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Research in psychology

Research in psychology. 1.3 Experimental methods. Variables. A variable is any characteristics or factor that can vary, e.g : gender, age, grade points, stress, motivation, etc.

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Research in psychology

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  1. Research in psychology 1.3 Experimental methods

  2. Variables • A variable is any characteristics or factor that can vary, e.g:gender, age, grade points, stress, motivation, etc. • Independent variable- the IV produce a change in another variable- deliberately manipulated by the researcher - all other variables are kept constant- Example: new antidepressant medication • Dependent variable- measured after alteration of the IV- is it influenced by the IV?- Example: Did the medication affect the depression?

  3. Operationalized • Operational definition translates an abstract term (variable) into something observable and measureable. • The operational definition gives the variable meaning within a particular study.’ • In precise terms, what is being measured?- Example: aggression vs. how many times the participant will kick the doll during one hour

  4. Hypothesis • Experimental hypothesis is a prediction of how the IV will affect the DV Example: the new therapy will decrease the participants anxiety more than the old one • A null hypothesis is prediction that there will be no change Example: The new therapy will have no effect on the participants anxiety compared to the old one Most often two conditions: • Experimental (treatment) condition- Situation where a variable is being manipulated • Control condition - Situation where a variable is not being manipulated • Is there a significant difference between the two?

  5. Be a thinker p. 27 • Identify the Independent variable and dependent variable in each of the following experimental hypothesis.

  6. Placebo • People who receiving a treatment show a change in behaviour because of their expectations, not because the treatment itself had any specific benefit

  7. Case • Study on the effect of the new antidepressant drug • One group receives the new antidepressant drug and told they receive it – experimental condition (treatment group) • One group receives a placebo pill but told they receive the new antidepressant drug – control condition (group) • Does the antidepressant work better than the placebo?

  8. Experiments • Laboratory experiments+ easy to replicate+ easy to hold variables constant- artificial environment- low ecological validity • Field experiments+ Ecological validity- hard to hold variables constant • Natural experiment+ Unique situations- No control over variables

  9. Experiments • Laboratory experimentsExample:Study on the effect of the new antidepressant drug • Field experimentsExample: Piliavin and Rodin (1969) in the New York subway – investigated helping behaviour regarding sober or drunk person • Natural experimentExample: aggression before and after TV came, stroke victims

  10. Confounding variables (undesirable variables that influence the IV and DV) • Demand Characteristics (aka Hawthorne effect, taken from the Hawthorne Works plant of Western Electric in the US)- Participants act differently because they are in a study and trying to guess what the researcher is after- To counteract: Use single blind control: participants are not told the aim

  11. Confounding variables • Researcher bias (observer bias)- When expectations of the researcher affects the findings, often in subtle and unintentional ways- To counteract: Use double blind control in which both participant and experimenter are unaware if the participant is in the control group or the experimental group

  12. Confounding variables • Participantvariability • Whencharacteristics of the sampleaffect the dependentvarible • To counteract: userandom sampling

  13. Correlation studies – an experiment cannot be carried out but data are collected which show a relationship • Data is gathered that relates to the IV and the DV • If one variable change the other change as well • Positive correlation:- Same change in both variables- both in increase or both decrease- Example: Life expectancy and hours of exercise+ 1 = perfect positive correlation • Negative correlation:- When one variable increase the other decrease- Education and time in jail- minus 1 = perfect negative correlation

  14. Correlation studies • Example: 1. Researcher measures one variable (wealth)2. Researcher measures a second variable (happiness)3. The researcher statistically determines whether wealth and happiness are related. +

  15. Bidirectional ambiguity • Cause-and-effect? • Example: Better social relationships and greater happiness are correlated • But, which causes which? Better social relationships = greater happiness or Greater happiness = better social relationships or is there that another variable responsible for the behaviour? • Correlation between eating ice cream and drowning? = ?

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