Sensation and Perception - Chapter 3

Sensation and Perception - Chapter 3 - Chapter 3- Sensation...

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Chapter 3- Sensation and Perception Sensation- input about the physical world provided by our sensory receptors Perception- the process through which we select, organize and interpret input about sensory receptors. Sensation Sensory receptors located in our eyes, ears, nose, tongue and elsewhere are responsible for the coding task. The sights, sounds and smells which we experience are converted into neural signals and are transmitted to the brain via sensory nerves. This is known as transduction. Sensory Thresholds Hallucinations are spontaneous internal patterns of neural activities generated by the visual system in the face if diminished external sensory stimulation. Absolute thresholds- the smallest amount of a stimulus we can detect 50 percent of the time. One complication with absolute thresholds is the variation in sensitivity to stimulus from moment to moment due to ones body staying at optimum levels otherwise known as homeostasis. Signal Detection Theory- a theory suggesting that there are no absolute thresholds for sensations. Rather, section of the stimuli depends on their physical energy and on internal factors such as the relative costs and benefits associated with the detecting their presence. Ex. Doctor spending money Difference thresholds- the amount of change in a threshold un a stimulus required before a person can detect the shift. Ex. Tasting something, then adding salt and tasting the difference. Just noticeable difference - the smallest amount of change in a physical stimulus necessary for an individual to notice a difference in the intensity of a stimulus. Ex. When music is being played low turning it up a little is noticeable while when it is really loud turning it down slightly is not noticed greatly. Subliminal Threshold - the presumed ability to perceive a stimulus that is below the threshold for conscious experience. Ex. Flashing advertisements for a split second. Sensory Adaptation Reduced sensitivity to unchanging stimuli over time. Ex. Cold water feels good after a while. Vision The Eye: It’s basic structure Light rays first pass through the thin transparent layer called the cornea and enter the pupil, the round opening just behind the cornea.(the less light present the wider the pupil opens). These adjustments are conducted by the iris, the colour part of the eye
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which contracts or expands the pupil. The light then passes through the lens, a clear structure whose shapes adjust to the permit us to focus on a object. Light rays leave the lens and are projected to the retina at the back of the eyeball. Usually the image to the retina is upside down but the brain interprets the information as upright. Cones- sensory receptors in the eye that play a crucial role in sensations of colour.
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This note was uploaded on 12/20/2009 for the course PSYCH 1000 taught by Professor Atkinson during the Spring '09 term at UWO.

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Sensation and Perception - Chapter 3 - Chapter 3- Sensation...

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