Facial Discrimination: The Inversion Effect

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Facial Discrimination The
Inversion Effect

• Traci Lutz
• Independent Study Project Spring 1999

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What will I do?

• Test the ability of one squirrel monkey to learn
  a facial discrimination task on the inversion
  effect

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Why will I do this?

• Research on human facial recognition tasks
• right medial infero-temporal area
• Research on new world primates
• suggest ability to recognize upright faces better
  than inverted faces
• results are not clear

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What is my hypothesis?

• A new world primate squirrel monkey has a
  predisposition to recognize upright faces more
  accurately than inverted faces.

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How will I do this?

• Present two pairs of primate faces to monkey
• One pair in upright form, reinforce the positive
  stimuli
• One pair in inverted form, reinforce the positive
  stimuli
• Train monkey to learn positive stimuli, with
  correct response monkey gets a preferred food
  reinforcement and a check on the score sheet,
  with incorrect response monkey gets no
  reinforcement or punishment and a zero
• Continue trials until monkey decides session is
  over by quitting

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How will I measure this task to get results?

• Score sheets
• checks and zeros for upright and inverted
  positive stimuli

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• Percent correct
• how many in each group correct out of blocks of
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• Plot curves
• from spread sheet to see level of learning

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of times correct for each task
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What did I find?

• This new world primate (squirrel monkey) was able
  to learn the discrimination task on the inversion
  effect for upright faces more accurately than for
  inverted faces.
• This suggests that new world primates may too
  have a predisposition to recognize upright faces
  better than inverted faces.
• In evolutionary terms the new world monkey brain
  is more developed in the same area of the human
  brain for this task.

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Where do I go from here?

• Perform the task with inverted faces only
• to show that learning can occur
• Run same experiment on a number of monkeys with
  opposite positive stimuli
• to show that specific pictures we used or monkey
  were not the sole reason (by chance) for our
  results

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I would like to THANK

• Dr. Brendel
• Dr. Berthold
• Dr. Hakala
• Dr. Newman
• Sarah Banks
• Deanna Bump