The Experimental Method

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The Experimental Method

• (Psychology version)

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Design types used in psychology research

• Observation
• Watch unobtrusively
• Survey
• Ask questions
• Experiment
• Manipulate the situation

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Observation

• Ruback Juieng (1997)
• Do people exhibit territoriality in the parking
  lot by taking longer to back out of parking
  spaces when a car is waiting?

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• Complete this mini-survey using the scale below
• faster just as fast more
  slowly
• 1 2 3 4 5 6 7
• 1. If I am backing out of a parking space and
  someone is waiting, I will back out ____

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• faster just as fast more
  slowly
• 1 2 3 4 5 6 7
• 2. If I am backing out of a parking space and
  someone is waiting and that driver honks the horn
  at me, I will back out ____

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• faster just as fast more
  slowly
• 1 2 3 4 5 6 7
• 3. If someone else is backing out of a parking
  space and someone is waiting, the person will
  back out ____

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• faster just as fast more
  slowly
• 1 2 3 4 5 6 7
• 4. If someone else is backing out of a parking
  space and someone is waiting and that driver
  honks the horn, the person will back out ____

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Ruback Juieng results

• Observation design
• Watch people backing out of parking spaces and
  record what happens.
• 39 sec with a car waiting, 32 sec without.

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Survey

• Landrum (1999)
• Do students have an expectation of grade
  inflation?

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• Think of a course you have taken recently. Rate
  the quality of your work in that course using the
  following scale
• Distinguished
• Superior
• Average
• Below-average
• Failure

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• For the same course, what grade did you deserve?
• A
• B
• C
• D
• F

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Landrum results

• Landrum converted responses to his questions to
  GPAs
• Mean GPA for quality of work 2.43
• Mean GPA for expected grade 3.03
• The difference was significant

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Comparing observation and survey designs

• On surveys
• People lie to look good
• People dont actually know the answer
• Peoples retrospective memory is really bad
• For observation
• People are actually doing it
• Theyre doing it
• Its happening right now

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Comparing observation and survey designs

• For example
• Ruback and Juieng found that people take longer
  in the mild intrusion condition (car waiting, no
  honking). However, on their survey (like the one
  we just did), people responded that they would
  back out faster.
• I just asked you to rate your performance and
  expected grade in a previous class. Now that you
  know your grade, can you really remember your
  expected grade? Hindsight bias research suggests
  that you cant.

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Evaluating observation and survey designs

• For both designs, we cant explain causes of
  behavior. For example
• Do people take longer to back out because theyre
  territorial or because its more dangerous when
  other cars are around?
• Why do people have an expectation of grade
  inflation? (Because they typically get more than
  they earn or because theyve adopted a consumer
  model and think of grades as the product theyre
  paying for?)

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Experiment

• Foertsch Gernsbacher (1997)
• Is the pronoun he used generically really gender
  neutral?

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• The use of he as a pronoun for nouns embracing
  both genders is a simple, practical convention
  rooted in the beginnings of the English language.
  He has lost all suggestion of maleness in these
  circumstances.... It has no pejorative
  connotations it is never incorrect. (Strunk
  White, 1979, p. 60)
• In speech we often solve the problem of the
  generic he by using a plural pronoun...as in
  Everyone brought their books to class. But this
  construction violates the expectations of most
  readers, so it should be avoided in writing.
  (Fowler Aaron, 1983, p. 195)

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• A truck driver should never drive when sleepy,
• even if he/she/they may be struggling to make a
  delivery on time,
• because many accidents are caused by drivers who
  fall asleep at the wheel.

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• A nurse should have an understanding of how a
  medication works,
• even if he/she/they will not have any say in
  prescribing it,
• because nurses must anticipate how a patient will
  respond to the medication.

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Foertsch and Gernsbacher results
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Conclusions

• The choice of method depends on the question,
  keeping in mind
• Ethics
• Feasibility