Human Sensation&Percept PSYC 3041
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Psychology 30416014 Spring 2012 OLFACTION SMELL Overview Smell phenomena Anatomy and physiology Pathway Co 39 Pheromones F avor 1 Functions and Facts Distal sense 0 Bene cial in detection of predator prey mate chocolate sundae Longterm o Stimulus could have been there hours days weeks before Biologically motivated Most odors are organic in origin 0 Many odors come from animals and plants 0 Food seeking o Helps locate identify and assess food before eating it 2 Odor Quality 0 Approximately 10000 different odors can be discrimina Chemicals inthe air lead to odors Must be volatile Molecular weight 15300 0 Must be soluble I In both water amp lipids 0 Usually or anic m unumwnmn 5112212quotwa a1 mum 7 mm Dummy o a Unnmm Warmly Mucm oner mm mums mmmmm mums ovmw mm ma mm 45 u u uumn mumm mm Huml H IM My my um pm Mr myullrmm mun1 g Elemental substances are usually nonodorous Classi cation schemes try to de ne core or primary odors eg Henning39 Amoore 1965 O No scheme has proved satisfactory lof7 Psychology 30416014 Spring 2012 3 Anatomy and Physiology Chemicals inhaled Dissolved in olfactory epithelium Receptors Direct links to brain a Olfactory Epithelium i Located on top surface roof of the nasal caVity ii Cribriform plate 1 Porous bone Oltanorybulh 2 Separates sinus from brain I 3 Cribriform latin for seive iii Mucosa contains olfactory receptor cells 1 Cilia on bottom sinus end 2 Nerve fibers on top end which lead straight to the brain olfactory bulb iV Olfactory bulb 1 Projection of the brain just on top of cribriform 0mm p ate receptor Zof7 Psychology 30416014 Spring 2012 camquot mnlsculs ccepmrs Receptors a D33 M amp w v Olfactory cells With cilia spread through mucosa vi Chem39 als in the air absorbed into mucosa vii Receptor sites on the cilia correspond to different It amp l M molecular shapes M viii lock and key arrangement similar to taste quot E E 1 But thousands of different receptor types Q9 amp Receptors respond in different amount to many chemicals 7 not speci c 0 limit 1amp1 w 1 b Organization of receptor cells in the mucosa g 1 DE E i zones in mucosa 1 Each particular type of receptor is found in Only one is 739 A hypmhaivm when 71 coding 0 album mtmmonan m Zone Men odemnl molecule mach yo diNemnl wmbmuuum of temp wa e 391 lot mallxul A 7 v a r mulecnlcs are lulwn In B a Randomly spread throughout the zone unique will Elwynumquot figmen particulmisdummm b Multiple receptor types in each zone Stit l39 filz i 5 Hum 1 5m and Mquot a aquot ii Axons from one zone all go to same area of olfactory bulb c Olfactory bulb i Brain projection 1 Receiving point for receptor nerve bers iii Inputs to a given glomerulus come from a single type of receptor and from a single zone on the mucosa iv About 10002000 glomeruli V one reduction Which leads to sensitivity like rods in retina cmw lympch reuron VORN cuacmrymuccsa 7 J 51 3977 39 r V S Pathway 201 1amp9 g y 1 O Zune 2 J i y H l V 39 v1 Olfactorybulb M 3 uf V VV V Ollacmry u 1 Brain pIOJeCtIOH m ght31m nl actoryconex quot vu nmary olfactory bquot quot aquot cortex piriform Temporal viii Secondary m9 olfactory corte 39 I mm 1x Amygdala minimm 1 Deep in cortex Figure 147 Ilw umlcrmlc u lm hmfn shown the nauml palumxlnr Mlul linn Ou vw 1111 My vlw tempnml Iuhu hm mu Imamd m mmse m ulZmzm mm wmm l um v a 3 of 7 Rubin 1089 Psychology 30416014 Spring 2012 2 Related to emotions limbic system 4 Neural coding a Intensity i Many receptor cells ii Therefore more chemical means more intense smell b Quality i Pattern of activit ii Set of responses across a range of cells and a range ofregions ofmucosa DH v 111 Some bersreceptors are quite spec1 c A 41 iv Others have broad responses many odors CH2 oquot CHs V o v v Not clear how nearly identical chemicals can Bolh pmeapula smell very different nearly same smells can have very m different chemicals Figure 143 v H 11 mm m my Mac mi mm 111111111111 1111 m It 39mu lu Nwr u Kimm m1 jun urnw Thresholds rml 1m vim1 1111 c Detection i On a cellbycell basis we re as good as could be expected 1 We can detect one molecule 11 We can detect 1 molecule of mercaptan in 50 trillion molecules of air 1 Used as an odorant in natural gas Why iii Dogs have 200 times more