Chapter 7 Notes - Psych 2220

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Psychology 2220A/B
Jennifer Hoshooley

Chapter 7 – Mechanisms of Perception: Hearing, Touch, Spell, Taste  One guides actions w/out conscious - Sound waves: patterns of air flow created by vibrating objects &Attention awareness The Ear - Exteroceptive sensory systems: include visual (ch. 6),  One guides actions by engaging our auditory, somatosensory olfactory, gustatory systems - Waves enter auditory canal of ear and cause tympanic conscious awareness membrane (eardrum) to vibrate Principles of Sensory System Organization - Sensory systems characterized by the division of labor - Sets bones of middle ear, the ossicles (malleus, incus, stapes) - Neocortex: 6 cell layered outermost covering of the surface of in motion which vibrates oval window the brain o Sensory info processed by multiple specialized areas @ multiple levels and interconnected by multiple parallel pathways - Oval window transfers vibrations to fluid of cochlea (snail - Areas of neocortex involved in processing sensory info divided shaped thing) into 3 types: - How do the bits of analyzed info come together to give rise to - Sound recorded in form of waves o Primary: receive input mainly from thalamic relay our integrated perceptions? nuclei o The Binding Problem - **For ea. term related to a physical dimension of the sound stimulus there is a corresponding perceptual dimension o Secondary: receives input mainly from primary & secondary cortex w/in sensory system  Not one specific area in brain where all analyzed info comes back together to be o Amplitude: experience of loudness bound into integrated perception o Association: receives input from more than one o Frequency: experience of pitch sensory system, usually from secondary cortex  Awareness of corticofugal (nerve fibre - 3 major principles apply to processing of sensory info both passing away from cerebral cortex) o Complexity: experience of timbre pathways passing though area of w/in and w/out sensory cortices - Fluid in cochlea set in motion by vibration of oval window sensory analysis and allow higher areas o Hierarchical Organization: move through levels of of processing to influence lower levels of sensory system, neurons respond optimally to processing and have influence on o Auditory receptor organ = cochlea’s internal perception (top-down) membrane, The Organ of Corti stimuli of greater complexity and specificity o Organ of Corti composed of 2 membranes  Higher the level of damage to system, TheAuditory System more specific and complex the deficit - Sounds – vibrations of air molecules that stimulate the  Basilar membrane auditory system  Sensation: process of detecting presence of stimuli  Tectorial membrane o Humans? b/w 20-20000 Hz (cycle per sec) o Stimulation of hair cells triggers action potentials in  Perception: higher-order process of - Pure tones (sine wave vibrations) exist only in lab settings auditory nerve integrating, recognizing and interpreting complete patterns of sensations - FourierAnalysis: mathematical procedure for breaking down o Cochlea shows tonotopic organization complex waves into component sine waves o Functional Segregation: ea. cortical level of  Diff frequencies produce maximum sensory system is divided into diff areas that - Pitch of a sound is related to fundamental frequency (highest analyze sensory info in diff ways stimulation of hair cells @ diff point frequency of which the various component frequencies of a along basilar membrane sound are multiples); o Parallel Processing: diff aspects of stimulus Getting Sound from Ear to Primary Auditory Cortex analyzed at the same time o Pitch of a complex sound may not be directly related to frequency of any of the sound’s - Major structures involved in processing sound: components - Cochlear Nerve: branch of cranial nerve VIII & transmits - Cochlear implants used to help some people who have nerve  Info ascends through dorsal columns auditory info from cochlea to brain deafness then through medial-lemniscus - Cochlear Nuclei: group of nuclei in medulla that receive Somatosensation  Info reaches relay thalamus & input/info from cochlea - Somatosensory system comprised of 3 separate (but distributed to primary somatosensory cortex (SI) & to secondary - Superior Olivary Complex: group of nuclei in medulla interacting) systems somatosensory cortex (SII) associated w/ auditory functions incl. Localization of sound o Exteroceptive system: senses stimuli external to o Anterolateral system the body - Lateral Lemniscus: band of fibers running through the medulla and pons and carry fibers of auditory system  Pain and temp o Proprioceptive system: monitors position of body - Sound localization mediated by lateral and medial superior o Interoceptive system: receive info about internal  Info ascends through 3 diff tracts: olives ... both structures react to differences in what is heard by the two ears condition of body • Spinothalamic o Medial Superior Olives: respond o arrival time Skin Receptors (Cutaneous) • Spinoreticular differences o Slow and fast adapting o Lateral Superior Olives: respond to differences in • Spinotectal amplitude o We respond to change; no change = no sensation - Free Nerve Endings – convey info about temp & pain  Info reaches relay thalamus and is - Both structures send projections to superior and inferior distributed to primary somatosensory colliculi which further analyze location of sensory input cortex (SI) and to secondary sources in space - Pacinian Corpuscles – large, deep, onion-like; adapt rapidly & somatosensory cortex (SII) respond to sudden displacements of the skin - Signals are headed towards: - Primary Somatosensory Cortex (SI) - Merkel’s Disks – adapt slowly & respond to gradual skin o AnteriorAuditory Pathway (to prefrontal cortex & indentation o Postcentral gyrus involved in sound identification) OR Posterior - Ruffini Endings – adapt slowly & respond to gradual skin Auditory Pathway (posterior parietal cortex and is o Somatotypically organized (according to layout of involved in sound localization) stretch the body) = homunculus Hearing Impairments - Stereognosis: identification of objects by touch  Distorted such that sensitive areas of
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