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Ashley Waggoner Denton

CH5 – SENSATION How do We Sense Our Worlds  SENSATION – sense organ’s response to external stimuli & responses  Sensation to Perception: transmitted to brain o 1. Stimulus – environmental features o elementary experience, w/o perceptual experiences o 2. Sensation – detect stimulus o ex. light, air vibrations, odor not what object o 3. Sensory coding – stimulus transduced  PERCEPTION – brain’s further process of detected signals o 4. Perception – brain processes neural signal o conscious internal representation of stimuli, construct info from sensation  Sensory coding – sensory organ’s translation stimuli: physical properties  neural impulses o TRANSDUCTION – sensory receptors pass produce neural impulses when receive physical or chemical stimulation  Sensory receptors – Specialized neurons in sense organs  connection neurons pass neural impulses to brain  only sensory organ’s neurons directly respond w/ stimuli, brain respond to other neurons’ input  Psychophysics – psychological experiences of physical stimuli o different physical features has different neural impulse patterns o assess physical energy req. sense organ detect stimuli  light, odors, physical contact unique patterns  Sensory Thresholds:  b/c brain can’t process raw stimuli o Absolute Threshold – min. stimulation intensity req. for sensation o Reception: most sensory  thalamus, then thalamus  cortex  i.e. stimulus intensity detected above chance  cortex = information interpreted as smell, sound, touch  ex. Sound = faintest sound detectable 50% time  Qualitative information – diff. sensory receptors respond to o Difference Threshold – just notable diff. btwn 2 stimuli qualitatively different stimuli –ex. tuba vs. flute, red vs. green  i.e. min. changed req. to detect difference  Quantitative information – same sensory receptor, different  Weber’s law – just noticeable difference btwn 2 stimuli based firing speed –ex. higher freq. w/ brighter light, louder sound proportional to original stimuli, not constant  Coarse decoding – sensory qualities coded w/ few diff. receptor,  SIGNAL DETECTION THEORY – faint stimulus detection req. judgment = each = broad range stimuli  combination = diff. quality subject interpretation, not objective o theory of perception, based on thresholds Response: YES Response: no Stimulus: ON Hit Miss Stimulus: OFF False Alarm Correct Reject o Response Bias – participant’s tendency report T/F detection  Sensory Adaption – decrease sensitivity to constant level of stimulation o response diminish over time, agree w/ mind is adaptive o strong response when continuous stimulus stops GUSTATION – sense of taste  Stimuli: chemical substances, molecules dissolve in saliva on tongue o Biological  supertaster = highly sensitive, extreme dislike bitter  TASTE BUDS – sensory receptors, taste cells in buds transduce taste o Cultural influence  begin w/ womb & breast feeding o average 500 – 10 000 per person;  mother’s food preference pass down to newborn o 5 basic qualities: sweet, sour, salty, bitter, umami *savory”  Pathways to the Brain: along cranial nerve  sensation associated differences o taste preference experience w/i brain  mix w/ texture, smell OLFACTION – The sense of smell  Stimuli: molecules dissolved in fluid on mucous membranes in the noes o prefrontal cortex process smell pleasant/aversive; smell intensity  ORFATORY EPITHELIUM – thin layer of tissue, embedded w/ receptors another region = amygdala o Odorants – chemical particles, pass into nose to nasal cavity  emotion, memory also prefrontal cortex, related w/ smell o thousands receptors ID’d, correspond w/ diff. chemical group  Receptors: olfactory neurons’ sensitive ends in mucous membranes  encoding nature unclear, 1 receptor type detect 1 specific odor, o When receptors in the nose respond to chemicals. or 1 odor stimulate unique receptor combination  Pathways to the brain: along olfactory nerve  OFLACTORY BULB – brain center for smell, receptors transmit info. to it, below prefrontal cortex HAPTIC SENSE – The sense of touch  Stimuli: tactile simulation – contact w/ skin  in all tissues: skin, muscles, membranes, bones, joints, organs  Receptors: sensitive ends of touch neurons in skin o Fast Fibers – for sharp immediate pain o Temperature/pressure = sensory exterior  Activated by extremes physical pressure/temp. o Sensing temperature – separate hot/cold receptors  causes recoil, protective purpose  can trigger both a/ intense stimuli o Slow Fibers – for chronic, dull, steady pain o Nerve fibers at base of hair follicles also receptors  activated by chemical changes in tissues when skin damaged  prevents us using affect body parts, recuperative  respond w/ movement in hair o Other pressure receptors = capsules in skin, respond continued vibration, sudden movement, steady pressure o various signal integration w/ higher-level mental process produce haptic experiences  ex. stroking pressure points = tickling sensation  Pathways to the Brain: trigeminal nerve (touch above neck), spinal nerves (elsewhere)  Gate Control Theory – brain regulates pain experiences, suppress/reduce o pain signals transmitted by small-diameter nerve fibers, block-able at spinal cord w/ large sensory nerve fibers  pain experience = pain receptors activate & spinal cord’s neutral “gate” allow signals  mental process (worry of painful stimuli) opens gates  pain process area also stress, fear, anxiety = sensory & emotional response o Females lower pain threshold  sex role theory: consistent pain, men less likely to admit  contrary: females greater pupil dilation, more complex pain management system  pregnancy  females: lower threshold w/ higher estrogen levels o pain treatment: brain-based vs. traditional  ex. learned techniques, alter brain activity, reduce pain  ex. traditional medicinal options: morphine  Pain Receptors o pain = warning system, stop continuing activities o pain nerve fibers (2 types) thinner than temperature/pressure: ADUITION – the sense of sound perception  Stimuli: SOUND WAVES –changing air pressure pattern through time  cochlea: fluid-filled tube, curls, snake-like shape, inner ear o wave’s amplitude = loudness (higher = louder) o basilar membrane – cochlea center, connected w/ cochlea’s hair o wave’s frequent = pitch (higher Hz = higher pitch) cells  Outer Ear  auditory canal to eardrum o hair cells = primary auditory receptors  EARDRUM – thin membrane, across canal, marks middle ear beginnings  bends w/ pressure waves, neutrons fire in basilar membrane o waves vibrate eardrum, transferred to ossicles bones (hammer, nail,  Localization  audition sensory receptors doesn’t code event locations stirrup) o brain integrates sound travel time & intensity bt
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