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Touch, Taste, & Smell

Kimberley A. Clow

kclow2@uwo.ca

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