Psy280: Perception Prof. Anderson Department of Psychology Chemical senses
Chemical senses:  Your are what you eat (smell) <ul><li>What’s it good for? </li></ul><ul><ul><li>Chemical composition of ...
Comparative taste <ul><li>Not all organisms “taste” with a tongue </li></ul>Moth antennae Fly “feet”
In good and bad taste <ul><li>Useful for the body </li></ul><ul><ul><li>Tend to taste good </li></ul></ul><ul><li>Potentia...
Taste in infancy <ul><li>Neonatal “liking” responses </li></ul><ul><li>Sweet </li></ul><ul><li>Lip smacking </li></ul><ul>...
Anatomy of taste: Papillae <ul><li>Filiform </li></ul><ul><ul><li>Cone shaped </li></ul></ul><ul><ul><li>All over the tong...
Anatomy of taste: The bud <ul><li>All papillae contain taste buds except the filiform </li></ul><ul><ul><li>Thus, centre o...
Taste sensory transduction <ul><li>Different taste cell types for different tastes </li></ul><ul><ul><li>Specificity at re...
Taste pathway <ul><li>Electrical signals carried by 3 pathways </li></ul><ul><ul><li>Chorda tympani </li></ul></ul><ul><ul...
Insular cortex and disgust <ul><li>Disgust = “bad taste” </li></ul><ul><li>Anterior insular cortex is primary taste area <...
Taste experience <ul><li>What tastes do we taste? </li></ul><ul><li>4 (maybe 5) basic tastes </li></ul><ul><ul><li>Sweet (...
Neural code for taste: Specificity <ul><li>Different taste receptors carry different dimensions of taste? </li></ul><ul><u...
Neural code for taste: Specificity <ul><li>4 different types of fibers in chorda tympani </li></ul><ul><li>Activation of s...
Problem with taste specificity coding <ul><li>Taste neurons response are a combination of quality (e.g. bitter) and intens...
Neural code for taste: Distributed coding <ul><li>Across fiber patterns </li></ul><ul><li>Emphasize degree of overlap betw...
Tastes differ <ul><li>Taste is dynamic </li></ul><ul><ul><li>Depends upon internal state: Hunger </li></ul></ul><ul><ul><l...
Flavor = Taste+smell <ul><li>Eating chocolate with a stuffed nose </li></ul><ul><ul><li>Where’s the flavor? </li></ul></ul...
Distal chemical sensing: Olfaction <ul><li>For many mammals it is the most important sense </li></ul><ul><ul><li>Identific...
 
Olfactory epithelium <ul><li>Olfactory mucosa </li></ul><ul><ul><li>Mucus! </li></ul></ul><ul><ul><li>High in nasal cavity...
Nose hair: Olfactory cilia <ul><li>ORN have cilia </li></ul><ul><li>Cilia contain olfactory receptor proteins </li></ul><u...
Smell blind <ul><li>Olfactory nerve passes through cribriform plate (skull) to reach OB </li></ul>
Smell antennae: Olfactory bulbs <ul><li>An outcropping of the brain </li></ul><ul><li>Its like a snail in your brain! </li...
How many receptor types are there? <ul><li>1000 different kinds of olfactory receptors (OR) </li></ul><ul><li>10 million O...
Mapping onto the bulb <ul><li>Similar ORN axons go to similar portions of the bulb </li></ul><ul><ul><li>Glomeruli (1000-2...
Distributed coding of smell <ul><li>Olfactory code is a complex pattern </li></ul><ul><li>Overlap across 1000 ORN types re...
Experience and identification of odors <ul><li>Can tell the difference between 10,000 odors </li></ul><ul><li>Distributed ...
Of mice and men <ul><li>Rats up to 50 times more sensitive to odors than humans </li></ul><ul><li>Dogs can be 10,000 times...
Rebuilding your neural nose: Olfactory neurogenesis <ul><li>Mucosa is exposed </li></ul><ul><ul><li>Not safely protected l...
What special about neural transmission in olfaction? <ul><li>Unlike other senses, short distance to brain </li></ul><ul><u...
What’s the neural code for smell? <ul><li>How does the brain know what of hundreds of chemicals are entering the nose? </l...
