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Touch, Taste, & Smell
Kimberley A. Clow
http://instruct.uwo.ca/psychology/215a-570
Outline
� Touch– Biology– Pain– Haptics
� Taste– Biology– Individual Differences
� Smell– Biology– Interesting Effects
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
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Importance of Touch
Receptors
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Two Pathways
� Medial-Lemniscal Pathway– carries basic touch
information
– through white matter of spinal cord to medulla
– crossover to the contralateralside of the body
– through the medial lemniscusto the ventral posterior nucleus of the thalamus
� Spinothalamic Pathway– carries pain and
temperature information
– crossover to contralateralside at spinal cord
– ascends thru the spinothalamic tract to the ventral posterior nuclei of the thalamus
Cortex
Mot
or C
orte
x
Som
atos
enso
ryCor
tex
Posterior Parietal Cortex involved in touch
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Mapping the Brain
Star-Nosed Mole
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Effects of Experience
Monkey
Human
Pain
� Survival Function
� Free Nerve Endings– pressure
– heat & cold
– chemical damage » lactic acid, stings
� Two Pathways
� Pain Perception– Biological
– Psychological
– Cultural
Gate Control Theory
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Acupuncture
Limbic System
Somatosensory Cortex
Touch Acuity
Haptic Exploration
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Applied Haptics
Taste & Smell
� Taste = Gustation
� Smell = Olfaction– Both are chemical
sensations
– Interdependent
Taste
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Taste Receptors
bittersoursaltysweet
Oversimplification
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Central Pathway
Cortex
Individual Differences
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Identifying Supertasters
Identifying Tastes
Taste & Smell
� Durian Fruit– Smells horrible
– Tastes delicious
� Can’t tell the difference between grated apple and grated onion without smell
Durian Fruit
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Smell
Receptors
Central Pathway
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Cortex
Identification
Recognition
Detection
Pheromones
� Definition– Chemical signals
found in natural body scents
� Truffle pigs
� Human reactions– McClintock Effect
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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)
Smell & Memory
� Smell evokes memories
� 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
� Smell better cue for memory than touch or audition