🌸 erm

• an experiment conducted under highly controlled conditions where accurate measurements are possible

• the researcher decides where, when, with who, and in what circumstances the experiment takes place, and using a standardised procedure.

😊 a high degree of control over extraneous variables minimises any extraneous variables, leading to a higher internal validity and a greater likelihood of establishing a cause-and-effect relationship.

😊 greater potential for replicability as the study is carefully designed and variables are highly controlled, allowing other researchers to check for similar results.

🙁 low ecological validity: conditions are artificial/contrived (low mundane realism), making it difficult to generalise findings to real-life situations, beyond the experimental setting.

🙁 high risk of demand characteristics because ppts know they are taking part in a study, they may respond to experimental cues and change their behaviour accordingly, perhaps to please the experimenter. Their behaviour is therefore not entirely natural (confounding variable).

• field experiments are done in the everyday environment of the ppts.

• the experimenter still manipulates the IV.

• ppts are often unaware they are participating.

😊 high ecological validity: research is conducted in the real world (high mundane realism), making it possible to generalise findings beyond the experimental setting.

😊 low risk of demand characteristics: because ppt is often unaware they’re taking part in a study, they’re less likely to respond to experimental cues and change their behaviour to please the experimenter. Their behaviour is therefore more natural.

🙁 less control over extraneous variables, because the study takes place in the real world, reducing the internal validity of the study and making it more difficult to establish cause and effect between the IV and DV.

🙁potentially more time-consuming and expensive.

🙁 difficult to replicate precisely, because variables are not carefully controlled, making it hard to recreate the situation exactly.

• research is conducted in a natural setting

• the experimenter does not manipulate the IV directly; it varies naturally.

😊 high ecological validity: research takes place in real world and no manipulation of variables by the researcher.

😊 low risk of demand characteristics

😊 can be used in situations in which it would be ethically unacceptable to manipulate the IV.

🙁 there is no control over extraneous variables that might bias the results. Cause and effect can therefore be difficult to establish.

🙁 it can be difficult for another researcher to replicate the study in exactly the same way as conditions would have to occur again naturally, which may be unlikely.

• the IV is naturally occurring, but DV may be measured in lab setting.

• the IV is a difference between people that exists (e.g. gender) which means the researcher cannot allocate ppts to conditions randomly.

😊allows for comparisons between different types of people.

😊they’re often carried out under controlled conditions and therefore share the strengths of a lab experiment.

🙁researchers cannot randomly allocate ppts to conditions and therefore there may be confounding variables.

🙁quasi-experiments are often carried out under controlled conditions and therefore share the limitations of a lab experiment.

Milgram (1963) - obedience to unjust authority

• lack of fully informed consent

• deception

• right to withdraw

Hofling et al (1966) - investigated obedience in a hospital setting.

Bickman (1972) - the power of uniform and legitimacy of authority (guard/milkman/civilian)

• lack of consent

• deception

• right to withdraw

• privacy

Rutter (1998) - Romanian orphan study

comparing the levels of serotonin in OCD patients against those without OCD.

any characteristic, number, or quantity that can be measured or counted in experimental investigations.

the variable being measured

the variable being manipulated

putting the variables into a form that can be easily tested or measured by defining them as precisely as possible.

• memory - score on memory test

• stress - blood pressure; levels of adrenaline/cortisol in blood

• illness - absenteeism

a statement of what is being studied and what the study intends to find out.

a precise and testable statement predicting the relationship between two variables, usually derived from a theoretical explanation.

• hypothesis that predicts the direction in which any differences/correlations/associations in results of an investigation are expected to occur.

• only generated if there is previous research upon which to base prediction.

• hypothesis that doesn’t predict the direction in which any difference/correlation/association in results of an investigation are expected to occur.

• generated if there is no previous research.

• predicts that there will be no significant difference/association/correlation found

• any difference found will be due to chance factors alone

refers to the allocation of ppts to the conditions within an experiment

• ppts only take part in one of the conditions, so each group does one level of the IV.