The hedonic primacy of olfaction <ul><li>Sensory and emotional experience </li></ul><ul><li>Not the same for vision/auditi...
What makes a bad smell  smell bad? <ul><li>Amygdala/piriform = intensity </li></ul><ul><li>Medial OFC = good </li></ul><ul...
The smell of attraction <ul><li>Attraction and symmetry </li></ul><ul><li>Symmetry associated with  </li></ul><ul><ul><li>...
Does the world smell  different to each nostril? <ul><li>Nostrils are different sizes </li></ul><ul><ul><li>Alternate ever...
Smell constancy: Little and big sniffs <ul><li>Intensity and concentration constancy </li></ul><ul><li>Do big sniffs make ...
Olfactory subliminal perception: Pheromones <ul><li>Odorless airborne chemicals can powerfully influence behavior </li></u...
ESP
Extrasensory perception: ESP <ul><li>The feeling of presences, being, or energy without use of the 5 basic senses </li></u...
Why is it possible? <ul><li>What have we learned? </li></ul><ul><ul><li>All about conscious perception </li></ul></ul><ul>...
Experiments on ESP:  Ganzfeld research <ul><li>All “sensory” information reduced </li></ul><ul><ul><li>Receiver in sound p...
Experiments on ESP:  Ganzfeld research At end of session… <ul><li>Receiver shown 4 pictures (3 decoys plus target) </li></...
Results <ul><li>1974-1997 </li></ul><ul><ul><li>50+ studies from 15 different labs  </li></ul></ul><ul><ul><li>Hit rate = ...
Problems <ul><li>Experimenter needs to be blind to target </li></ul><ul><li>Sensory “leakage” </li></ul><ul><ul><li>Sensor...
Magnetoreception <ul><li>Diverse animals can use the earth’s magnetic field as orientation cue </li></ul><ul><ul><li>North...
THE END
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Chemical senses - smell and taste

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Chemical senses - smell and taste, psychology 280 LECTURE 9

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Chemical senses - smell and taste

  1. 1. Psy280: Perception Prof. Anderson Department of Psychology Chemical senses
  2. 2. Chemical senses: Your are what you eat (smell) <ul><li>What’s it good for? </li></ul><ul><ul><li>Chemical composition of our surroundings </li></ul></ul><ul><li>Olfaction (i.e., smell) </li></ul><ul><ul><li>Distal/remote sensing </li></ul></ul><ul><ul><li>Small concentrations of airborne substances </li></ul></ul><ul><li>Gustation (i.e., taste) </li></ul><ul><ul><li>Proximal/immediate sensing </li></ul></ul><ul><ul><li>Check if appropriate to enter your body </li></ul></ul><ul><ul><li>Last sense to use </li></ul></ul><ul><ul><ul><li>If it looks like and it smells like, it probably is it </li></ul></ul></ul>
  3. 3. Comparative taste <ul><li>Not all organisms “taste” with a tongue </li></ul>Moth antennae Fly “feet”
  4. 4. In good and bad taste <ul><li>Useful for the body </li></ul><ul><ul><li>Tend to taste good </li></ul></ul><ul><li>Potentially harmful </li></ul><ul><ul><li>Tend to taste bad </li></ul></ul><ul><ul><li>Tend to taste bitter </li></ul></ul><ul><li>Not always the case: Influence of culture </li></ul><ul><ul><li>The burn of capsaicin </li></ul></ul><ul><ul><li>Bitterness </li></ul></ul><ul><li>Compare with vision </li></ul><ul><ul><li>All dangerous things ugly? </li></ul></ul><ul><ul><li>All ugly things dangerous? </li></ul></ul>
  5. 5. Taste in infancy <ul><li>Neonatal “liking” responses </li></ul><ul><li>Sweet </li></ul><ul><li>Lip smacking </li></ul><ul><li>Smiles </li></ul><ul><li>Bitter </li></ul><ul><li>Grimace </li></ul><ul><li>Lip retraction </li></ul><ul><li>Nose wrinkle </li></ul>
