Laboratory experiments

What makes a laboratory experiment different to a laboratory study?

An experiment must have an IV and a DV.

Non-experimental research can also be conducted in a lab

What is the argument between laboratory and realism experiments?

• The greatest control is achieved in a laboratory experiment, but it may be difficult to generalise to other environments.

• Some argue that we can only truly discover cause & effect in natural environments.

• If the set up is too artificial/controlled, participants may not act normally

MUNDANE REALISM: how an experiment mirrors the real world

GENERALISATION: if you’re able to take results and how they relate to real-life applications

Key features of a laboratory experiment

• Controlled, artificial setting

• Standardised procedures

• At least 1 IV & DV = 2 or more conditions (look for difference between 2 conditions)

• Participants often know they’re in a study

• Nomothetic research method: more participants tested (=more generalisable results)

Key features of a field experiment

• More natural environment

• Variables harder to control, but IV still manipulated

• Participants are less likely to know they’re taking part

Key features of a quasi experiment

• Not a true experiment (IV not deliberately manipulated, cannot claim changes in DV is caused by IV)

^ natural experiments

^difference studies

What is an experiment design, and give 3 examples

How we organise our participants into groups; the way in which the levels of IV are delivered

• Independent groups/measures design

• Repeated measures design

• Matched pairs design

What is independent groups/measures design? Give disadvantages and how to deal with them

Participants are grouped & each group does 1 level of IV

• Cannot control effects of participant variables and therefore confounding variables

• ^ randomly allocate participants to conditions

What is repeated measures design? Give disadvantages and how to deal with them

All participants receive all levels of the IV

• ORDER EFFECT: order of conditions may affect performance

• PRACTICE EFFECT: may do better because they’re less anxious, OR

• BOREDOM EFFECT: bored of doing the test again

• ^ Counterbalancing

What is matched pairs design? Give disadvantages and how to deal with them

Use 2 groups of participants, but match them based on key characteristics that’re believed to affect DV.

• TIME CONSUMING: difficult to match everyone

• Can’t control all participant variables

• ^ Restrict number of variables

• ^ Pilot study

What is counterbalancing?

Used to control order effects in experiments or a repeated measures design.

Methods:

1. AB or BA (group 1 does AB, group 2 does BA)

2. ABBA (everyone does each condition twice)

What is a standardised procedure?

Ensures each participant does the same thing in each condition

(If not, results may vary because of these changes and not the IV)

What are the strengths of laboratory experiments?

• High level of control

• Extraneous variables can be controlled

• Accurate measurements & standardised collection of data

• Standardised procedures, replication is possible

• Quantitative data=less subjective

What are the weaknesses of laboratory experiments?

• Low-ecological validity (may not represent real life accurately)

• Participants are aware they’re in a study

• Demand characteristics

• Experimenter effects- bias