receptor cells and each one has more cilia d Gender i Males and females have different thresholds 1 Depends on the odor andthe state of the smeller a Eg menstrual cycle mating season age 2 Eg exaltolide 7 a base used in perfumes Women particularly at peak levels of estrogen can detect 1000 times better thanmen and prepostmenstrual women b Seems to mimic a pheromone more later Age i Detection declines With age ii A problem for detecting bad food leaking gas personal hygiene diet iii Safety and health issues 4of7 Psychology 30416014 1 Such as f Adaptation i Prolonged exposure reduces awareness of a smell 1 Eg baking 7 you don t realize how good those cookies smell39 2 Eg personal odor 7 you don t realize how unlike those fresh cookies M smell 5 Odor and memory a Can serve as a very potent and longlasting memory cue b Episodic odor i Associated With real events ii Can trigger emotional and even visceral reactions iii O en related to food aversions unpleasant places or experiences 1 Eg hospital smell barber smell 2 nothing like the smell of napalm in the morning 7 Sof7 Spring 2012 in mm onurs mammary 9mm Labmaiorv cums Cmmcl mmgmrmusvsw V l r a stow mus lag M Mme mm 5mm Hgm 557 rganRas swepa il wen Psychology 30416014 6 Spring 2012 Pheromones i Chemical communication ii Exit the body to signal other beings b Releaser pheromones i Produce an immediate amp direct effect 1 Eg attracts male to female in heat c Primer pheromones i Produce or change a longlasting state 1 Eg smells from both men and other women can change menstrual cycles d Marker pheromones i Mark atrail indicate a path or status of a resource 1 Eg ants mark trail to food until food is gone e Alarm pheromones i Certain states signaled by chemical signature 1 Eg stress in rats is smelled by other rats 2 Eg animals can smell fear in other animals Common chemical sense a Free nerve endings in the mucosal membranes nose mouth eyes respiratory tract i Branches of the trigeminal nerve ii Detect irritants 1 E g pepper ammonia mustard Pepper 7 capsaicin active ingredient 1 Why spray pepper in the face amp eyes 2 Frequent use or exposure can desensitize by destroying nerve endings iv Smelling salts v wasabi head b Brain freeze i Combination of free nerve endings and direct stimulation of pain receptors ii Goes straight to olfactory bulb iii Why does rubbing the forehead help iii 6of7 Introduction to the Physiology of Perception Chapter 2 The Brain The Mind s Computer 0 Brief History of the Physiological Approach 0 Early Hypotheses About the Seat of the Mind I Aristotle heart gt mind amp soul I Galen mind amp soul determined by quotspiritsquot from ventricles o Ventricles cavities in center of brain I Descartes soul comes from pineal gland 0 Pineal Gland located over ventricles o The Brain As the Seat of the Mind I Willis brain is responsible for mental functioning o Signals Traveling in Neurons I ReticularTheog nervous system consists of large network of fused nerve cells Neuron Theom nervous system consists of distinct elements or cells Golgi developed technique to stain random individual cells Johannes Mueller 0 Doctrine of Speci c Nerve Energies our perceptions depend on quotnerve energies reaching the brain 0 Specific quality we experience depends on which nerves are stimulated 0 Recording From Neurons I Adrian recorded electrical signals from single sensory neurons 0 Basic Structure of the Brain 0 Cerebral Cortex 2mmthick layer that covers the surface of the brain and contains the machinery for perception language memory and thinking I Modular Organization specific functions are served by specific areas 0 Prima Receiving Areas first areas in cerebral cortex to receive signals initiated by each sense s receptors I Occipital Lobe primary area for vision I Temporal Lobe primary area for hearing I Parietal Lobe area for skin senses touch temperature pain 0 Frontal Lobe receives signals from all of the senses and helps coordinate information Neurons Cells That Create and Transmit Electrical Signals 0 Structure of Neurons 0 Cell Body contains mechanisms to keep the cell alive 0 Dendrites branch out from the cell body to receive electrical signals from other neurons 0 Axon Nerve Fiber filled with fluid that conducts electrical signals 0 Receptors specialized to respond to