Senses
Observation Labs
How we Begin to wonder
How we gather data
Using your Senses
Do you sense what you think you sense?
Your Senses 1
Sight 
for many people, sight is their primary way of
learning things!
There are 2 types of receptors, Rods and
Cones
Rods are more sensitive - monochromatic
and used at night
Cones sense colors, and are packed in the
center of the visual field for best clarity.
Cones are Red – Green – Blue detectors
Your Senses 2
Hearing

You get a lot of information in school via hearing!
Pressure waves funnel into your ear, vibrate
the eardrum and 3 small bones, and are
transferred to the Cochlea. This vibrates in
different parts depending on the frequency
and the information is sent to the brain. Loud
noises can damage the sensory cells in the
cochlea.
The typical frequency range is 20Hz – 20,000
Hz when young. You lose the high
frequencies as you age.
Your Senses 3
Tasting

Perhaps the weakest of the senses
You actually only have 4 types of taste
sensors – Sweet, Sour, Salty, Bitter!
From those 4 tastes (with your sense of
smell helping) – you experience your
food.
There are proposals for 1 or 2 other tastes – umami
(glutamate – MSG) and “fat”
Your Senses 4
Feeling / Touch

Like Taste and Vision, there are only 4
touch sensations or receptor cells.
Pain - Pressure - Hot - Cold
Touch receptors are not evenly placed
on the body – there are more in your
fingers, less on your elbow!
Your Senses 5
Smelling

“stink” is a rather vague term 
There are more than 3000 different
smells you can detect.
The nose contains receptors for
different molecule shapes.
Smell is the “oldest” sense. And is more
directly wired into the brain than others.
Your Senses 6???
ESP?
Extra Sensory Perception – Mind
Reading, Detecting Auras,
Clairvoyance, and more. People claim
to have these powers, but they haven’t
been proven* in experiments.

*the hypothesis has not been supported
Observations vs Inference
Observations are those sensations we
receive via our 5 senses.
Inferences are what we think we sense,
based on the sensations we have
received and past experience.
Observations vs. Inference 2
Example 1 - you hear a whistling sound
outside (observation) and say it is a bird
(inference). Of course, it may have been
a tape of a bird! Or a Space Alien!
Example 2 - you see an unusual light in
the sky (observation) and say it is an
Alien Spacecraft (Inference)

2 “true” UFO stories
Observation Lab 1
The inside of an eye

The Retina
 Why you get “red-
eye” in flash pictures.

Optic Nerve
 The Blind Spot

Blood Vessels
Observation Lab1
Blind Spot
Hole in the Hand – Floating Sausage(s)
Optical Illusions
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Straight Lines? Afterimages
Motion / Cube or ?
Color Blindness
Write up your observations in your
noteboook and Show it to me.
Observation Lab1
Blind Spot
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An easy lab, but a little spooky –
Get out a piece of paper, and make a small
+ on it, about 10 cm away (4 inches) put a
dot. The dot can be about 2-4mm across
Hold the paper with the dot on the right –
close your left eye – stare at the cross.
Slowly bring the paper close – you will
notice the dot disappears!!!
Flip the paper over, and do it with your
Right eye closed.
Observation Lab1
Hole in the Hand

Roll up a tube of paper – hold it in your
right hand, and put it up to your right eye.
Hold your left hand next to the middle of
the tube! It looks like you are looking
through your hand
Floating Sausage

Put two fingers pointing at each other in
front of your eyes. See the “sausage”
floating between them.
Observation Lab1
Optical
Illusions 1
Observation Lab1
Optical
Illusion 2
Observation Lab1
Optical Illusions 3
Observation Lab1
Optical Illusion 4
Observation Lab1
Optical Illusion 5
Observation Lab1
Optical Illusion 5.1
Observation Lab1
Optical Illusion 6
Observation Lab1
Optical Illusion 6.1
Observation Lab1
Optical Illusion 7
Observation Lab1
Optical Illusion 7.1
Observation Lab1
Optical Illusion 7.2
Observation Lab1
Optical Illusion 8
Observation Lab1
Optical Illusion 9
Observation Lab1
Optical Illusion 10
Observation Lab1
Optical Illusion 10.1
Observation Lab1
Optical Illusion 11
Observation Lab 2
Listening
Like some of the visual illusions, there
are also Auditory ones. Here is the ever
descending tone.
B
A
http://asa.aip.org/sound/cd/demo27b.au
Observation Lab 2.1
Listening
This is the most difficult lab this year you have to be silent for 20 minutes,
and write down everything you hear.
Please do not deliberately make noise!
Start when I say so: Stop when I say so.
Observation Lab 2.2
Look at your listing. How many of the
things you wrote down are true
Observations (A description of What
you sensed) -and how many were
Inferences (What you think caused the
sound)
Write a Summary comment and
Conclusion and turn it in.
Observation Lab 3 - ec
Tasting - a Map of the Tongue
You only taste 4 basic taste sensations!
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Sweet
Salty
Sour
Bitter
Each taste has it’s special place on the
tongue. Using the taste samples – make
a map!
Observation Lab 4 - ec
Feeling – Touch
How Close are the receptor cells?


With two probes – find out how far away
they must be before you can tell there are
two! Try the fingers, arm, elbow!
With one probe, try and find an example of
each type of cell.
Observation Lab 5 - ec
Smell
This lab is a homework assignment - you will
need the help of a brother or sister (or mom
or dad)
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Slice a wedge of onion and a wedge of apple.
Don’t let anyone see you.
Blindfold your subject
Hold the onion under their nose and have them
bite the apple.
Ask them what they think they ate.
Observation Lab 6
ESP
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If you want to do this lab at home, or…
Take a deck of cards (beware of contraband) To
test “telepathy” you look at a card, thinking of its
suit (Hearts, Clubs, Diamonds, Spades). Your
friend has to tell you what suit it is.
For each correct answer – put the card on a
“correct” pile. For each wrong answer – the
“wrong” pile.
Random guessing suggests about 13 cards in the
correct pile, after going through the deck. Keep
records!!!
Questions?
Disclaimer
Aloha
I put together these power points for use in
my science classes.
You may use them in your classes.
Some images are public domain, some
are used under the fair-use provisions of
the copyright law, some are mine.
Copyright is retained by the owners!
Ted Brattstrom