Sensation and perception:
Touch, taste and smell
How touchy are you?
In this simple lab you will work with a partner to
answer the following questions.
• How many different types of touch receptors
are there on the body?
• How are touch receptors distributed?
• What types of sensation/stimuli is skin
sensitive to?
Layers of skin
The skin is a densely
layered organ with
embedded touch
receptors, sweat
glands, hairs etc.
Types of touch
receptors:
• Light pressure
• Deep pressure
• Pain
• Temperature
Touch lab: Part 1
• Pair up: experimenter and subject
• Subject: offer your arm, hands, neck, face (not near
eyes), back and legs for experimentation!
• Experimenter will test the subject’s perception of:
1. Light touch – with a hair
2. Deep touch (pressure) – with curved part of a paperclip
(NOT sharp side)
3. Thermoreception (temperature) – with a heated or
cooled paperclip
4. Two-point discrimination – with the pointy ends of two
paperclips
Questions – write and answer
1. How many different types of touch receptors are
there on the body?
2. How are touch receptors distributed?
3. What types of sensation/stimuli is skin sensitive
to?
4. Which parts of the body that we tested today
are most sensitive and why?
5. Imagine you couldn’t feel any pain. How long
would you survive?
6. What are some errors or inconsistencies in the
way this lab was conducted?
Taste:
Taste – chemical sense
• Experimenter dips CLEAN cotton bud into a
solution
• Rubs on a zone (shown in diagram) of tongue.
Ask if can taste. Write + or – in diagram to
document if subject can taste or not.
• Repeat using NEW cotton bud but same
solution. Try all other zones on tongue.
Olfaction – chemical sense
• Place clove oil-soaked cotton bud one foot
under nose. Block left nostril, inhale deeply
with right and smell. Gently fan the aroma
towards your nose.
• Record time it takes till you can no longer
smell it, or not much.
• Change to peppermint oil. Repeat process.
Jelly bean discrimination activity
• Pair up, one is experimenter, other is subject.
• Experimenter feeds subject. The swa roles.
• Subject must eat bean
– Seeing it first
– Without seeing if first
– ALWAYS start chewing bean with nose plugged, try
to guess flavor
– Unplug nose – guess again
– Try two beans at once – can tell difference?
Sense of Taste: the microvilli in taste cells have receptor proteins that detect molecules
that allow the brain to distinguish between different tastes.
in adults nearly 3,000 taste buds are located on the tongue
Most taste buds are located on the wall of the papillae (bumps on tongue)
There are four primary types of taste: sour, sweet, salty and bitter
Each type of taste is sensitive to different taste buds which are located in different
places.
The taste bud opens at a taste pore
The taste bud has supporting cells and elongated taste cells that end in microvilli.
Molecules bind to receptor proteins, allowing nerve impulses to generate in sensory
nerve fibers that go to the brain. When reaching the gustatory cortex, they are then
interpreted as a unique taste.