environmental stimuli 0 Recording Electrical Signals in Neurons o m consists of axons that carry signals I Resting Potential difference in charge between inside and outside of the nerve fiber when the fiber is not conducting electrical signals I Action Potential rapid increase in positive charge in a nerve fiber that travels down the fiber 0 Chemical Basis of Action Potentials o Ions molecules that carry an electric charge I Na I K CI 0 Basic Properties of Action Potentials o Propagated Response once the response is triggered it travels all the way down the axon without decreasing in size 0 Refractog Period interval between the time one nerve impulse occurs and the next one can be generated in the axon o Spontaneous Activiy action potentials that occur in the absence of stimuli from the environment 0 Events at the Synapse o Neurotransmitters o ExcitatomTransmitters I Depolarization o InhibitomTransmitters I Hyperpolarization Neural Processing Excitation Inhibition and Interactions Between Neurons 0 Introduction to Receptive Fields 0 Receptive Field area on the receptors that influences the firing rate of the neuron I CenterSurround areas of receptive field are arranged in a center region that responds one way and a surround region that responds in the opposite way 0 CenterSurround quot 39 39 39 between center and surround regions Psychology 30416014 Spring 2012 PAIN PERCEPTION Overview Receptors amp pathways Cognitive aspects Gate control theory Endorphins Summary 1 Phenomenon Samalasansmycunex SH Amevlm magma women 1 mom Multimodal experience involving many sensory systems 0 Touch audition olfaction vision etc Emotional experience as we 0 Melzack 1999 points out the words used to describe pain are highly emotional I Annoying frightful sickening 39 1 0 Both annoying biologically useful mun1 m Wombmel rm 2 Receptors amp Pathway a Nocioceptors Free nerve endings b Spinothalamic pathway 0 low small bers ynapse inthe spinal cord 0 Cross over to opposite side of brain from receptor at level of spinal cord contralateral S S c Brain regions Multiple regions demonstrates multimodal experience Emotional aspects are associated with ACC o Postfrontal lobotomy patients feel pain but it is not as emotionally disturbing as it was before PH mm WWW hm mam mm mm m 5 a M w and surgery BUT emcmanal mnpunems cl pain Hum Dorsal Haws 010m bran Aclivulmnolvhe Hmar sumavomnsor mrlexcwcledmred igure 725 m a ecr d analgesia indicating Ilml llus raglan responded in the sensory 1 of5 nensalpuiu mun m Bn much as saw when a mum stimulus was presumed u a c an From Rumvll v 11 Duncan G H Mm D D Camel a and Bux nv neH M c Science 197 277 MB WV Psychology 30416014 Spring 2012 O Thalamus Hypothalamus Limbic system Also insula and anterior cingulated cortex ACC The Pain Matrix i Thalamus ii Hypothalamus iii Limbic system iv Also lnsula and anterior cingulated cortex ACC v Notes The Pain Matrix 3 Cognitive Aspects of Pain a Expectation NEDEIESE Knowing What is happening reduces pain so 7 0 Surgery patients Who are told What the procedure involves felt less pain 50 Westerners Placebos o en effective 0 But anticipating the pain can make it worse gt 40 Eg torture based on the threat 20 i b Shifting attention Threshold Famt lam Extreme 3 VR game used to distract burnpatrents Reponed penance p m o Hoffman et a1 2000 H um 37 Experienced less pain Rm 0 nu um 1an Im v mm mMHHMHL which Note Nintendo was not as effective Why mumm 1mInevidelunlelarlmgu hnck nm Hmmm or my Wme whit51 um um vaalew whim but mm me 4 Jaime subch Wk much lugnquot lyrek quotmmA Hzmu mm rm min or mlmme prim c Distraction Males looking at pictures that had been rated as positive sports attractive females experienced less pain ice emersion 2of5 Psychology 30416014 Spring 2012 0 negative images resulted in more pain de Wied amp Verbaten 2001 d Individual differences shocks applied to people from different cultures 0 Weste e alese o Nepalese reported less pain that Western 0 Clark amp Clark 1990 0 Possible explanations Track athletes report less pain than nonathletes Hall amp Davies 1991 0 Why e Locus of Control nescagable pain shocks to rats ledto analgesia higher shock tolerance Pain that the rat could aVaIddid not lead to analgesia Note adult children of alcoholics have higher than average