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Unformatted text preview: HDE 101 Study Guide I. Perceptual Development (Ch. 7) A.) General sequence of development 1.) General Concepts :-Sensory receptors/sense organs-General pattern of transmission -sense of organs Thalamus Cortical areas-Organizational principle-Topographical mapping-Receptors translate stimuli into electrical signals 2.) Organization of sensory systems:- Peripheral before central-Relatively more developed peripherally than centrally earlier in development -Infants are not blind or deaf at birth-By 4 to 6 months of age, vision and hearing are close to adultlike 3.) Why interest in infant Visual Perception?- Natural curiosity about how sophisticated devices can come to be.- Current experimental procedures to study cognitive abilities involve visual stimulation- Early eye abnormalities can cause seemingly permanent deficits-Development of new techniques for measuring visual capabilities. - Brain devotes more space to vision than to all other sense combined.-We know more about vision than any other mental ability. 4.) Vision at Birth:-Vision still primitive-Why?- Maximizes the role of experience-Permits just the right amount of visual experience- No visual stimulation in the womb-Infants can see about 8-12 inches in front of them-Have acuity of about 20/660 about 30 times poorer than 20/20 vision 5.) Development in the Visual System:-Primary Visual Pathway: Overview of Information Flow:-From the optic chiasm information is transmitted along the optic radiation to the Lateral Geniculate Nucleus (LGN) of the thalamus (LGN) is a subcortical relay nucleus). -Finally, information is transmitted from LGN to the Primary Visual Cortex (PVC, or Striate Cortex). 6.) Components of the Visual System: a.) Lens- i.) Fully developed at birth ii.) Functional: Accommodation -ability to shift focus to different distances-visual system can only focus on one distance at a time-to adjust to seeing at a new distance , the shape of the lens changes-accomplished by expanding and contracting the muscles around the eye to change the thickness of the lens-infants do not see distance as well as adults-originally thought to be because of immature lens-newer studies show that they can accommodate, but they are slow and inaccurate until after about 2 months of age. b.) Retina i.) Composed of photoreceptors: rods and cones ii.) Many more rods than cones (most cones are in fovea ) iii.) Fovea is less mature than periphery iv.) Cones are shorter and fatter in infants than adults until 11 months v.) Infants have better peripheral than foveal vision c.) Optic Nerve- i.) Thinner and shorter in infants , not fully myelinated ii.) Myelination complete by about 3 months iii.) Peripheral-central progression iv.) Begins at 24 weeks gestation -Length myelinated by 1 month postnatal-Dramatic increase between 1 and 3 months d.) Visual (Striate) Cortex- i.) Full complement of neurons and dendrites are short at birth, few project- Dendrite spines proliferate after birth , peak at about 6 months...
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- Summer '08