  6. 6. Anatomy of taste: Papillae <ul><li>Filiform </li></ul><ul><ul><li>Cone shaped </li></ul></ul><ul><ul><li>All over the tongue </li></ul></ul><ul><ul><li>Give rough appearance </li></ul></ul><ul><li>Fungiform </li></ul><ul><ul><li>Mushroom shaped </li></ul></ul><ul><ul><li>Tip & sides </li></ul></ul><ul><li>Foliate </li></ul><ul><ul><li>Folds at sides </li></ul></ul><ul><li>Circumvallate </li></ul><ul><ul><li>Flat mounds </li></ul></ul><ul><ul><li>At back </li></ul></ul><ul><li>Other taste receptors </li></ul><ul><ul><li>Palate </li></ul></ul><ul><ul><li>Larynx </li></ul></ul>
  7. 7. Anatomy of taste: The bud <ul><li>All papillae contain taste buds except the filiform </li></ul><ul><ul><li>Thus, centre of tongue is “taste-blind” </li></ul></ul><ul><li>Taste buds </li></ul><ul><ul><li>Multiple taste cells </li></ul></ul><ul><ul><li>Create taste pore </li></ul></ul>
  8. 8. Taste sensory transduction <ul><li>Different taste cell types for different tastes </li></ul><ul><ul><li>Specificity at receptor level </li></ul></ul><ul><li>Salt </li></ul><ul><ul><li>NaCl </li></ul></ul><ul><ul><li>Na+ entry into cell </li></ul></ul><ul><ul><li>Depolarization </li></ul></ul><ul><li>Sour </li></ul><ul><ul><li>H+ ions block channels </li></ul></ul>
  9. 9. Taste pathway <ul><li>Electrical signals carried by 3 pathways </li></ul><ul><ul><li>Chorda tympani </li></ul></ul><ul><ul><ul><li>Front & side </li></ul></ul></ul><ul><ul><li>Glosso-pharyngeal </li></ul></ul><ul><ul><ul><li>Back </li></ul></ul></ul><ul><ul><li>Vagus </li></ul></ul><ul><ul><ul><li>Mouth & larynx </li></ul></ul></ul><ul><li>NST (brainstem) </li></ul><ul><li>Gustatory thalamus </li></ul><ul><li>Primary taste areas </li></ul><ul><ul><li>Insular/opercular cortex </li></ul></ul><ul><li>Secondary taste areas </li></ul><ul><ul><li>Orbitofrontal cortex </li></ul></ul>
  10. 10. Insular cortex and disgust <ul><li>Disgust = “bad taste” </li></ul><ul><li>Anterior insular cortex is primary taste area </li></ul><ul><li>Viewing disgust faces increase activation </li></ul><ul><li>Lesions impair recognition of disgust </li></ul>Disgust vs fear
  11. 11. Taste experience <ul><li>What tastes do we taste? </li></ul><ul><li>4 (maybe 5) basic tastes </li></ul><ul><ul><li>Sweet (Sucrose), bitter (quinine), sour (HCl), salty (NaCl) </li></ul></ul><ul><ul><li>And … umami (MSG) </li></ul></ul><ul><li>All taste experience can be described in terms of their combinations </li></ul><ul><ul><li>Some substances are primarily 1 taste </li></ul></ul><ul><ul><ul><li>Sodium chloride: Salty </li></ul></ul></ul><ul><ul><ul><li>Quinine: Bitter </li></ul></ul></ul><ul><ul><li>Some are combinations </li></ul></ul><ul><ul><ul><li>Sodium nitrate: salty, sour, & bitter </li></ul></ul></ul>
  12. 12. Neural code for taste: Specificity <ul><li>Different taste receptors carry different dimensions of taste? </li></ul><ul><ul><li>Salt receptors related to saltiness? </li></ul></ul><ul><ul><li>Block receptors (amiloride)—> impair salt perception </li></ul></ul><ul><ul><li>Leaves other sensations intact </li></ul></ul><ul><li>Parallel between receptor morphology and taste </li></ul><ul><ul><li>E.g., circumvallate (back) = bitter? </li></ul></ul><ul><ul><li>Foliate (side) =sour? </li></ul></ul>
  13. 13. Neural code for taste: Specificity <ul><li>4 different types of fibers in chorda tympani </li></ul><ul><li>Activation of specific fiber tracts responsible for taste sensations </li></ul><ul><ul><li>E.g. “sweet”, “bitter” neurons </li></ul></ul>
