The Relationship Between The Relationship Between Participant & InvestigatorParticipant & Investigator

Many investigations create a social Many investigations create a social situation involving both researcher situation involving both researcher and participantand participant

This relationship can affect the This relationship can affect the outcome of the study, threatening outcome of the study, threatening validityvalidity Investigator effectsInvestigator effects Demand characteristicsDemand characteristics

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Types of Investigator EffectTypes of Investigator Effect

Experimenter behaviour effectsExperimenter behaviour effects Experimenters react to PPs as people Experimenters react to PPs as people

(and PPs react to experimenters)(and PPs react to experimenters) Behaviour of experimenter may affect Behaviour of experimenter may affect

attitude of PPs towards the taskattitude of PPs towards the task E.g. conveying dislike for some PPs, E.g. conveying dislike for some PPs,

conveying impression that a task is conveying impression that a task is difficult etc. may affect motivationdifficult etc. may affect motivation

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Types of Investigator EffectTypes of Investigator Effect

Expectancy effectsExpectancy effects The investigator has an idea of what The investigator has an idea of what

outcome to expect in a studyoutcome to expect in a study (1) They may be biased in the (1) They may be biased in the

observations they make, being more observations they make, being more disposed to see things that are in line disposed to see things that are in line with expectationswith expectations

(2) They may communicate their (2) They may communicate their expectations to the PPsexpectations to the PPs

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Types of Investigator EffectTypes of Investigator Effect

Demand characteristicsDemand characteristics Cues that the participants use to Cues that the participants use to

work out the experimental aimwork out the experimental aim They may alter their behaviour as a They may alter their behaviour as a

result either:result either: (1) in line with expectation (pleasing the (1) in line with expectation (pleasing the

experimenter)experimenter) (2) away from expectation (’screw you’; (2) away from expectation (’screw you’;

Masling, 1966)Masling, 1966)

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Sources of Demand CharacteristicsSources of Demand Characteristics

Poor research design decisionsPoor research design decisions E.g. exposing pps to knowledge of both E.g. exposing pps to knowledge of both

conditions when it’s important they conditions when it’s important they don’t know what the IV isdon’t know what the IV is

Researcher behaviour/expectancyResearcher behaviour/expectancy E.g. unintentional reinforcement of E.g. unintentional reinforcement of

desired responsesdesired responses

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Dealing with IssuesDealing with Issues

Pilot the procedurePilot the procedure Get feedback from pilot ppsGet feedback from pilot pps

Did they understand everything?Did they understand everything? Did they realise what the aim was?Did they realise what the aim was? Did they pick up on any particular Did they pick up on any particular

aspects of the researcher’s behaviour?aspects of the researcher’s behaviour?

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Dealing with IssuesDealing with Issues

Standardise everythingStandardise everything I.e. ensure it is I.e. ensure it is exactlyexactly the same for the same for

all the PPsall the PPs Instructions givenInstructions given Procedures followedProcedures followed

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Dealing with IssuesDealing with Issues

Single blind procedure (standard)Single blind procedure (standard) Prevent pps from finding out what the aim Prevent pps from finding out what the aim

isis Problem: can never be sure the Problem: can never be sure the

researcher won’t give cuesresearcher won’t give cues Double blind procedureDouble blind procedure

Prevent pps from being cued at all by Prevent pps from being cued at all by employing a researcher to carry out the employing a researcher to carry out the procedures who does not know the aim of procedures who does not know the aim of the researchthe research

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