2. Touch, Taste, & Smell Kimberley A. Clow kclow2@uwo.ca http://instruct.uwo.ca/psychology/215a-570

3. Outline Touch Touch –Biology –Pain –Haptics Taste Taste –Biology –Individual Differences Smell Smell –Biology –Interesting Effects

4. Touch Our skin is our largest sensory system Touch allows us to explore and manipulate the world –tactile exploration –assessment of textures –feedback from object manipulation Touch is more “trustworthy” than other senses

5. Importance of Touch

6. Receptors

9. Two Pathways Medial-Lemniscal Pathway Medial-Lemniscal Pathway –carries basic touch information –through white matter of spinal cord to medulla –crossover to the contralateral side of the body –through the medial lemniscus to the ventral posterior nucleus of the thalamus Spinothalamic Pathway –carries pain and temperature information –crossover to contralateral side at spinal cord –ascends thru the spinothalamic tract to the ventral posterior nuclei of the thalamus

10. Cortex Motor Cortex Somatosensory Cortex Posterior Parietal Cortex involved in touch

11. Mapping the Brain

13. Star-Nosed Mole

14. Effects of Experience Monkey Human

15. Pain Survival Function Free Nerve Endings –pressure –heat & cold –chemical damage »lactic acid, stings Two Pathways Pain Perception –Biological –Psychological –Cultural

16. Gate Control Theory

17. Acupuncture Limbic System Somatosensory Cortex

18. Touch Acuity

19. Haptic Exploration

20. Applied Haptics

21. Taste & Smell Taste = Gustation Smell = Olfaction –Both are chemical sensations –Interdependent

22. Taste

23. Taste Receptors

25. bitter sour salty sweet Oversimplification

26. Central Pathway

27. Cortex

28. Individual Differences

29. Identifying Supertasters

30. Identifying Tastes

31. Taste & Smell Durian Fruit –Smells horrible –Tastes delicious Can’t tell the difference between grated apple and grated onion without smell Durian Fruit

32. Smell

33. Receptors

34. Central Pathway

35. Cortex

36. Identification Recognition Detection

37. Pheromones Definition –Chemical signals found in natural body scents Truffle pigs Human reactions –McClintock Effect

38. Anosmia “I always thought I would sacrifice smell to taste if I had to choose between the two, but I suddenly realized how much I had missed. We take it for granted and are unaware that everything smells: people the air, my house, my skin” --anosmic patient (Birnberg,1988, in Ackerman, 1990)

39. Smell & Memory Smell evokes memories Smell evokes memories Damage to memory regions in temporal lobe does not affect ability to detect smell Damage to memory regions in temporal lobe does not affect ability to detect smell –Deficits in odour identification! Strong aversions develop when smell is associated with negative experiences Strong aversions develop when smell is associated with negative experiences Smell better cue for memory than touch or audition Smell better cue for memory than touch or audition