  14. 14. Problem with taste specificity coding <ul><li>Taste neurons response are a combination of quality (e.g. bitter) and intensity </li></ul><ul><li>E.g., same magnitude of response in “bitter” neuron </li></ul><ul><ul><li>A high concentration of sucrose </li></ul></ul><ul><ul><li>low concentration of quinine </li></ul></ul><ul><li>Similar to colour vision </li></ul><ul><ul><li>Neurons response a result of wavelength and intensity </li></ul></ul><ul><ul><li>Need 2 or more receptors to resolve ambiguity </li></ul></ul>
  15. 15. Neural code for taste: Distributed coding <ul><li>Across fiber patterns </li></ul><ul><li>Emphasize degree of overlap between fibers </li></ul><ul><li>Idea: More overlap—> greater taste similarity </li></ul><ul><ul><li>Relative to ammonium chloride (NH 4 Cl) </li></ul></ul><ul><ul><li>NaCl more distinct than KCl </li></ul></ul><ul><li>Correlation between taste and across fiber pattern </li></ul>
  16. 16. Tastes differ <ul><li>Taste is dynamic </li></ul><ul><ul><li>Depends upon internal state: Hunger </li></ul></ul><ul><ul><li>Adaptation/Sensory-specific satiety (SSS) </li></ul></ul><ul><ul><ul><li>Peripheral </li></ul></ul></ul><ul><ul><ul><li>Chewing, smelling induces SSS </li></ul></ul></ul><ul><ul><ul><li>Sweet desserts follow savory meals </li></ul></ul></ul><ul><ul><li>Alliesthesia </li></ul></ul><ul><ul><ul><li>Central </li></ul></ul></ul><ul><ul><ul><li>Changed pleasantness that is not sensory based </li></ul></ul></ul><ul><ul><ul><li>Decreased pleasantness of sucrose when tubed into stomach </li></ul></ul></ul><ul><ul><ul><li>Animals change diet based on nutritional needs </li></ul></ul></ul><ul><li>Individual differences </li></ul><ul><ul><li>Experience: culture </li></ul></ul><ul><ul><li>Genetics: tasters and nontasters </li></ul></ul><ul><ul><ul><li>saccharin (bitter or tasteless) </li></ul></ul></ul>
  17. 17. Flavor = Taste+smell <ul><li>Eating chocolate with a stuffed nose </li></ul><ul><ul><li>Where’s the flavor? </li></ul></ul><ul><li>Taste Identification is impaired without smell </li></ul><ul><li>What we call taste is really an interaction between our chemical senses </li></ul><ul><li>Locate taste as occurring in the mouth </li></ul><ul><ul><li>Taste nerves carry somatosensory/texture info as well </li></ul></ul>Like visual capture
  18. 18. Distal chemical sensing: Olfaction <ul><li>For many mammals it is the most important sense </li></ul><ul><ul><li>Identification </li></ul></ul><ul><ul><ul><li>Smell “face” </li></ul></ul></ul><ul><ul><li>localization </li></ul></ul><ul><li>We are vision/hearing dominate mammals </li></ul><ul><ul><li>Under-appreciate/under-use our sense of smell </li></ul></ul>
  19. 20. Olfactory epithelium <ul><li>Olfactory mucosa </li></ul><ul><ul><li>Mucus! </li></ul></ul><ul><ul><li>High in nasal cavity </li></ul></ul><ul><ul><li>Site of transduction </li></ul></ul><ul><ul><li>Contains olfactory receptor neurons (ORN) </li></ul></ul>
  20. 21. Nose hair: Olfactory cilia <ul><li>ORN have cilia </li></ul><ul><li>Cilia contain olfactory receptor proteins </li></ul><ul><ul><li>Similar to visual pigment </li></ul></ul><ul><li>Transduction </li></ul><ul><ul><li>Odorants bind to ORs </li></ul></ul><ul><ul><li>Change shape of protein </li></ul></ul><ul><ul><li>Ion flow across OR </li></ul></ul><ul><ul><li>Electricity </li></ul></ul>
  21. 22. Smell blind <ul><li>Olfactory nerve passes through cribriform plate (skull) to reach OB </li></ul>
  22. 23. Smell antennae: Olfactory bulbs <ul><li>An outcropping of the brain </li></ul><ul><li>Its like a snail in your brain! </li></ul><ul><li>Electrical responses in cilia passed through olfactory nerve to OB </li></ul>Chemotaxis