tolerance for pain Not clear iflearned or genetic Either way it could be adaptive if pain either frequent or inescapable or both is part of that person s likely experience I Injury disease abuse accidents or emotional pain Just food for thought See work by Robert Pihl OO 00 4 Gate Control Theory a Basics Melzak amp Wall 1965 1988 Large bers carry nonpain touch info from cutaneous receptors to brain Small bers carry temperature amp pain sensations lfthe less powerful pain signal comes along and no other signal is owing through the pipes the pain signal makes it through 3of5 Psychology 30416014 Spring 2012 0 Note there is a topdown element to explain cognitive and emotional factors Feeds back into large ber touch loop which can either increase or decrease perception of pain b Biological Circuit my me i Substantia gelatinosa ii Transmission or Tcells in dorsal horn of spinal cord Neural circuit containing these cells works as described in L e eory Substantia gelatinosa and 7 cells work as a gate Tcells transmit pain up spinal cord 1 1 Central control necessary to explain how we can cognitively sil in uence paln fi quotquot1 5 quotl iv Stimulusproduced analgesia SPA 1 Rats with brain stimulation can undergo surgery without anesthesia 4of5 Psychology 30416014 b lof6 Spring 2012 FUNDAMENTAL AUDITORY FUNCTIONS Loudness a Human hearing is amazing i In optimal conditions the best human hearing sensitivity is equivalent to hearing the random movement of molecules ii Sensitivity is frequencydependent Physical attribute of sound is intensity 10000 Manned spacecraft launch 5000 from 150 feet Perceptual attribute is loudness 1000 39 Sones Loudness sones at 0 Unit of measure used to describe subjective loudness of sounds 5 of differing intensity con Quiet room 39 jRustling of leaves l sone loudness of 1000 Hz tone at 40 dB SPL t L 1 1 I t l 1 1 I l l t x I L J1l 0 20 40 60 80 100 120 140 160 180 200 Sound intensity dB SPL 1 figure 1 3 2 Relationship between intensity level decibels and loudness sones Note that in this function a 10dB increase in the intensity scale increases loudness by a factor of 2 Loudness and mtensny are scaled logarithmi cally Source From Lindsay amp Norman 1977 p 161 Reprinted by permission of the publisher of sones perceived loudness doubles every 10 dB of intensity Compare 6 dB intensity means doubling intensity and 10 dB intensity means tripling intensity i So as you triple intensity you only double the perceived loudness Frequency dependence of loudness Due to the mechanics of the basilar membrane the arrangement and number of hair cells and the auditory pathway including cortical areas perception of loudness differs for sounds of different frequencies Can see this in threshold plots Psychology 30416014 Spring 2012 c Equalloudness contours Feelin Loudness g 129 1 level 0 00 Sound pressure level dB from 00002 dynecmz 720 100 500 1000 5000 10000 Frequency Hz figure 1 3 3 Equalloudness contours The bottom curve 0 phons shows the absolute sensitivity of the ear as a function of frequency Tones with intensity and frequency values that lie below the O phon curve are not audible Source Revised from H Fletcher and W A Munson Loudness its definition measurement and calculation Journal of the Acoustical Society of America 5 1933 pp 82108 Reprinted by permission of the American Institute of Physics 20f6 Psychology 30416014 2 Pitch a Perceived quality of frequency b Discrimination JND i Perceiving changes in frequency Weber fraction i Delta f f 0004 or 04 c Mel scale i Relation between pitch and frequency ii Nonlinear though nearly so in the middle ran e g i 50010000 HZ d Intensity affects pitch perception i Much like frequency affects loudness For low frequency tones i intensity increases perceived pitch decreases iii For high tones Spring 2012 3000 1000 Pitch mels E l Ill 3 Frequency H 5000 lU000 Mn e 1 figure 134 The frequency aitch function Pitch in mels is plotted against frequency in Hz The curve shows how a perceived pitch of a tune vanes with its frequency Observe that pitch increases more rapidly than frequency for tones below 1000 Hz but less rapidly for tones above 100 Hz Frequency is plotted on a logarithmic scale Soucs A ar Stevens kVolkann 1940 1 As intensity increases perceived pitch increases 3of6 