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Lecture 7

PSYB01 - Lecture 7 Typed.docx

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University of Toronto Scarborough
Connie Boudens

Conducting Experiments Decisions to be made  Who to use as participants and how many  Setting  Manipulation of the i.v.  Measuring the d.v.  Exact procedure  Controlling for expectancy effects  Manipulation checks? - checks to make sure you’re manipulation of the I.V. worked the way you wanted it to  Debriefing  Example: if person on a stand (eye witness) makes contact with the jury how does it affect the perception of how honest the person is? o Forensic psychology looks at eye-witness research – because people are really interested if eye witnesses of a crime can be trust because sometimes that’s the only evidence that the prosecution has o Therefore massive amount of research on how credible eye witness research is and how accurate the things are that eye witnesses reports o Another big area – is court room behaviour = what are the things people do in court rooms that make them more or less credible  This example will be used through-out the lecture: does it matter if the eye-witness makes contact with the jury? Participants  How many? o In general a bigger sample is better up to a certain point – there is an upper limit – because when there is a lot of people even the smallest differences between groups are going to seem like significant differences ( by product of having large numbers) o If you’re going to conduct a study should always try to get as many participants as you possibly can o Participants can be hard to get even if it’s an online survey – therefore don’t usually have to worry about getting too many participants o Statistical consultant can help you figure out your upper limit of participants o In general minimum amount of people in each group = 30 ppl/condition (cell) – don’t really know where this number came o So would have 30 people in the control and 30 different people in the experiment = 60 participants o In a 3x2 design - = 6 different conditions = total participants = 30 x 6 = 180 o When you have too many independent variables and different levels need a lot of participants therefore wound up in a position doing a repeated measures design  Who? – best choice is to use a random sample selected from the population of interest  But most of the time this is not what is done o Convenience  Most psychology studies use this  Usually undergraduates at whatever university the study is being conducted at  However online/internet allows for people from general public from various backgrounds/ages/etc. are now used o Snowball  You ask your friend to ask some of their friends and etc. etc.  It’s a really easy thing to do especially over e-mail – can simply forward the study  Used a lot of times in the early stages of research o Internet-based  Good source of participants but less control over who is going to be filling the surveys out  Can get a broader range of participants  Probability or non-probability sample? – main question to ask is do you need a probability sample or will you be okay with a non-probability sample o If all other things are equal a probability sample will be better because data will be more generalizable – but this isn’t always the goal o May need to get things done more quickly – therefore might not always have time to get a probability sample (very time consuming) o Sometimes probability samples are not really necessary – really depends on the research questions and the resources that are available – large organizations have a lot of resources to be able to get a probability samples Setting – depends on how you’re going to conduct your study o Computer lab space o Lab with computers set up o Mood and ability to make discriminations between two closely related concepts – can all be done on a computer o Regular lab space o Can be any type of space – not necessarily a lab with testing equipment o An office space can be a lab! o Enclosed space where you can control the type of stimuli participants are exposed to & control the people that are coming and going o Secure area where you can keep materials locked up and keep control of things o AV equipped? o Do you need audio visual equipment in your space? o Or any other type of specialized type of equipped – this will dictate what kind of space you use for your experiment o Some AV equipment you can pick up and move – such as gaze-direction equipment – tracks where the person is looking on the computer screen and it gives you an a lot of different types of output – dots of where the person looks, where the persons eyes move while looking at the image o In advertising research they use gaze-direction equipment to see what people focus on the most in the advertisement – want participants to optimally focus on the product o Can also do this for commercials – and different areas of commercial light up depending on what participants looked at o Other equipment is more immobile/large – such as respiration equipment for physiological measures or brain imaging (MRI, cat scans, etc.) – more problematic because time consuming, more money, and more no-shows if testing is off-site o More natural environment o Quasi-experiment in the outdoors, lobby, etc. o Such as Southerners/Northerner experiments utilized a hallway = used natural environment and lab space o Setting depends on what the research question is and what study involves – settings mentioned above = most common settings o Eye-witness and contact they make with jury can have studies in many settings o Ex. in computer setting – have participants watch videos of trials(made-up) with vary levels of the independent variable (eye contact) and have them