control of variables

• control-confounding variables: a class of psychology students conducted a study w/ the aim of finding out whether participants could do their homework effectively while in front of the TV
• control-confounding variables: the IV was whether the TV was on or not, the DV was the participants' score on the memory test, if the TV was a distraction the 'TV off' group should do better on the test
• control-confounding variables: but consider this suppose it happened that al the participants in the 'TV off' condition did the memory test in the morning and all the participants in the 'TV on' condition did the memory test in the afternoon
• control-confounding variables: people generally are more alert in the morning and this might mean that it was the time of day rather than the lack of noise that caused the change in the IV, time of day may then be regarded as a confounding variable
• control-confounding variables: the experimenter may claim that the IV caused a change in the DV but in fact this may not be the case - changes in the DV may actually be caused by confounding variables
• control-confounding variables: the experimenter may not have actually tested what they intended to test, instead the influence of a different variable has been tested, the experimenter must be careful to control any possible confounding variable(s) in this case participants in both conditions should do the test at the same time of day
• control-extraneous variables: some students will have better memories than others, it is unlikely that all people w/ better memories would end up in the 'TV off' group
• control-extraneous variables: if they did, this would act as a confounding variable, but it is more likely that this variation is a nuisance variable because we can never be sure that people w/ good (or bad) memories are distributed evenly across the 2 conditions
• control-extraneous variables: the extraneous variable of memory ability just makes it more difficult to detect an effect because other factors have an influence
• control-extraneous variables: the nuisance variables are called extraneous variables they should be controlled if possible because they may affect the DV but not in a systematic way, they are 'extra'
• realism: the aim of any psychological study is to provide information about how people behave in 'real life' - the everyday settings in which life is lived
• realism: if the set-up of a study is too artificial or contrived then the participants will not act as they would normally
• realism: e.g. the study by Loftus and Planer investigated eyewitness testimony by showing participants a film of a car accident and asking questions about the speed of a car, but how realistic is this? is watching the film the same as seeing a real accident?
• realism: many things affect the realism of a psychological study, the term mundane realism refers to how an experiment mirrors the real world, 'mundane' means 'of the world' commonplace, ordinary, so lack of mundane realism means something is not like everyday experience
• realism: watching a car accident on film lacks mundane realism because it is not like everyday experience and this means that the results of the study may not be very useful in terms of understanding behaviour in the real world
• generalisation: the point of realism in psychological research is to be able to generalise the results beyond the particular unique research setting - in particular to be able to understand behaviour in everyday life (the 'real world')
• generalisation: if the materials used in the study are contrived (such as film clips) then the behaviours observed may lack realism
• generalisation: if the environment in which a study is conducted is contrived and especially if participants are aware they are being studied the participants behaviour may lack realism
• generalisation: even if the environment and materials are 'natural' or real (i.e. high realism) a study can still lack generalisability e.g. if all the participants in a study are American university students it may not be reasonable to generalise the findings to the behaviour of all people because Americans (and students) have unique characteristics that may set them apart in some way from other people
• generalisation: the question psychologists are always asking themselves is 'to what extent can i generalise these findings to everyday life?'
• about experiments: the term validity refers to how true or legitimate something is an explanation of behaviour, it involves the issues of control, realism and generalisability
• about experiments: students often believe that validity is about 'being correct', this is both right and wrong, it is right because a researcher seeks to find out whether their hypothesis is true i.e. correct, but it is wrong if you think that being correct means finding out that the predicted expectations have been confirmed
• about experiments: validity is not about confirming your expectations, validity can be separated into internal validity and external validity
• about experiments: internal validity is about control and realism, external validity is about being able to generalise from research participants to other people + situations
• internal validity: internal validity concerns what goes on inside a study
• internal validity: whether the IV produced the change in the DV (or did something else affect the DV such as a confounding variable?)
• internal validity: whether the researcher tested what they intended to test, e.g. if you want to find out whether watching TV affects the quality of homework you cannot be certain you are testing 'watching the TV; just by having the TV on (the person may not be watching it)
• internal validity: whether the study possessed (or lacked) mundane realism
• internal validity: to gain high internal validity researchers must design the research carefully, controlling confounding and extraneous variables and ensuring that they are testing what they intended to test
• external validity: external validity is affected by internal validity - you can't generalise the results of a study that was low in internal validity because the results have no real meaning for the behaviour in question
• external validity: the place where the research was conducted (ecological validity) it may not be appropriate to generalise from the research setting to other settings, most importantly everyday life
• external validity: the people who are studied (population validity) if a research study involved just students or all men or only Americans etc, then it may not be appropriate to generalise the findings to all people
• external validity: the historical period (historical validity) if a study was conducted in the 1950s it may not be appropriate to generalise the findings to people today because many other factors affect behaviour now
• testing involves: writing a hypothesis, designing a study to test the hypothesis, collecting data, analysing results, questioning the validity of the study and drawing conclusions = the scientific cycle