Psych 105-3 - WEEK 3 Notes Development of Perception...

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Unformatted text preview: WEEK 3 Notes 8/15/11 Development of Perception Perception o Preferential looking technique DV: looking time o Infants look longer at the bullseye than at horizontal lines o Show infants checkerboard (lots of contrast) o Infants prefer something > nothing (enjoy contrast) o Prefer complex stimuli Visual Acuity: Spatial sensitivity o Adults use snellen chart (letters of different sizes) o Infants- preferential looking technique (PLT) Patch of gray on one side Alternating dark and light bars; one with large spaces, one with small spaces (keep making spaces finer) Infant will look at alternating bars more than the patch of gray Most infants are functionally blind at birth (poor visual acuity) • 20/200- 20/300 1 year: near adult VA 5years- mature VA REASON: retina is underdeveloped, WHY? • Fewer # of cones- they cannot see details, bad resolution • Fewer photo pigments (poor sensitivity) o Variation in spatial sensitivity with age Y axis- contrast X axis- width of bars Contrast sensitivity function • Look at picture of bars • Resolution limit on right side o At birth babies can only detect patches of color o 8months~ vision is more clear o LIMITATIONS: Doesn’t take preference into consideration • Baby may look at gray patch because it prefers the gray patch Problem with PLT o If the infant fails to show a preference it could be because: They don’t detect a difference They detect a difference, but have no preference Habituation o Y axis: looking itme o X axis: trials o The more times they seem the power, the shorter the looking time should be o Habituation phase is showing an infant the same pattern until they get tired of it o When to stop the habituation phase? Fixed number of trials Set of criterion • Continue showing same stimuli until the sum of the last 3 consecutive trials is exactly half of the sum of the first 3 trials Size Constancy o The visual system factors in distance o See constancy (Slater, et. all, 1990) Habituation with newborn • Fixed number of familiarization trials (6) o If they have size constancy Infants realize the images are the same (habituation) o No size constancy= infant sees a new image everytime the size of the image changes • Test trials o No size constancy- never would have habituated; equal looking o IF they have size constancy- habituate; look more at new than at the old o RESULT: Believe that infants HAVE size constancy Integrate proximal image and depth cues...
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This note was uploaded on 09/03/2011 for the course PSYCH PSY 105 taught by Professor Cohen during the Spring '11 term at UCSB.

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Psych 105-3 - WEEK 3 Notes Development of Perception...

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