Unit 2: Colour Vision

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Unit 2 Colour Vision

• Quiz 1
• Warm-Up Exercises
• Lab Activity
• Data Sheet
• Analysis
• Debriefing

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Quiz 1
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Warm-Up Exercises
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Warm-Up Exercises

• Data Types
• Nominal
• Name it, sort it, count it
• Ordinal
• Ordered, not necessarily numbered or equal
• Interval
• Numerical with equal intervals, measurable
  differences
• Ratio
• True zero, mathematical manipulation possible

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Warm-Up Exercises

• Measures of Central Tendency (averages)
• Textbook pp. 743-744
• Mean (commonly called average)
• M ?X N where
• X the scores,
• ?X total of the scores
• N number of scores
• Median
• Middle score (put scores in order first)
• Mode
• Most common score

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Warm-Up Exercises

• Exercise 3
• Code excellent as 1, very good as 2, good
  as 3, average as 4, poor as 5, very poor as
  6, and extremely poor as 7.
• So, if 3 people rated the BP as excellent, the
  data would include three 1s if 4 people selected
  very poor, the data would have four 6s
• 1 1 1 2 2 3 3 3 4 4 4 5 6 6 6 6 7
• M 3.76 Median 4 Mode 6

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Warm-Up Exercise

• Your Labs Data
• 1 Excellent 3
• 2 Very Good 2
• 3 Good 3
• 4 Average 3
• 5 Poor 1
• 6 Very Poor 4
• 7 Extremely Poor 1

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Lab Activity
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Retinal Mapping Data
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Analysis Sheet 1

• Mapping the Norms
• Use colour pencils to trace the perimeters of the
  different colours zones on this normative map.

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Analysis Sheet 2

• Use means for each colour for each angle from the
  data collected from your subject to superimpose
  his or her map on this normative map.
• Use the appropriately coloured pencil to place
  dots on the rays for the angles tested (0, 45,
  90, 135, 180, 225, 280, 315).
• Connect the dots using a straight-edge.
• Ignore the normative lines on this map.

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Debriefing
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Parts of the Eye
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Debriefing

• Gross Anatomy of Retina
• Textbook pages 176-179
• Cones
• Mediate chromatic vision
• Centrally located (around the fovea)
• Rods
• Mediate achromatic vision
• Peripherally located

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Rods and Cones
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Debriefing

• Layers of the Retina
• Passage of Light
• Ganglion cells ? Bipolar/Amacrine cells ?
  Receptor cells
• Passage of signal
• Receptor cells ? Bipolar/Amacrine cells ?
  Ganglion cells ? Optic nerve (axons of ganglion
  cells) ? Brain

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Retina
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Debriefing

• Methods of Threshold Limits
• Textbook pages 171-175
• Absolute threshold lowest intensity at which
  subject detects the stimulus 50 of the time
• Difference threshold smallest difference
  between 2 stimuli that a subject can detect 50
  of the time
• Noise irrelevant or competing stimuli
• Random sampling
• Subject should not be able to predict stimulus
• Method of Limits
• Threshold detection
• Ascending (Out trials) increasing stimulus
  intensity
• Descending (In trials) decreasing stimulus
  intensity

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Debriefing

• Normative findings (see Analysis Sheet 1)
• Zero angle most extensive
• Blue-Yellow then Red-Green zone

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Debriefing

• Warning about data interpretation
• Inadequate sample size cant generalize from a
  single subject dont be surprised if your
  subject looks different from the norms
• Lighting conditions more light the better
  cones need bright light to detect colour
• Graph distortion graphing 3D visual field on 2D
  paper just as an atlas is a distorted view of
  the earth

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Thats all she wrote!

• Remember
• Assignment 2 due by beginning of next lab
• Quiz 2 will be next lab
• See Lab Schedule for the date of your next lab.