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Hypothesis' and variables in experiments

INDEPENDENT VARIABLE (IV)- the variable that you can change. 

DEPENDENT VARIABLE (DV) -the variable that you measure 

EXTRANEOUS VARIABLE (EV) -the variable that you cannot control in an experiment. 

HYPOTHESIS: what YOU (the psychologist) predicts what will happen in the experiment and the outcome of research. 

ALTERNATE HYPOTHESIS: a statement that predicts a difference in the results of the experiment. 

NULL HYPOTHESIS: a statement that predicts no change (difference) in the results of the experiment

STANDARDISATION: a way of controlling extraneous variables in an experiment (to keep them the same -they do not fluctuate). E.g. volume of music. 

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designs in experiments

REPEATED MEASURES DESIGN: experimental design in which the SAME group of participants take part in two or more different conditions (e.g. do a test in silence and then with music). 

INDEPENDENT GROUPS DESIGN: an experimental design in which two different groups (e.g. elderly and adolescent people) take part in an experiment (different rooms) with the same conditions. 

EXPERIMENTAL DESIGN: a way of putting participants to conditions in experiments

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sampling techniques

SAMPLE: a small group selected from a target population

TARGET POPULATION: a set of people the psychologist(s) want to generalise their results to. 

REPRESENTATIVE: accurate reflection of a large group. 

RANDOM SAMPLE: sample where everyone in the target population has an equal chance of being picked (e.g. putting names into a hat) 

OPPORTUNITY SAMPLE: where you get participants from available people in your target population. 

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Ethical Considerations in experimens

INFORMED CONSENT: when you allow the participants to know the aim of the study, and they agree to take part in the study. 

RIGHT TO WITHDRAW: you allow the participants to stop participating in the study (or stop study itself). 

CONFIDENTIALITY: the participant can ask to withdraw their names from the data (protecting their identity) 

DEBRIEFING: after the experiment you tell 'debrief' the participants on the aim of the study (v. important) 

E.g. In Milgram's study into obedience, he did not give his participants informed consent, or the right to withdraw. Also ,he did not debrief them afterwards, which could have caused psychological harm. 

In Bickman's study into obedience, he also did not have informed consent from participants and he did not debrief them, which also could have caused the participants embarrassment or psychological harm.)

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Lab/field experiments

LABATORY EXPERIMENT: an experiment carried out in a controlled (artificial)environment that lacks ecological validity. (CAN LEAD TO DEMAND CHARACTERISTICS*)

FIELD EXPERIMENT: an experiment carried out in a natural environment. 

*DEMAND CHARACTERISTICS: when participants guess the aim of the study and change their results to suit or benefit the psychologist's results.  


The artificial setting can lead to participants guessing the aim of the experiment, therefore leading to demand characteristics. 

It lacks ecological validity, as it is set in a heavily controlled setting. 

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closed/open questions

SELF-REPORT: when the participant gives their analysis (results) of the results from the experiment him/herself 

QUESTIONNAIRE: a set of pre-determined questions that are the same for all participants involved. 

CLOSED QUESTIONS: questions where there are set responses to choose from (e.g. multiple choice questions) 

OPEN QUESTIONS: questions where there are no fixed responses, and the participant can answer how they please. 

INTERVIEW: face to face questioning. 

STRUCTURED INTERVIEW:  an interview with pre-set questions 

UNSTRUCTURED INTERVIEW: an interview where the questions depend on the participants' answers. 

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OVERT OBSERVATION: to observe people WITH their knowledge (can lead to demand characteristics and changes in their behaviour due to social desirability) 

COVERT OBSERVATION: to observe people WITHOUT their knowledge

PARTICIPANT OBSERVATION: to observe people while joining in their activities 

NON-PARTICIPANT OBSERVATION: to observe people from a distance. 

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Calculating findings:

VALIDITY: reflecting the truth 

ECOLOGICAL VALIDITY: reflecting a real life situation 

RELIABILITY: consistency; replicates itself 

INTER-RATER RELIABILITY: when two or more researchers agree on their findings 

DEMAND CHARACTERISTICS: cues in an experiment that give away the aim 

OBSERVER EFFECT: when people behave differently in an experiment because they know they are being watched. 

SOCIAL DESIRABILITY: when people change their answers because they say what they believe the psychologist wants to hear. 

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BIAS: only viewing something from a certain perspective 

GENDER BIAS: viewing something from the perspective of one gender (e.g. Haber and Levin's experiment into perception only used male confederates) 

CULTURAL BIAS: viewing things from the perspective of one culture (e.g. Hazen and Shaver's experiment into attachment only used participants from the US) 

EXPERIMENTER BIAS: setting up an experiment and/or interpreting results to fit a certain idea. 

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What is a labatory experiment? 

How do you define experimenter bias? 

What are the differences between independent groups and repeated measures design? 

Which sampling methods are more effective; opportunity or sampling? Why? 

What are the two controls in interviews? 

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