experimental methods

• research process

  review previous research/theories

  decide on an aim and formulate a hypothesis

  design a study

  conduct research

  analyse and report findings

  add to/ revise theories
• aim - a general statement of what the researcher intends to investigate
• hypothesis - a statement of what you believe to be true.
• The independent variable is manipulated by the researcher.
• The dependent variable is the variable that is measured or observed in a lab experiment.
• types of hypothesis

  • directional - predicts the direction of the difference between the two conditions or groups of people. Used when previous research suggests a particular outcome.
  • non-directional - predicts the direction of the difference between the two conditions or groups of people. Used when there is no previous research or existing research is contradictory
  • null - a statement predicting there will be no difference
• a good hypothesis should be in the future tense and operationalised (clearly defined).

  e.g Participants who believe there is a small audience will make less verbal errors than those who believe there is a large audience
• experiment investigates a difference

  correlation investigates a relationship
• non directional? difference

  there will be a difference in the amount of sweat produced...

  directional? will

  people who eat more chocolate will be significantly heavier
• IV - loud noise -> operationalise it what is the loud noise? i.e shouting

  DV- memory -> what part of the memory? i.e recalling a no. of words
• operationalisation of variables- is the process of defining variables into measurable factors
• control of variables - the extent to which any variable is held constant or regulated by the researcher
• realism - everyday behaviour

  if too much control is applied, results are less realistic to everyday behaviour.
• 4 ways of conducting research

  self reports (questionnaires/ interviews)

  observation of studies (not reliable for realism)

  experiments

  correlations
• more realistic results -> more validity, more control
• extraneous variables - nuisance variables which may interfere with the experiment.

  • variables that are not directly related to the independent variable but may affect the dependent variable
  • i.e any unwanted variable which may have an effect of the DV is extraneous
  • e.g own personal abilities: memorising words may be an extraneous variable, affects memory (which is being measured)
• 2 types of extraneous variables:

  participant variables - to do with differences btwn participants

  e.g age, eyesight, gender, concentration, intelligence, personality.

  situational variables - features of the experimental situation

  e.g noise, weather, time of day, temperature, instructions
• confounding variables -

  • variables that will affect the results of a study (DV) which can't be controlled
  • e.g a study in energy drinks. If the first group drinks water and also happen to be introverts they would be shy, and if the second group happen to be extroverts they would already be very outgoing therefore when the results are analysed we can't be sure whether the energy drinks actually worked or if personality affected the results, so personality is the confounding variable. (this is a 2nd IV) whereas extraneous variables can be controlled or removed.
• if extraneous variables are not controlled, they may become confounding variables.

  confounding do vary systematically with the IV and therefore affect the validity of the results.
• demand characteristics: any cue (sign) from the researcher or situation which might reveal the purpose of the investigation and lead participants to change their behaviour - how they behave is no longer natural

  participants may give a positive response ('please you' effect) or a negative response ('screw you' effect) which may disrupt the experiment.

  can act as extraneous or confounding variables
• investigator effects: any unwanted influence of the researcher/investigator on the outcome of the study

  • can be conscious or unconscious (aware/not they are doing it)
  • maybe in the way the experiment is carried out or in the way it is designed (which participants were selected/ materials chosen)
  • can act as extraneous or confounding variables
• examples of investigator effects

  body language of a researcher, i.e facial expression

  tone of voice when delivering instructions

  interpretation of data

  leading questions - assuming the direction of the answer like gaslighting e.g a-levels are hard, don't you agree? these invite a person to respond in a certain way (may distort data)
• control of demand characteristics + investigator effects

  • single-blind procedure: participants are not aware of the aim of the study and/ or which condition they are in
  • double-blind procedure: neither participants nor researchers who conduct the study are aware of the aims/ hypothesis of the investigation
• control group: people drinking water, people silent

  experimental group: people drinking energy drink, people with music playing
• randomisation: making as many things as possible random to reduce extraneous/confounding variables
• standardisation: giving all participants the exact same environment, information and experience, i.e all procedures are standardised.
• laboratory experiments - an experiment that is performed in a controlled environment. the iv is manipulated by the researcher.

  e.g recalling unconnected lists of words as part of a memory experiment
• • lab strengths:
  • have high control over confounding + extraneous therefore means the researcher can ensure any effect on the DV is due to the manipulation of the IV and so increases internal validity
  • replication is more possible bcs of control therefore no new extraneous variables are introduced. replication is also vital to check whether the finding is valid
• • lab weaknesses:
  • may lack generalisability as the lab environment may be artificial -> in an unfamiliar context participants behave in unusual ways which can't be generalised beyond the research setting therefore has a low external validity.
  • participants are also aware they are being tested in a lab which may give rise to unnatural behaviour due to demand characteristics.
  • the tasks participants are asked to carry out in a lab experiment may not represent everyday experience therefore they have low mundane realism
• quasi experiments - experiment in which the IV is based on a pre-existing/ naturally occurring difference between people e.g gender, age, whether they have autism or not. no one has manipulated this variable, it simply exists

  e.g introverts vs extroverts, man vs woman, autistic vs Down syndrome, people with phobias vs no phobias
• • quasi strengths:
  • controlled often so can be replicated (similar to lab)
  • have high external validity as experiments often reflect natural settings, making results more generalisable
• • quasi weaknesses:
  • cannot randomly allocate participants to conditions + therefore there may be confounding variables
  • cannot claim the IV has caused any observed change as the IV has been deliberately changed (based on an existing difference)
• natural experiments - an experiment in which the IV varies naturally; the experimenter takes advantage of this pre- existing variable as it would have changed anyway. can be tested in a lab or natural environment - the natural part is about the IV not the setting! this type of experiment is often used when it is unethical to manipulate an IV. (someone/thing causes the IV to change, researcher measures the effect of the IV on the DV)

  e.g before+ after a natural disaster, exam results, effects of natural disaster on stress levels, television experiment
• • natural strengths:
  • provides opportunities for research that may not otherwise be undertaken for practical or ethical reasons
  • have high external validity as they involve the study of real- world issues + problems as they happen therefore have high mundane realism
• • natural weaknesses:
  • naturally occurring events may only happen rarely, reducing opportunities for research therefore may limit the scope for generalising findings to other similar situations
  • p's cannot be randomly allocated to experimental conditions (only in independent groups) therefore the researcher may be less sure whether the IV affected the DV
  • such research may be conducted in a lab therefore may lack realism and demand characteristics may be an issue
• field experiments - an experiment which occurs in 'real world' settings rather than the laboratory. the IV is manipulated by the experimenter and as many other variables are controlled. researcher goes to p's usual environment rather than (in a lab experiment) the p's going to a researcher's lab

  e.g an experiment conducted in a busy New York subway where a researcher pretended to collapse, was found that more people helped when the victim was carrying a walking stick than when they smelt of alcohol
• • field strengths:
  • higher mundane realism (than lab) bcs the environment is more natural therefore may produce behaviour that is more valid + authentic especially if p's are unaware they are being studied -> high external validity
• • field weaknesses:
  • ethical issues if p's are unaware they are being studied therefore they cannot consent to this -> such research might constitute an invasion of privacy.
  • confounding and extraneous variables may be difficult to control due to the increased realism
  • replication is often not possible