Psychology 30416014 Spring 2012 HOW common is it to hear two 3 Multiple frequencies stimulation sound Very close 1n a Many sounds combine to form our acoustic environment frequency In the real world b Beats a Addition of two or more sounds of nearly identical frequencies b Constructive destructive interference leads to periodic increase decrease of amplitude c Heard as beats with frequency of the difference between the sounds i Eg 1000 amp 1002 Hz beat at 2Hz d Examples i Police radar ii Subjective tones iii Missing fundamentals iv multiphonics c Masking a More common for complex sounds to cooccur than two A a u n J nearly 1dent1cal ones a 100 11 dB mask m 0 b One sound can make 1t harder to hear the other 80 8MB masker E 3 60 Asymmetry of frequency effects 1n mask1ng g g 40 E Types of mask1ng g 20 Hearing g threshold 0 l 1 l 39 o 1 o a Slmultaneous mask1ng 3 g g 8 2 T 8 g g 16000 Masker frequency b Forward masking i An earlier sound prevents you from hearing a later sound Frequency of test tone Hz c Backward masking i A later sound prevents you from hearing an earlier one Line busy hypothesis la b C fest l Masker one l Displacement of basilar membrane x l A Distance along basilar membrane gt 4 Direction 0 oval window and stapes 4of6 Psychology 30416014 Spring 2012 4 Threshold shifts a Auditory fatigue b Threshold shift i Temporary ii Permanent 0 Adaptation Sof6 Psychology 30416014 Spring 2012 THE AUDITORY SYSTEM 1 Physical Stimulus Sound Cliche If a tree 0 Frequency HZ falls in the forest 39 anelength m and no one is O Amplitude dB there does it 0 Vibration of an object leads to compressions amp rarefactions of the material make a SOund in the object o This can be transferred and transmitted to other media like air Can describe the sound in terms of physical properties a Frequency Hertz HZ 39 l aaaaaa o n 71 A mm b Wavelength meters m a V N V U c Amplitude decibels dB Pthreshold d Complexity spectrum etc dynescm2 70 Ilpn 2 S131 o Harmonics o What about Ohm s Acoustical Law 6 dB change means a doubling in intensity lof9 Psychology 30416014 Spring 2012 2 Perceptual Attributes Psychological experience of physical attributes a Frequency Pitch b Amplitude Loudness c Complexity richness number of harmonics brightness relative power of ha1monics in different parts of the spectrum iii timbre perceptual signature of the sound DEMO Essentially everything that is not already noted above Spectrai 3 Makes trumpets different from clarinets Components Key point there is a physical stimulus with physical attributes that are essentially incontrovertible there are also perceived psychological descriptions of the stimulus that can change for a number of reasons How is this like time perception Both topdown and bottomup processes at work in affecting perception of sounds 2of9 Psychology 30416014 Spring 2012 3 Anatomy of the Auditory System Outer ear middle ear inner earcochlea auditory nerve auditory pathway auditory cortex mm wmdnw a Outer ear mum neVD i Pinna ears L1an External auditory canal iii Eardrum 7 tympanic membrane vmm b Middle ear i Ossicles malleus incus stapes mm mm 511quot ESSCEV JWWV a Impedance matching gt gt ii Acoustic re ex a Tensor tympani amp stapedius muscles i Not very effective for sirens gunshots etc Very effective for When you speak its very loud inside your head When you talksingproject rm MM to 3of9 Psychology 30416014 c Inner ear cochlea Spring 2012 i Cochlea anatomy only today a 3 Chambers i ii iii Vestibular banal Cochlear duct Tympanic canal b Basilar membrane i c Oval Window As in base as in the bottom i Where the signal comes in from the signal of the stapes 1 Hair cells i Inner 35 OO on the Basilar membrane ii Outer 12000 6 Tectorial membrane i On top f Auditory nerve malarial menmim llnirljui Inn r cell Cilia I Julm Ell GD Vestibular canal l 1 s Ullg l39l Ll fLII l Ressner39s membrane Cochlear duct Region of Tectorial membrane IA Organ of Corti 5 2 Inner hair cell or 439 ll 5 Q 0 3 o I 0 39 40 SCHlH lwnpnm iiilimp nown Bile zu burs l l39lE I liiii39l F Auditory nerve fibers Tunnel of Corti quotBasilar membrane Tympanic canal 4of9 Psychology 30416014 d Auditory neural pathway Sof9 1 Cochlear nerve I 00 E o E a d In 2 In a 50000 afferent axons 39 95 connect to inner cells ii 5 connect to outer Central