  23. 24. How many receptor types are there? <ul><li>1000 different kinds of olfactory receptors (OR) </li></ul><ul><li>10 million OR neurons </li></ul><ul><ul><li>10,000 of each type of OR </li></ul></ul><ul><ul><li>Each OR neuron has only one type of receptor </li></ul></ul><ul><ul><li>1000 neuronal chemical detectors </li></ul></ul><ul><li>Compare to visions 4 receptor types (3 cones, 1 rod) </li></ul>
  24. 25. Mapping onto the bulb <ul><li>Similar ORN axons go to similar portions of the bulb </li></ul><ul><ul><li>Glomeruli (1000-2000) </li></ul></ul><ul><ul><li>Inputs mainly from 1 ORN </li></ul></ul><ul><ul><li>Thus, each glomerulus responds to similar compounds </li></ul></ul><ul><ul><ul><li>Like orientation columns in visual cortex </li></ul></ul></ul><ul><li>Glomeruli coding </li></ul><ul><ul><li>Similar structure, not smell </li></ul></ul><ul><ul><li>Odotope maps </li></ul></ul><ul><ul><ul><li>Mapping of similar chemical features </li></ul></ul></ul>
  25. 26. Distributed coding of smell <ul><li>Olfactory code is a complex pattern </li></ul><ul><li>Overlap across 1000 ORN types represents smell quality </li></ul><ul><li>Number of receptors would suggest specificity coding </li></ul><ul><li>Millions of colours can be perceived with 3 cones </li></ul><ul><li>How many odors? </li></ul>
  26. 27. Experience and identification of odors <ul><li>Can tell the difference between 10,000 odors </li></ul><ul><li>Distributed coding suggests much greater number </li></ul><ul><li>Poor at identification </li></ul><ul><ul><li>Vision dominates </li></ul></ul><ul><ul><li>Get better with experience </li></ul></ul>
  27. 28. Of mice and men <ul><li>Rats up to 50 times more sensitive to odors than humans </li></ul><ul><li>Dogs can be 10,000 times more sensitive </li></ul><ul><ul><li>Yet olfactory receptors equally sensitive </li></ul></ul><ul><ul><li>1 molecule can stimulate an olfactory receptor </li></ul></ul><ul><ul><ul><li>Can’t get more sensitive than that! </li></ul></ul></ul><ul><ul><li>Many more receptors (1 billion compared to 10 million) </li></ul></ul><ul><ul><ul><li>Decreases # of molecules needed for neural response </li></ul></ul></ul><ul><li>Expertise </li></ul><ul><ul><li>Wine tasters don’t get more sensitive w/ their nose </li></ul></ul><ul><ul><li>Better at retrieving labels from memory </li></ul></ul>
  28. 29. Rebuilding your neural nose: Olfactory neurogenesis <ul><li>Mucosa is exposed </li></ul><ul><ul><li>Not safely protected like photoreceptors or auditory cilia </li></ul></ul><ul><li>Unlike vision/audition receptors regenerate </li></ul><ul><ul><li>Every 5-7 weeks </li></ul></ul><ul><ul><li>Axons have to find way to bulb </li></ul></ul><ul><ul><ul><li>Create new synapses </li></ul></ul></ul><ul><ul><li>Constant rebuilding olfactory system </li></ul></ul>
  29. 30. What special about neural transmission in olfaction? <ul><li>Unlike other senses, short distance to brain </li></ul><ul><ul><li>Vision/audition have many synapses between retina and brain </li></ul></ul><ul><li>Central destinations of olfactory information from bulb </li></ul><ul><ul><li>Primary olfactory cortex (piriform cortex) </li></ul></ul><ul><ul><li>Secondary olfactory cortex (orbitofrontal cortex) </li></ul></ul><ul><ul><li>Amygdala </li></ul></ul><ul><li>Unlike other senses, no mandatory thalamic relay </li></ul>
