Human Senses Lab – Day 1

Purpose: To investigate the various human senses.

Materials:

Metric ruler

Paper

Pen

Cotton Swabs

Various Solutions

Skittles

Tuning Fork

Part A: Vision

Blind Spot Determination

Because no photoreceptors are found in the area where the optic nerve is attached to the retina, this area is called the blind spot. To locate your blind spot, look at the symbols below. Center and hold this page about 50cm in front of your eyes so that the + is on your left. Close your right eye and focus your left eye on the ∙. Slowly move the page toward your eyes while looking at the ∙.

+

  1. Does the cross disappear? This is known as the blind spot.
  2. Using a ruler, have your partner measure the distance between your eyes and the page. At what distance from your eyes do you reach your blind spot?
  3. Continue to move the page toward you. What happens to the cross?
  4. Repeat the process using your right eye and focusing on the cross. Does the circle disappear?
  5. At what distance from your eyes do your reach your blind spot in your right eye?
  6. What happens to the circle as your continue to move the page towards you?

Dominant Eye Determination

Most individuals do not make use of both eyes. They depend more heavily on one eye – the dominant eye.

  1. Roll a sheet of paper into a tube approximately 4cm in diameter.
  2. Hold the tube at arm’s length. Look through it with both eyes at some object across the room.
  3. With the tube held steady, close one eye then the other. Which eye still sees the object through the tube? This is your dominant eye. Is it on the same side as your dominant hand?

Afterimage

  1. Look at a bright light for 20 seconds. DO NOT LOOK AT THE SUN!
  2. Now look at the wall or ceiling. Describe what you see.
  3. Repeat the process and have your partner time the length of the period that the after image stays with you.
  4. Alternative Retinal Burn Test:

Snellen Eye Test

  1. Make sure you are 20 feet away from the chart. Be sure the room you are in is well lit but not in full sunlight
  2. Test one eye at a time, covering your other eye with your and or a card. The lowest line that you can read correctly is your visual acuity.

Part B: Taste

Taste Bud Map

Your tongue has taste buds for salty, sweet and sour foods in different areas. Follow the steps below to identify these areas.

  1. Obtain 2 cotton swabs for each person.
  2. Dip one swab into each solution. Place the moistened swab on your tongue in this order:
  3. Tip of tongue
  4. Side of tongue
  5. Middle of tongue
  6. Back of tongue
  7. Map your tongue on the Data Sheet.

Skittle Test

Have your partner close their eyes for all the steps below.

  1. Obtain a Skittle from your teacher.
  2. While your partner is sitting, have him/her close his/her eyes and hold his/her nose.
  3. Tell your partner to stick out his/her tongue.
  4. Place a Skittle on their tongue.
  5. Have your partner try to identify by taste alone the flavor you placed on their tongue.
  6. Repeat record the results.

Part C: Hearing

Observe how the distance of the origin of a sound in relation of your right and/or left ear helps to detect the direction of a sound.

1.Subject closes her/his eyes

2.The director hits the tuning fork in his/her hands to make a good vibration

3.The director places the tuning fork (while vibrating) at different distance in all directions from the subject (back, right, left and front).

4.The subject predicts position of tuning fork.

Explain to your group how you perceived the sound

Part D: Touch

Cotton Ball Test

Observe receptor accommodation.

1.Subject closes eyes

2.Director puts a cotton ball in the subject’s palm. Make sure subject feels it.

3.Subject says when the cotton ball is removed. (Stops perceiving cotton ball)

Precision Test

Use two-point discrimination to discuss size of receptor field in different parts of the body.

1.Subject closes eyes

2.Director, using the blunt needle, alternately marks one or two points with small and large distances on fingertips, palm and back of hand, lips and back of the subject.

3.Register response, noting if it was one or two points at a time

Field Sobriety Test

  1. Stand with your arms lifted to the sides.
  2. With the eyes closed, bend your elbows forward and try totouch your nose with your forefingers.
  3. Now repeat with your eyes opened.

Static Equilibrium

  1. Stand on one foot with your arms lifted to the sides.
  2. With the eyes closed, record how long you canmaintain your balance (up to a minute).
  3. Repeat with your eyes opened.

Proprioception

  1. Stand with your arms extended to the sides.
  2. With the eyes closed, swing your arms forward and bring all the fingertips together.
  3. Now repeat with your eyes opened.
    Both this and the proceeding tests demonstrate the role of vision in maintaining balance and determining position in space.