• therefore, two entirely different groups of ppts are compared against each other in terms of their performance.

random allocation: use a random technique, (e.g. picking names out of a hat/random name generator). Ppts will then have an equal chance of being in either condition and ppt variables should be evenly distributed.

😊no order effects: as different ppts do each condition, there are no order effects whereby the order in which the conditions are done may have an effect on the outcome.

😊reduced risk of demand characteristics: ppts are only exposed to one of the conditions, so they’re less likely to guess the purpose of the study and change their behaviour accordingly.

🙁no control of ppt variables/individual differences: for example, ppts in group 1 may have superior memory ability, therefore results may reflect group differences as opposed to the manipulation of the IV.

🙁less economical: twice as many ppts are needed.

• practice effects (positive order effect) - the ppt becomes practiced at the task, which leads to improved performance in the second condition.

• boredom effects (negative order effect) - the ppt becomes bored with the task, which leads to deterioration in performance in the second condition.

• where ppts take part in all conditions within the experiment (i.e. all ppts experience all levels of the IV).

• ppts are compared against themselves.

😊ppt variables/individual differences are controlled as the same ppts are used in each condition and compared against themselves.

😊more economical: fewer ppts are needed, compared to an independent groups design.

🙁order effects: the order of the conditions might affect performance, which can act as a confounding variable (e.g. practice effect or boredom effect).

🙁high risk of demand characteristics: ppts are exposed to both conditions, so are more likely to guess the purpose of the study and change their behaviour to please the experimenter.

• counterbalancing is a technique that can be used to distribute order and practice effects.

• involves changing the order of the conditions from one ppt to the next, so half experience the conditions in one order and the other half in the opposite order.

• ensures that each condition is tested first/second in equal amounts.

• create a time interval between conditions

• vary the stimulus material between conditions (e.g. different word lists of equal difficulty)

• use a different experimental design

ppts are matched across conditions according to certain relevant key characteristics that may impact the DV, such as IQ, age, memory ability.

Bandura’s bobo doll study

😊reduced ppt variables: by trying to ensure that the two groups are similar on some level, the results should be less affected by ppt variables/individual differences and instead be due to the manipulation of the IV.

😊no order effects and less likelihood of demand characteristics, because ppts only take part in one condition, therefore they’re less likely to guess the aim of the study and alter their behaviour accordingly.

🙁difficult to match ppts exactly: it is impossible to control all ppt variables bc you can only match on variables known to be relevant, but an unmatched variable may be vitally important. Even two closely matched individuals will have different levels of motivation/fatigue at any given moment.

🙁time consuming to match ppts: it can take some time for the researcher to identify pairs of ppts that are well matched.

the group of people that the researcher is interested in, from which a sample is drawn - who they will generalise their findings to.

• the group of ppts who take part in the study

• ideally it will be representative of the population so generalisation of findings becomes possible.

• sampling techniques are used to select ppl from the target population and aim to produce a representative sample

• but, they are inevitably biased which can affect population validity of the study.

1. opportunity

2. volunteer

3. systematic

4. random

5. stratified

the researcher selects ppts who are available and willing to take part, asking whoever is around at the time of their study to take part (e.g. asking people passing in the street).

😊convenient: most straightforward sampling technique - it is quick and easy to obtain ppts because they simply select the first suitable ppts readily available to them.

🙁researcher bias: the researcher may avoid people they don’t like the look of and approach those who have more desirable characteristics.

🙁unrepresentative sample: the sample is likely biased as it will undoubtedly exclude certain types of people, because it is drawn from a very specific area, so findings can’t be generalised to the target population.

• ppts select themselves to be part of the sample, often by replying to adverts.

• researcher may play an ad in a newspaper/on a notice board

• ppts may simply raise their hand when researcher asks.

😊easy: creating the sample requires little effort from the researcher, other than creating an advert

😊less chance of ‘screw you’ phenomenon: ppts are willing and likely to take it seriously; less chance of them deliberately trying to sabotage study.

