research methods OCR Experiments

Created by: harleen sandhu
Created on: 02-01-13 15:16

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Experiments
- hypothesis
  - ( experimental)alternative hypothesis - predicts the effect will occur,
    - one tailed (directional)
      - predicts the expected direction of the results - can only go one way
    - two tailed ( non-directional)
      - doesn't predict the expected direction of the results - can go either way
  - null hypothesis - there will be no effect, no different, no relationship
- types of experiments
  - field experiment - aired out in the natural environment ( real world situation)
    - advantages: high ecological validity, people may behave more naturally ( higher realism), easier to generalise from results, can avoid demand characteristics.
    - disadvantages: weak control over extraneous variables, difficult to replicate, sampling can be a problem, not practical, difficult to debrief, difficult to gain consent, time consuming and expensive.
  - natural/quasi experiment - where the independent variable is not manipulated by the researcher but occurs naturally
    - advantages: participants are unaware they are taking part in the experiment, high increased ecological validity, enables psychologists to see real problems, less chance of demand characteristics or experimenter bias interfering,
    - disadvantages: independent variable isn't controlled by the experimenter, cant be replicated, participants may be aware of being studied (reduces naturalness)
  - lab experiment - an artificial environment with tight controls over variables
    - advantages: can control variables, easy to replicate, record and analyse, quick and cheap, less time consuming, high validity, easy to see cause and effect, extraneous variables are minimised.
    - disadvantages: not always possible to control variables, confounding variables ( affects results and gives false set of results), experimenter effects, need consent of participants, low ecological validity, demand characteristics ( participants may know about the experiment and try to behave differently.
- experimental designs
  - independent measures- using different participants in each condition
    - disadvantages: participant variables- the differences between participants in the group may effect results. e.g age, gender, social background, more participants are required because each is used only once.
    - advantages: avoids order effect-if a person is involved in several tests they may become bored/tired and fed up by the time they come to the second test. demand characteristics is less of a problem as participants should be likely to guess the aim.
  - repeated measures-using the same participant in each condition
    - disadvantages: order effects are more likely to occur e.g learning or boredom, demand characteristics may be a problem as participants do both conditions and may guess the aim of the study and act differently, participants may not decide to return for the next part of the experiment
    - advantage: participant variables-individual differences are shown such as intelligence or past experiences etc, few participants are required because people are used more than once.
  - matched pairs-using different but similar participants in each condition(e.g matching the participants with the same/similar characteristics)
    - advantages: participant variables are kept more constant between conditions, order effects are avoided as the participant only participates in one condition, demand characteristics- less of a problem as the participants are only in one condition, same test can be used
    - disadvantages: time consuming trying to find matched pairs, impossible to match people exactly, participants can only be used once, more participants are required because each one is only used once.
- control in experiment - variables
  - IV and DV
    - IV is what you change (x- axis) AND DV is what you measure (y-axis)
  - extraneous and confounding
    - extraneous variable: a variable which could influence the DV and spoil the experiment confounding variable: a variable which has an unintentional effect on the DV
  - ( extraneous variables) situational and participant
    - situational: variables which arise from the situation/environment e.g noise/ temp
      - controlling situational variable
        order effects can be controlled using independent measures design
        
        controlling effect and demand characteristics of investigators are hard
        standardised instructions: a way of controlling investigator effects because they ensure that all participants have some instructions and no hints are given.
        
        single blind- participants are not told the true aims of the study, this discourages them from selecting certain cues and altering their behaviour.
    - participant: arise from the participants behaviour and/or their characteristics
      - controlling participant variables
        con be controlled by using repeated measures design or using matched pairs design where participants are paired by matching them on key personal variables.
- reliability and validity
  - reliability: can use the rest-retest method or inter-rater reliability to check reliability
  - validity: validity of measurements concerns whether an experimenter was testing what he/she intended to test. Also.. ecological validity- findings of a study can be generalised to everyday life determined by control and realism
- ethics
  - can still obtain informed consent
  - deception- if you tell participants the true aims of the experiment beforehand this may effect how they behave, so the experimenters have to give false information
  - experimenters must avoid psychological harm
order effects can be controlled by counterbalancing which ensures each condition is tested first of second in equal amounts.
cause and effect- researcher deliberately alters one variable (IV) to see what effect it has on the (DV)

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research methods OCR Experiments

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