  30. 31. What’s the neural code for smell? <ul><li>How does the brain know what of hundreds of chemicals are entering the nose? </li></ul><ul><li>Don’t really know </li></ul><ul><li>Odor quality </li></ul><ul><ul><li>Related to physical/chemical properties? </li></ul></ul><ul><ul><ul><li>e.g., structure of molecule </li></ul></ul></ul><ul><ul><ul><li>Odotopes in olfactory bulb (OB) </li></ul></ul></ul><ul><ul><li>Similarly structured molecules smell the same? </li></ul></ul><ul><ul><ul><li>Not necessarily </li></ul></ul></ul><ul><ul><li>Differently structured molecules smell different? </li></ul></ul><ul><ul><ul><li>Not necessarily </li></ul></ul></ul><ul><li>Thus, not easy to relate smell with physicochemical properties of stimulus or OB maps </li></ul>
  31. 32. The hedonic primacy of olfaction <ul><li>Sensory and emotional experience </li></ul><ul><li>Not the same for vision/audition </li></ul><ul><ul><li>Seeing and feeling more distinct </li></ul></ul><ul><li>More intertwined in the chemical senses </li></ul><ul><ul><li>Why? </li></ul></ul><ul><li>Orbitofrontal cortex </li></ul><ul><ul><li>Plays dual role </li></ul></ul><ul><ul><li>Critical for emotional </li></ul></ul><ul><ul><li>experience </li></ul></ul><ul><ul><li>Secondary sensory </li></ul></ul><ul><ul><li>cortex for olfaction </li></ul></ul>
  32. 33. What makes a bad smell smell bad? <ul><li>Amygdala/piriform = intensity </li></ul><ul><li>Medial OFC = good </li></ul><ul><li>Lateral OFC = bad </li></ul>
  33. 34. The smell of attraction <ul><li>Attraction and symmetry </li></ul><ul><li>Symmetry associated with </li></ul><ul><ul><li>immune system health, healthy development </li></ul></ul><ul><ul><li>Pleasant odor </li></ul></ul>
  34. 35. Does the world smell different to each nostril? <ul><li>Nostrils are different sizes </li></ul><ul><ul><li>Alternate every few hours which is bigger! </li></ul></ul><ul><ul><li>Airflow in each nostril differs </li></ul></ul><ul><li>Odorants attachment to mucosa depends on airflow </li></ul><ul><ul><li>Some better at low vs high and vice versa </li></ul></ul><ul><li>Provides two olfactory images of the world </li></ul><ul><ul><li>Result: better olfactory acuity </li></ul></ul>
  35. 36. Smell constancy: Little and big sniffs <ul><li>Intensity and concentration constancy </li></ul><ul><li>Do big sniffs make for more intense smells? No </li></ul><ul><li>Sniff activity in piriform </li></ul><ul><li>cortex </li></ul>Magnitude estimation for odor strength equal
  36. 37. Olfactory subliminal perception: Pheromones <ul><li>Odorless airborne chemicals can powerfully influence behavior </li></ul><ul><ul><li>Sexual behaviour </li></ul></ul><ul><ul><li>Mood </li></ul></ul><ul><ul><li>Menstrual synchronization </li></ul></ul><ul><ul><li>Bruce effect: Aborted fetus </li></ul></ul><ul><li>Accessory olfactory system </li></ul><ul><ul><li>Vomeronasal organ (VNO) </li></ul></ul><ul><ul><li>Not sure if functional in humans </li></ul></ul><ul><ul><li>Like extrageniculostriate visual pathway </li></ul></ul><ul><ul><ul><li>Nonconscious vision </li></ul></ul></ul>
  37. 38. ESP
  38. 39. Extrasensory perception: ESP <ul><li>The feeling of presences, being, or energy without use of the 5 basic senses </li></ul><ul><li>The problem with ESP is that it is “extrasensory” </li></ul><ul><li>Sensory systems are the receivers of environmental stimulation </li></ul><ul><li>Without a receiver there is no perception </li></ul><ul><ul><li>Tree falls in a forest </li></ul></ul><ul><li>Subliminal is sensory (e.g., visual, olfactory, auditory), but nonconscious </li></ul><ul><ul><li>Below subjective threshold for perception </li></ul></ul><ul><ul><li>Brain can discriminate thingsto which we don’t have conscious access </li></ul></ul><ul><ul><ul><li>E.g., amygdala and “unseen” fear </li></ul></ul></ul>