auditory pathway up to auditory cortex Cochlear nucleus Superior olivary nucleus Inferior colliculus Medial geniculate nucleus Primary auditory cortex Acronym Wemonic SONIC MGquot Spring 2012 1 cortex W Medial gemculate ucleus Inferior colliculus Midbrain 39 Dorsal cochlear cleus Vemral cachiear nucleus Audilary nerve Superior ohvary complex ig u re 7 I 2 me palhwcy or lhe auditory system The moior pathways are m dicmed by heavy arrows Psychology 30416014 Spring 2012 4 Functioning of the cochlea Transduce movement physical energy into nerve ring electrochemical energy 0 Several theories about how the movement of the basilar membrane interacts with the hair cells to leadto a neural signal With only 3500 inner hair cells how can we a Basrc transduction process damning all me complex sounds i RATE frequency matching theory a Frequency of movement of the basilar membrane leads to matching rate of ring i Eg every bend ofahair cell leads to a signal b 100 Hz tone 9 100 hz neural ring c Sometimes only 1 neuron sometimes a volley is required to keep yp the ring frequency d Only works up to about 100 Hz but we hear N20kHz 1 low rate work will get you red ii PLACE theory Traveling wave along basilar membrane a Since the afferent nerve bers from the au 39tory nerve connect to different places along the cochlea perhaps the place that is stimulated most by a sound will lead to ring of speci c nerve bers W b Region of maximum displacement on basilar a quotquotquotquotquot quot39 membrane c So close to one end might be low frequencies and close to the other end might be high frequencies d Region of maximum displacement as W e Traveling wave 2 Hz i Complex signal will decompose into smaller peaks automatic Fourier analysis 3 H 4 f Low frequencies stimulate apex g High frequencies stimulate base of cochlea near stapes mu m lA 39 Bass is not at the base quot g h Works best for high frequencies above N800HZ 1 5 6w Hz A H mm ham slapes mm 60f9 Psychology 30416014 Spring 2012 iii Combination RATE PLACE Theory a Rate works best for low frequencies b Place works best for high frequencies c There is an overlap between about 503000 Hz where both work i Note this is the region central to human sounds b Hair cell functioning i Inner hair cells 0 N3500 Connectedto each other with tip links 39 quot i Synapse onto 48000 95 of bers in cochlear 005 membrane nerve onetomany 1 hair cel Outer hair cells 42000 0 Only connect to N2000 50 of auditory nerve bers manytoone Can change length which results in netuning the frequency response of a region of the cochlea by stiffening of loosening the movement of the basilar membrane feedback mechanism Sets of stereocillia connected by tip links Movement of basilar membrane bends cilia bundles Firing rate depends on force and direction Tip links pull open ion channel i Basically a physical system iii Characteristic frequency of auditory nerve ber 0 Each ber of the auditory nerve res maximally to a particular frequency 0 Basically related to the location along the cochlea basilar membrane that the nerve connec s o tonotopic layout along the basilar membrane i In general terms the ber represents the equency frequencies in the sound 7of9 Psychology 30416014 Spring 2012 5 Auditory Cortex a Pathway recall from previous lecture i Primary Auditory Receiving Area Al Temporal lobe both hemispheres Buried inside lateral sulcus LS Receives input from medial geniculate nucleus of the thalamus Note visual signals synapse in the lateral geniculate nucleus of the thalamus F1957 i Thalamus is a central receiving area for all sensory information ii Core A1 some surrounding cortex belt 111 Parabelt I a Secondary auditory cortex L b Auditory assoc1atron cortex 1 b Tonotopic map in a Each area of cortex corresponds to one characteristic frequency preserving the tonotopic arrangement from the auditory nerve bers c Colurnnar arrangement a Descending down into the brain from the surface ame characteristic frequency but respond to different aspects of the sound i Eg location in space d Plasticity of perception a Area ofthe cortex ofneurons can change With differential usage b More usage gt more neurons being recruited 1 Eg monkey trained on 2500 Hz tone had a large region of auditory cortex devoted to 24 kHz sounds ii Musicians have larger