Presentation on theme: "Investigating Memory Experimental design"— Presentation transcript:
1Investigating Memory Experimental design Jonathan Stirk & Jasper Robinson
2Introduction Aims Objectives To design your own experiment To support the memory component of the first year cognitive courseTo give experience in using a between groups t-testObjectivesYou are going to choose a research topic which can either be conducted on computer or otherwiseYou will design the experiment and the stimuli (to a certain extent) run the experiment and analyse the data
3Introduction Timetable: Today You will work in groups to design your experiment and prepare your stimuli. Before the end of the session your design should be agreed with the lecturer or one of the demonstratorsBetween practical sessionsYou should pilot your experiment, make necessary changes, and try to run all your subjectsAt the next practicalThis session will focus on entering data and running the appropriate analysis. We will be doing the analysis by hand as well as in SPSS, so will show you how to do this and revisit concepts such as variance and standard error. We will finish off with tips on what to include in the write up
4The Experimental Method An experiment is a method of research in which the researcher deliberately intervenes in order to introduce changes into a situation, with the intention of observing the effects of those changes on the processes being studied.The aim of the experimental method is to identify causal relationships between variables.
5Experimental Variables The independent variable (IV)Identified, from theory or elsewhere, as a possible cause of the phenomenon under investigation. During an experiment the value (or level) of the IV is changed by the experimenter in order to observe whether any consequent changes occur to the dependent variableThe dependent variable (DV)Is the variable that is thought to be causally linked to the IV, and which is therefore expected to change its value in response to any changes induced in the IV. During the experiment the DV’s value is measured in order to detect any such changes due to the experimental manipulation (= experimental data)
6Extraneous VariablesIndependent variables which are undesirable and may influence the DV in a random or systematic way which we must try and control. Without some control of these they may add ERROR to the experiment. Systematic extraneous variables (counfounds) are a big problem!Subject variables (e.g. Gender, age, IQ, handedness, etc.)Task variables – arise from the procedures which the subjects are required to perform in an experiment (e.g. Time allowed, task difficulty etc.)Situational variables – all variables found in the environment in which the experiment takes place (e.g. Lighting, temperature, time of day, experimenter’s mood, etc.)
7Controlling Extraneous Variables Unless extraneous variables are controlled they may influence the outcome of the experiment. Without control it is impossible to be sure that the DV was affected by the IV – the extraneous variables may have become confounded with the effects of the IVControl strategies:Design – select the design that minimises possible effectsStandardisation – hold conditions constantRandomisation – distribute probable effects of a variable at random though the experimentCounterbalancing – to remove order effects
8Choosing A Basic Design (2 Condition Experiment) Independent (between subjects) designEach participant is assigned to one of the conditions (but not both)Repeated measures (within subjects) designEach subject is tested twice, once in each condition. Conditions must be counterbalancedMatched subjects designEach subject is given a pre-test and then matched with another subject on the basis of their scores. One member of the pair is then randomly assigned to condition 1 while the second subject is assigned to condition 2
9The Research AreaYour experiments will be taken from one of three hypotheses taken from the memory literature. Only the first is designed to be run on E-prime. If you choose the second or third you will either have to program the experiment yourself, or not use the computers (both of which are acceptable). The three areas are:Lorayne’s imagery mnemonic (E-Prime)Tulving’s encoding specificity principleThe role of organisation in memory
10Lorayne’s Imagery Technique: Putting Names To Faces Cohen (1980) believes that names are particularly hard to remember because there is no semantic relation between name and faceLorayne (1958) suggested that an imagery mnemonic device may help. This has two stages:Make the name more concreteLink the concrete version of the name with the persons faceE.G. You want to recall ex-prime minister Tony Blair’s name when you see his faceChange his name to blain (a pustule, blister or sore)Envision our ex-prime minister with a large blemish on the end of his nose
11Lorayne’s Imagery Technique: Putting Names To Faces Your task is to devise a particular strategy based on Lorayne’s imagery mnemonic and test it out.E.G. Group A are shown the twenty faces stored on E-prime. They are instructed in how to use your mnemonic device. They are later shown the faces again and asked to remember the names.Group B are treated exactly the same but they are not given any advice on how to encode the names.Alt. hyp?Subjects that have been told how to use a mnemonic device will remember more names that the control group.
12Tulving’s Encoding Specificity Principle “The probability of successful retrieval of the target is a monotonically increasing function of informational overlap between the information present at retrieval and the information stored in memory.” – Tulving, 1979, p408.Divers who recalled a list of words underwater, performed better when the words were initially learned under water rather than dry land. When the place/mood/context is consistent in both the encoding and the recall, subjects perform better. –Godden and Baddeley, 1975.E.G. Would you recognise your dentist at Sainsburys?
13Tulving’s Encoding Specificity Principle What about light levels? Temperature? Inside vs. outside? Loud music vs. silence?The design should involve two conditions: a consistent context (between learning and retrieval) and an inconsistent context.E.g. Group A learn a list of words while in a boat on the campus lake. They are later tested again while out on the lake. Group B learn a list of words while in Mooch and are then taken out in a boat to recall them.Alt. hyp: the subjects with the consistent context across encoding and recall will recall the most words.Implications: should you revise in the actual exam room?
14The Role Of Organisation In Memory Which is easiest to learn?List A:ComfortShinyWheelReclineMetalRoundCarSpareHardSeatList B:CarWheelSeatMetalRoundSpareComfortReclineShinyHard
15Bower’s (1969) original hierarchy Bower had subjects learn these words in a structured hierarchy or in an unstructured random list
16The Role Of Organisation In Memory Bower et al. (1969) found evidence in favour of list B.You will replicate the findings of Bower et al. Using your own stimuli.E.G. Group A is given a list of words in a random order without any structure. Later they are asked to recall those words.Group B are given the same words in a semantic hierarchy, and are asked to recall them at a later point in time.Alt. hyp: the group that is given the overt structure will remember more words than the control group.Implications: should your revision notes be structured hierarchically?
17Assessment Criteria The markers will be looking specifically for: Evidence of wide reading – there are a lot of primary sources availableDesign – have you controlled for all extraneous variables? Those you haven’t you should mention in your discussion (e.g.. Word frequency, word length etc.)Results – no raw data. t-test result (standard format). Table OR graphDiscussion – implications to the real worldAppendices – instructions, examples of stimuli, SPSS print out AND t-test workings by hand, raw data