  39. 40. Why is it possible? <ul><li>What have we learned? </li></ul><ul><ul><li>All about conscious perception </li></ul></ul><ul><ul><li>Guides our own investigations </li></ul></ul><ul><ul><ul><li>Colour, motion, depth, pitch, smell, taste, etc. </li></ul></ul></ul><ul><ul><li>Bias in what “phenomena” we investigate </li></ul></ul><ul><li>ESP might represent sensory systems that are functional but unknown </li></ul><ul><ul><li>Don’t represent conscious information processing </li></ul></ul><ul><ul><ul><li>E.g. discovery of new photoreceptor that regulates circadian rhythms </li></ul></ul></ul><ul><ul><li>Electromagnetic waves outside the visual spectrum </li></ul></ul>
  40. 41. Experiments on ESP: Ganzfeld research <ul><li>All “sensory” information reduced </li></ul><ul><ul><li>Receiver in sound proof chamber with ping pong balls on eyes, earphones w/ white noise </li></ul></ul><ul><ul><li>Reduce external sensory “noise” to enhance sensitivity to weak signal </li></ul></ul><ul><ul><li>Progressive relaxation: Decrease internal somatic noise </li></ul></ul>Target randomly chosen sender attempts to ‘psychically’ send target to receiver receiver reports imagery trees... buildings... clouds...
  41. 42. Experiments on ESP: Ganzfeld research At end of session… <ul><li>Receiver shown 4 pictures (3 decoys plus target) </li></ul><ul><li>Must rate each picture in terms of matching imagery </li></ul><ul><li>25% chance of rating target picture highest </li></ul>
  42. 43. Results <ul><li>1974-1997 </li></ul><ul><ul><li>50+ studies from 15 different labs </li></ul></ul><ul><ul><li>Hit rate = 33.2%, significantly different from chance (25%) </li></ul></ul><ul><ul><li>Dynamic targets better than static (37% vs 27%) </li></ul></ul><ul><ul><li>Higher rates when a friend versus stranger is the sender (44% vs 26%) </li></ul></ul><ul><ul><li>50% hit rate for “artistic” students (n=20) </li></ul></ul><ul><ul><ul><li>Julliard students </li></ul></ul></ul>
  43. 44. Problems <ul><li>Experimenter needs to be blind to target </li></ul><ul><li>Sensory “leakage” </li></ul><ul><ul><li>Sensory cues from use of same target </li></ul></ul><ul><li>The file drawer problem </li></ul><ul><ul><li>How many studies not showing effect unreported? </li></ul></ul><ul><li>What are the limits of this perception? </li></ul><ul><ul><li>Send over telephone wire? </li></ul></ul><ul><li>Reading other minds </li></ul><ul><ul><li>Would be difficult to home in on one signal </li></ul></ul><ul><ul><li>Potentially insulting too! </li></ul></ul>
  44. 45. Magnetoreception <ul><li>Diverse animals can use the earth’s magnetic field as orientation cue </li></ul><ul><ul><li>North/south axis, and local magnetic fields </li></ul></ul><ul><li>Magnetic map sense </li></ul><ul><ul><li>Like having an internal GPS </li></ul></ul><ul><ul><li>Homing pigeons, spiny lobsters </li></ul></ul><ul><ul><ul><li>Placed in novel location </li></ul></ul></ul><ul><ul><ul><li>Don’t monitor outward journey </li></ul></ul></ul><ul><ul><ul><li>Can navigate back </li></ul></ul></ul><ul><li>Know very little about the physiological mechanisms </li></ul><ul><li>No obvious receptors </li></ul><ul><ul><li>Accessory structures usual focus sensory stimuli on sensory surface </li></ul></ul><ul><ul><ul><li>Lenses: vision </li></ul></ul></ul><ul><ul><ul><li>Outer ear: audition </li></ul></ul></ul><ul><ul><li>Biomaterials don’t affect magnetic field lines </li></ul></ul>
  45. 46. THE END
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