auditory processing area See next page 80f9 Psychology 30416014 Spring 2012 PSYCHOLOGY 30416014 SENSATION AND PERCEPTION Class Notes as of February 21 2012 Introduction History amp Philosophy Syllabus Introduction Why Study History 0 History of a topic does not equal the topic 0 Teaches us at least three things 0 Questions How people view the world and questions they asked about it 0 Methods How people tried to answer these questions 0 Answers Results of those studies conclusions they came to The Problem of Knowledge How can we specify what is knowable without implicitly claiming to know it o How can we sincerely claim to search for what we have not identi ed as knowable or ndable o How in the end can we ever be sure we know anything The Greeks philosophical giants 2 0 Roots of all of this are in early Greece and Ionia o Vast amounts of philosophical records preserved 0 Foundation for modern thinking in this eld and many others PreSocratics The Ionians o Paimenides Pythagoras Anaxagoras Anaximander Heraclitus Question How is it than anything exists Method Theoretical and numerical relationships Answers Human senses are con ned to the realm of aggearances what is true Heraclitus you can t step into the same river twice Palmenides whatever is real must be eternal and unchanging such real existence can never be discovered by the senses It is contradictory to attribute existence to something that is never the same at different times Sophists o Meno Protagoras lof4 Psychology 30416014 Spring 2012 o sensationists 0 Man is the measure of all things Socratics reject the senses as routes to the truth Socrates 0 knowledge does not consist in impressions of sense but in reasoning about them 0 Memory experiences are recorded on something like wax impressions o Durability depends on frequency of impressions associationism and on the purity of the wax hereditary differences Plato o Cave Illusion perception and life goals interact o truth is subjective o topdown slant on perception o Rationalism 0 really nativism elitism 0 True knowledge comes from reasoning about the senses o in the ofthe knowledge Hippocrates Reliance on observation and empirical method Medical and anatomic observations le to knowledge of perception behavior health illness Aristotle Student of Plato Academy Moved on founded Lyceum Phases 1 senses respected but ideas still reign supreme very Platonic 2 observation critical for discovery uniquely his Soul derives from and is understood through study of the physical body Sensory deficits of young and old due to restlessness idue to a biologicalphysical change Naturalistic physiological empirical but not radically materialistic Soul does not equal mind mind lives in the soul imperishable Functions nutritive perceptive locomotor and in humans only universalizing function abstractioning Functions vary in level and sophistication based on biological differences between organisms Animals have sensory experiences since they have the organs In addition to the 5 senses there is a common sense sensus communis that integrates the other perceptions not common sense in modern Reidlike way The sensus communis is not a separate sense but rather a process common to all the other senses Perceptions set up vibrations or movements of the soul that result in memories the can and do decay This is very associationistic Senses do not convey knowledge rather they convey that from which the reasoning can extract knowledge 2of4 Psychology 30416014 Spring 2012 Stoics amp Epicureans Stoics Zeno Seneca Marcus Aurelius Epicureans Epicureus Lucretius Democritus Both schools were answering extreme even absurd teachings of Cynics and Skeptics who said that nothing can be known about anything Both taught that the universe consisted of some physical stuff energy atomic particulates re ether etc Epicureans all knowledge originates in sensation all experience due to physical interaction between matter of the world and matter of sense organ Stoics knowledge begins as the mental image of the sensory events Patristic Epictetus he who has sensations and pretends that he has not is worse than dead Transition from Roman to Christian era Melding of Greek and Christian views Monotheistic Origen Plotinus Augustine Christian Era Augustine examine nature and human