-directional hypothesis?

• Directional hypothesis: when the findings of previous research studies suggest a particular outcome

• Non-directional hypothesis: when there is no previous research, or findings from earlier studies are contradictory

What is the definition of operationalisation?

Clearly defining variables in terms of how they can be measured

What is the definition of an extraneous variable?

Any variable, other than the IV, that may affect the DV if it is not controlled (think extraneous → extra)

What is the definition of a confounding variable?

A type of extraneous variable that affects the DV, is related to the IV, & makes it unclear what is actually causing the observed effect (think confounding → confusing)

What is the definition of demand characteristics?

Any cue from the researcher/research situation that may reveal to the participant the aim of the study, leading to them changing their behaviour

What is the definition of investigator effects?

Any effect of the investigator’s behaviour (conscious or unconscious) on the research outcome → includes everything from the design of the study, to the selection of, & interaction with, participants during the research process

What is the definition of randomisation?

The use of chance to control for the effects of bias when designing materials & deciding the order of conditions

What is the definition of standardisation?

Using exactly the same formalised procedures & instructions for all participants in a research study

What is the definition of an experimental design?

The difference ways in which the testing of participants can be organised in relation to the experimental conditions

What is the definition of an independent groups design?

Participants are allocated to different groups where each group represents one experimental condition

What is the definition of a repeated measures design?

All participants take part in all conditions of the experiment

What is the definition of a matched pairs design?

• Pairs of participants are first matched on some variable(s) that may affect the DV

• Then one member of the pair is assigned to condition A & the other to condition B

What is the definition of random allocation & counterbalancing?

• Random allocation: controls for participant variables in an independent groups design, which ensures each participant has the same chance of being in one condition as any other

• Counterbalancing: controls for order effects in a repeated measures design (half the participants experience the conditions in one order & the other half in the opposite order)

What are the strengths & limitations of an independent groups design?

Strengths:

• no order effects

• reduced risk of demand characteristics

Limitations:

• less economical as more participants are required

• individual differences/participants variables

What are the strengths & limitations of a repeated measures design?

Strengths:

• more economical as less participants are required

• no participant variables/individual differences

Limitations:

• increased risk of demand characteristics

• order effects (performance may improve due to practice or worsen due to fatigue)

What are the strengths & limitations of a matched pairs design?

Strengths:

• no order effects

• reduced risk of participants variables/individual differences

Limitations:

• more time-consuming & expensive

• individual differences as participants can never be exactly matched

What is the definition of a laboratory experiment?

Occurs in a controlled environment within which the researcher manipulates the IV & records the effect on the DV, whilst maintaining strict control of extraneous variables

What are strengths & limitations of a lab experiment?

Strengths:

• high internal validity, due to high control over extraneous variables → cause & effect relationship can be established

• high replicability due to high level of control & standardisation

Limitations:

• lacks generalisability → artificial environment, which may encourage unnatural behaviour

• low ecological validity & mundane realism → tasks unrepresentative of everyday life

• demand characteristics more likely → participants know they’re being tested

What is the definition of a field experiment?

Occurs in a natural setting within which the researcher manipulates the IV & records the effect on the DV

What are strengths & limitations of a field experiment?

Strengths:

• high ecological validity & mundane realism → environment is more natural

• less chance of demand characteristics → produces more valid & authentic behaviour

Limitations:

• cause & effect relationship is harder to establish due to loss of control of extraneous variables

• precise replication is often not possible

• ethical issues (e.g. lack of informed consent & privacy) → participants are unaware they’re being studied

What is the definition of a natural experiment?

The change in the IV is not brought about by the researcher but would have happened regardless; researcher simply records the effect on the DV

What are strengths & limitations of a natural experiment?

Strengths:

• provides opportunities for research that may not otherwise be undertaken for practical or ethical reasons

• high external validity → involve the study of real-life issues & problems as they happen

Limitations:

• reduced opportunities for research → a naturally occurring event may only happen very rarely, limiting generalisation

• participants are not randomly allocated to experimental conditions → cause & effect relationship is harder to establish

What is the definition of a quasi-experiment?

A study in which the researcher does not manipulate the IV, instead it is naturally occurring

What are strengths & limitations of quasi-experiments?

Strengths (often carried out under controlled conditions):

• high internal validity, due to high control over extraneous variables → cause & effect relationship can be established

• high replicability due to high level of control

Limitations:

• confounding variables → participants cannot be randomly allocated to conditions