Experiments Flashcards
independent measures design
Involves using different participants in each condition
Strength of of IMD
-no order effects (practise, fatigue, bored)
-reduced exposer to demand characteristics ( cant work out the aim of the study and change behaviour)
weaknesses of IMD
-Individual differences
-more participants needed(harder to find and less ethical )
Repeated measures design
Involves using the same participants in each condition of the experiment
Strengths of RMD
-individual differences/ p’s variables are the same
-uses less participants
Weaknesses of RMD
-order effects could change result
- P’s are more exposed to demand characteristics
Matches pairs design
involves using different but similar participants in each condition
Strengths of MPD
order effects and demand characteristics are less of an issue
weaknesses of MPD
Hard to get identical people/twins
-using similar people but they aren’t the same
-time consuming
counter balancing order effects
alternating the order in which participants do the conditions of the experiments. e.g. half of the participants would complete condition A and then condition B and then the other half would complete condition B first and then condition A (ABBA)
single blind procedure for demand characteristics
participant isn’t awear of the research aims or which condition of the experiment they are receiving.
double blind procedure for demand characteristics
prosects against both demand characteristics and experimenter bias, ensures neither researcher working with participant nor the participant themself knows what conditions an individual is in.
extraneous variable
Outside factors that are not the IV that effect the outcome of the experiment
situational variable- outside infuses on the experiment such as time of day, weather, notice and type of room experiment takes place etc. Order effects such as practise boredom and fatigue often occur when a participant is asked to undertake a task more than once e.g. the control and experimental condition in a RMD experiment. for example if an experiment took place at the end of the day they may be more tired than if they did it at the start of the day and fatigue an extraneous variable could effect the results, so could the nose in the room that the experiment was conducted in
Participant variables- are individual differences between p’s such as levels of intelligence, age, gender, social class, fitness etc.. Researcher can do little to control this but can carefully select participants.
Control of situational variables
Standardisation- all instructions given, procedures followed, scoring techniques and environment much be identical for each participant.
Counterbalancing- (other flashcard on this)
Randomisation- Order of tasks, presentation of data etc. is decided on the toss of a coin or another random method of selection to control order effects
Aim
Statement of what is going to be studied, not a prediction of expected findings.
Hypothesis
A statement or a prediction of what results you expect to find after your experiment
Alternate/ experimental hypothesis
States that something is going to happen e.g. people with bikes will be fitter than people without bikes
Null hypothesis
The prediction that no effect will be found in the research e.g. there will be no difference/effect/ relationship due to the IV. e.g. there will be no difference in the fitness levels of people with and without bikes, any differences will be due to chance factors.
One tailed/ directional hypothesis
Predict what direction the change will be in. It’s precise and used words such as faster/slower. Bigger/smaller. e.g. alcohol decreases reaction time
Two tailed/ non directional hypothesis
Predicts change but does not specify direction, its non specific and used words effect, change, difference e.g. alcohol will effect reaction time
Operationalisation
Need to show how your measuring your variables, both IV and DV for example without operationalise- People work better in quite rather than noisy conditions- ‘work better= obtain a higher score on memory test. quite= no sound (silence) Noisy= radio playing- people obtain a higher score on a memory test when tested in quite (silence) rather than noisy (radio playing) conditions.
Lab experiment
researcher has strict control over variables and uses standardised procedures in a controlled environment and researcher manipulates the IV
Strengths of a lab experiment
-Manipulation of IV can indicate cause and effect relationship
-All other variables can be ‘held constant’ which means increased control and accurate measurement
-standardised procedures means that the experiment can be replicated at any time in the future
Weakness of a lab experiment
- artificial conditions may produce unnatural behaviour and results may lack ecological validity ( what happens in the lab may not be a reflection of real life)
-Some situations cannot be created in lab conditions
Field experiment
Takes place in the subjects own natural environment. P’s are not usually awear that they are participating in an experiment, but the research still manipulates the IV
Strengths of a field experiment
-higher level of ecological validity because surroundings are natural
- less likely of demand characteristics as people are unaware of the research taking place
Weakness of field experiment
-lack of control can mean that it is difficult to assume that the variable manipulated(IV) was actually influencing behaviour and it wasn’t something else.
- a degree of secrecy or deception may be required and therefore there are ethic problems of consent deception
Quasi experiment
The researcher makes use of naturally occurring variables e.g. age, sex, occupation. Not a true experiment because the scientist cannot really manipulate the IV
Strengths of a quasi experiment
-allows researchers to investigate areas that otherwise may be unavailable to them such as drug users, alcoholics, victims of abuse without creating situations which are harmful to participants
- high level of ecological validity since the change in the IV is a natural one
Weaknesses of quasi experiment
-there is no control over the participant in terms of social setting how they were brought up lifestyle etc. and these may be confounding variable which influences behaviour.
-difficult to replicate exactly.
- may be subject to bias if p’s know they are being studied
Reliability
Consistency of a measure is considered reliable if we get the same result repeatedly. A research method is considered reliable if we can repeat it and get the same result
Test-retest reliability
Repeat at a later date, taking the same test again at different points in time. e.g. An IQ test would be given at least twice at different points in time.
Validity
Validity is the extent to which a test measures what it claims to measure
Internal validity
Refers to the extent to weather the IV caused the effect of the DV or weather other factors was responsible. Extraneous variables threaten validity