make a decision about how honest they thing the eye witness is - levels of I.V. vary from no contact to always makes eyes o Ex. with more money & resources – can set up a court room setting and have participants watch how whole thing works out – but this is a lot more time consuming and requires a lot more money – participants can come in in groups as long as they don’t talk to each other Manipulating the IV – doesn’t necessarily mean you’re changing the I.V variable during the experiment just means you’re introducing different levels of the I.V. o Straightforward o Low realism o Usually involve stimuli in the form of photos, video, text, etc. – asking them to make a decision/reaction to stimuli o Ex. eye witness study – if you show your participants video of trials = straight forward manipulation – participant is not really involved in actually study o Presenting people with scenarios – ex. will participants react different to people who take responsibility for what they have done vs. those that don’t – in this case write scenarios depicting these types of people – usually one thing altered in scenarios o Stimuli can be presented by experimenter, or on computer, or in the form of a questionnaire o More commonly done – because involves little participation from experimenter and research assistants and can be done very quickly in different settings o Data can be collected fairly easily & quickly o Staged – also called a high impact experiment o Intended to involve the participant  Participant experiences something – Ex. milligram study on obedience – participant thought he was delivering electrical shocks = high level of realism because research participants thought all parts of experiment were real – authority figure in lab coat, other participants screaming/yelling, strapping in participant, etc.  Line studies on conformity (Ash) – participants are showed 3 lines of different length and show them a different line and asked to match this fourth line with either line A,B, or C – went around the room (8 participants but 7 people are actually confederates) and asked each participant for their opinion  The answer was really obvious – they just want to look at conformity  When most confederates gave right answer so did participant  When most confederates gave wrong answer – participant actually conformed and gave the wrong answer too  Data shows that percentage of times that research participant actually agrees with confederate even when they are wrong is pretty high o Use of confederate(s) o Really high realism – can a chance to see what behaviours people will engage in when they really don’t know what’s going on o A lot harder to conduct because need confederates who act the same every time – this extraneous variable must be held constant otherwise research results can be distorted o Confederates are usually actors but with limited resources this can’t always be done o Takes a lot of time because have to run each participant at one time and takes up a lot of time to set up the experiment o Relies on you depending on a lot of people showing up – confederates, participants, etc. o Requires a lot of money o Might actually do a combination of straightforward manipulation of the I.V. and high impact studies packaged together to show that your idea is really supported – presented as a package to show that your hypothesis is really supported Measuring the DV o Self-report measures o Can be written or verbal; anything that is asking the participant to report on their own thoughts, feelings, etc. o Advantages:  Convenient, easy to construct and administer – especially if its’ something the person can respond to on their own  Paper and pencil – can be administered to more than one person at a time, researcher doesn’t have to be there  Usually using a measure that has already been constructed – such as self- esteem measures in the public domain or can be purchased (copy-righted questionnaires) – already well tested and highly reliable  Allows for greater precision – data is really detailed, with highly valid instruments with high reality - ex. shyness questionnaire  Private behaviours etc. – when observing people can’t look into private behaviours  Thoughts, attitudes not acted on – research indicates that there is a weak link between attitude and behaviours; people may have a lot of attitudes that they may not act on but attitude is what you’re interested in  Drinking, drug use, sexual practice probably have to use self-report measures for because they don’t do these behaviours in public – or ask others in their environment to report on these o Disadvantages:  Rely on honesty, memory (especially with longer span of time)  Social desirability – may not tell the truth if there’s a social desirability component  Doctors automatically double how much drinks you say you have a week Behavioural Measures – a little more complicated, looking at what someone actually does via video tape, one way mirror, and behavioural study o Observable - only look at observable behaviours not restricted to behaviours you can only see with a naked eye o Can include facial expressions, proximity ( to person, object), large movements (such as walking & running) , micro-movements, reaction time o Micro-movements – usually seen using a video tape o Reaction time – usually recorded by computer o Must be (1) concrete (2) codeable- requires to say a behaviour occurred o Advantages: o Visible, external indicators – used as proxy for inner states o Facial expressions – thought of as being representative of a person’s inner states which is usually hard to fake o More spontaneous, less filtered compared to verbal measures/written measures in which people process re
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