behavior only to con rm the existence of God Nonsensory inner awareness of truth error moral right personal identity This inner sense consciousness but more than that it is a moral consciousness perhaps more like conscience Tactilevision theory perception results from physical interaction between the seen object and the eye Perception is an active process Discouraged scienti c examination of humans and human behavioriwe are not animals In general antiintellectualism Galen Scienti c Alternative Curing the sick a true practical clinician Experimenting done to improve health care Middle Ages Mostly religious near loss of much of science Modern Empiricism The Authority of Experience Scienti c scholarship Sensory evidence constitutes the primary data of all knowledge origin validity and utility of ideas sensation and re ection sensation is an active transaction Experience affects how sensations are interpreted e g blushingshame Topdown in uences on perception Compare to Plato Plato is more subj ectivistic Practical common sense modern de nition Rationalism we have only understood something when we can supply the reason for its being what it is 7 backto nal causes like Aristotle innate ideas that which cannot be given by experience Rene Descartes Benedict Spinoza 3of4 Psychology 30416014 02082012 GUSTATION TASTE 1 Tastes Basic qualities Proximal EXAM Proximal vs Distal a Salty i Detect Sodium Na ions ii Salary elephants in caves b Sour i Detect acids hydrogen ions ii Associated with decay 1 What not to eat K 2 A lot of things don t really smell that O D 0 bad but they do TASTE really bad c Sweet i Tquot i Detect Sugars i ii Nearly all sweet foods are god to eat d Bitter i Alkaloids o en associated with poisons e Umami i From MSG ii Present in many foods iii Can accentuate sweet and salty avors iv Possibly a separate receptor for it C Fattyacid i Detect fats ii Also seems to have separate receptors iii More sensitivity gets you to your set point sooner and you will stop eating iv OR you enjoy it more so you stuff your fat face g These are not universally recognized as tastes lofS Psychology 30416014 02082012 2 Receptors Four Types at least On the ends of taste cells Each receptor responds to different chemicals Likely all or at least several receptor types on each taste cell Note Not necessarily the case that each taste comes from only one receptor 3 Tongue a Taste cells i Each connected to nerve ber Su w u nonw b Taste buds i Clusters of taste cells 1 Like sections of an orange ii 50 150 taste cells per bud 5mm iii Compare to cupula in vestibular sense quotm We iv Located near surface of tongue in folds and valleys v N10000 taste buds vi Example of one to many 1 Very good for sensitivity levels Tm um and up at we can mimmm swam n 1 339 king m c Papillae i Fungiforrn papillae 1 Front 23 of tongue 2 Contain N8 taste buds each 3 Also pressure touch temperature receptors ii Circumvallate papillae 1 Back 13 oftongue iii Foliate papillae 1 Sides and back folds iv Filiform papillae 1 Front sides 2 Do not contain taste buds 2of5 Psychology 30416014 02082012 Venhal mszemmmax anmy gustamrv cunex 4 Pathway nucleus m was In a Nerves Exam How many cranial nerves are there 12 i Chorda tympani 1 Branch of 7Lh cranial nerve facial 2 Form front anterior of tongue 3 Passes through middle ear near Lale39sl 4 Tympanic membrane r ypalhalamns ii Glossopharyngeal nerve 9m 1 Lingual branch 35351ch i 39 2 From posterior part of tongue Gama mm iii Vagus nerve 10m j 1 From palate and epiglottis quot5 igure 7 30 b Medulla i Nucleus of solitary tract Neural pulhwnysol m gulclary 5yslm c Thalarnus i Ventral posteromedial VPM thalarnic nucleus d Primary gustatory cortex i Frontal insula amp opercular cortex e Secondary gustatory cortex i Orbitofrontal cortex f Note pathway is ipsilater a1 3of5 Psychology 30416014 02082012 5 Coding a Nerve bers tend to respond to one taste qyality better than to others but not to only one b Taste seems to be a combination of speci c innervation and distributed signal summation i Afferent code ii Across apopulation of bers c Neurons in cortex some respond to only one taste others respond to several tastes 6 Thresholds a Temperature b Genetics Elfigure 175 anesnom values or the tow xasie qualmes 3er muesnmea bv c Age 4of5