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Midterm

Midterm #2 (Ch. 5-8) Review A great resource to study the details discussed in Chapters 5, 6, 7, & 8. For the second midterm in the course.

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Department
Psychology
Course
Psychology 1000
Professor
Laura Fazakas- De Hoog
Semester
Fall

Description
Chapter 5Sensation and Perception Sensationthe stimulusdetection process by which our sense organs respond to and translate environmental stimuli into nerve impulses that are sent to the brainPerceptionactive process of organizing the stimulus input and giving it meaningSensory ProcessesStimulus detectionabsolute threshold designated as the lowest intensity at which a stimulus can be detected 50 of the timeSignal detection theoryconcerned with the factors that influence sensory judgments o Decision criterionstandard of how certain a person must be that a stimulus is present before they will say they detect it o Increased rewards for noticing stimuli often results in lower detection thresholds o Increased dangerpunishment for noticing stimuli often raises detection thresholdDifference thresholdsmallest difference between two stimuli that can be perceived 50 of the time just noticeable differencejnd o Webers Lawto perceive a difference between two stimuli one must differ by a constant ratio Value for weights150 therefore if 50 lbs is lifted increased weight will only be detected at 51 lbsSmaller fractionhigher sensitivityDoesnt apply to extremely high or low stimulation intensitiesSensory adaptationthe diminishing sensitivity to an unchanging stimulus o Perception of stimuli will decrease if constantly presentThe Sensory SystemsVisionThe Human Eye o Light enters eye through cornea transparent protective structure o Pupiladjustable opening that dilates or constricts to control amount of light entering o Iriscontrols the pupil o Lenselastic structure that becomes thinner to focus on distant objects and thicker to focus on nearby objectsImage flipped and reversed onto retinaAbility to see clearly depends on lens ability to focus image onto retinaMyopia nearsightednesslens focuses image in front of retina Hyperopia farsightednesslens focuses image behind retina o Retinamultilayered tissue at rear of eyeballPhotoreceptors Rods and Cones o Retina covered in lightsensitive receptor cells o Rodsblack and white receptorsFunction best in dim light o Conescolor receptorsFunction best in bright light o In humans rods are everywhere except fovea direct center of retinaCones decrease in concentration distant from the fovea o Rods and cones send message to brain via two additional layers of cellsBipolar cells have synaptic connections with rods and conesBipolar cells synapse with ganglion cells whose axons form into optic nerve o Cones in the fovea each have private line to a single bipolar cell unlike others which have many rodscones for each bipolar cellVisual acuity ability to see fine detail increases with image directly on fovea o Blind spot exists at point where ganglion cells exit to form optic nerveTransductionprocess where characteristics of a stimulus are converted into nerve impulses o Rods and cones accomplish transduction through photopigments o Absorption of light be photopigments increases release of neurotransmittersBrightness Vision and Dark Adaptation o Dark adaptationthe progressive improvement in brightness sensitivity that occurs over time in low illuminationCones adapt completely in 10 minutesRods continue adapting for 30 minutes allowing extreme sensitivity to lightColor vision o Trichromatic theorythree types of color receptors in retina blue green redAll colors produced by combination of wavelengths between these three colorsFlaws in theoryYellow produced by red and green yet people with redgreen color blindness can see yellowColor afterimage image in different color appears after stimulus shown for a while then withdrawn o Opponentprocess theorythree color receptors each responding to two different wavelengths redgreen blueyellow blackwhiteExplains color afterimage issue o Dual processes in color transductionModern dualprocess theory combines both theories to account for color transduction processCones contain one of three different photopigments that are sensitive to blue green and redDifferent combinations of intensities will produce different colorsOpponent processes occur but not in conesGanglion cells respond in opponentprocess by altering firing rate o Colordeficient visionDichromatcolor blind to only one system redgreen or yellowblueMonochromatcompletely colorblind only sees blackwhiteAnalysis and Reconstruction of Visual Scenes o Feature detectorsOptic nerve sends nerve impulses to brain thalamus then primary visual cortexGroups of neurons in the cortex are organized to receive and integrate sensory nerve impulses from specific regions of retinaFeature detector cells fire selectively to stimuli that have specific characteristicsCertain cells fire when horizontal line present others when other angles presentParallel processingdifferent cells analyze stimuli and construct unified image of its properties o Visual association processesInformation analyzed and reconstructed in primary visual cortex is routed to other regions known as visual association cortexAuditionFrequencynumber of sound waves or cycles per second Hzone cycle per secondAmplitudevertical size of the sound waves decibelsdbTransduction system of ear is made up of bones membranes and tubes o Sound waves vibrate eardrum which vibrates three bones hammer anvil and stirrupAmplify sound waves more than thirty times o Cochleacoiled snail shaped tube that contain basilar membrane sheet of tissue o Organ of Corti rests on the basilar membraneHas thousands of tiny hair cells that are actual sound receptorsSound waves cause waves in liquid which bend hairs causing release of neurotransmitters
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