🙁volunteer bias: volunteers may be a certain ‘type’ of person, e.g. more motivated, helpful, and curious, and thus unrepresentative, making it difficult to generalise findings to target population.

🙁volunteers are eager to please and may behave in a way they think is required

• uses a predetermined system to select ppts - every nth member of the target population is selected

• a sampling frame is produced, which is a list of ppl in the target population organised into alphabetical order, for example.

• a sampling system is nominated by calculating the size of the population and then assessing what size the sample needs to be to work out what the sampling interval is.

😊unbiased selection: ppts are selected using an objective system, avoiding researcher bias. this increases the chance of a representative sample, making it possible to generalise findings to the population.

🙁periodic traits: the process of selection can interact with a hidden periodic trait within the population. if the sampling technique coincides with the frequency of the trait, it is neither random nor representative of the target population.

• every member of the target population has an equal chance of being selected - complete list of all members of target population is obtained.

• random techniques could include drawing names from a hat/random number generator.

😊potentially unbiased: the probability of this method producing a biased sample is minimal, because all of the members of the target population have an equal chance of being chosen - free from researcher bias.

🙁potentially biased: could end up with biased sample (e.g. all females selected), particularly if sample size is too small, making sample unrepresentative.

🙁time consuming and impractical: it may be difficult to get full details of a target population and not all members may be available/wish to participate.

• divides population into sub-groups (strata) which are identified as characteristics important for research.

• ppts are selected randomly from the sub-groups.

• the sample must contain all sub-groups in the same proportion as they occur in the target population so it is representative.

😊representative: there is a proportional and randomly selected representation of sub-groups (avoiding researcher bias), making generalisation possible.

🙁time consuming to divide a population into sub-groups and randomly select ppts from each.

🙁requires detailed knowledge of population characteristics, which may be unavailable.

🙁stratification is not perfect: the identified strata cannot reflect all the ways that people are different, so complete representation of the target population is not possible.

• any variable other than the IV that might have an effect on the DV if not controlled.

• they’re nuisance variables and don’t vary systematically with the IV.

• e.g. age, intelligence, noise, temperature

1. participant variables - concern factors like ppts’ age/intelligence

2. situational variables - concern experimental setting + surrounding environment, e.g. temp/noise levels.

3. experimenter variables - concern changes in personality, appearance, and conduct of researcher, e.g. female researchers may gain diff results to male ones.

• a variable under study that is not the IV, but which varies systematically with the IV.

• changes in the DV may be due to the confounding variable rather than the IV.

demand characteristics

any cue from the researcher or from the research situation that makes ppts unconsciously aware of the aims of a study/helps ppts to work out what the researcher expects to find, which may lead to ppts changing their behaviour.

ppts may act in a way they think is expected and over-perform to please the experimenter.

ppts may deliberately under-perform to sabotage the results of the study.

• any effect of the investigator’s behaviour on the research outcome (the DV).

• may include everything from design of the study to the selection of, and interaction with, ppts during the research process.

• ppt is unaware of the research aims and which condition of the experiment they’re receiving.

• this prevents the ppt from seeking cues about aims and reacting to them, thus controlling for demand characteristics.

• both the ppt and person conducting the experiment are ‘blind’ to the aims/hypotheses of the research and which conditions the ppts are in.

• this prevents investigators from unconsciously giving ppts clues as to which condition they’re in and therefore reduces demand characteristics.

• refers to the use of chance wherever possible to reduce the researcher’s influence on design of the investigation.

• attempt to control investigator effects.

standardisation means keeping everything the same for all ppts so the investigation is fair.

• to ensure all ppts have the same experience

• ppts should be tested in the same place, under the same conditions, at the same time of day, and given identical instructions.

• the experimenter should write out a set of instructions ahead of the study, clearly outlining in detail what the ppts are expected to do.

• researchers should present ppts with the instructions to read, or read them out loud to each ppt before the study commences.

• they’re given to the ppts to ensure all of the ppts in the study receive precisely the same instructions.

• ensures each ppt is treated the same and should help to reduce investigator effects.