Off All the Nerve

To discover which parts of the body are more sensitive to touch than other parts of the body

• 2 sharpened pencils
• Tape
• Blindfold

The human body is full of nerve endings. Some parts of the body have fewer nerve endings than other parts making them less sensitive to touch. Arms for example are one of the body parts with fewer nerve endings.

In this investigation, areas on the arm are tested for sensitivity.

Terms, Concepts, and Questions to Start Background Research

sensitive: easily affected by touch

stimuli: something that causes sensitivity

receptors: a part of the body that receives and responds to stimuli

The skin is full of nerve endings. Some places on the skin are more sensitive to touch than other parts.

Research Questions

• Why are some areas on the body more sensitive to touch?
• What parts of the body are more sensitive to touch? What parts are less sensitive?

1. Gather the necessary materials.
2. Tape the two pencils together. Be sure that the sharpened ends are even and will touch a flat surface at the same time.
3. Choose 10 subjects. Don’t let any of the subjects see the pencils. Tell them that you will gently touch them with either one or two pencils.
4. Blindfold one of the subjects. Gently touch the subject with the pencils on the upper arm. Ask the subject how many pencils he or she feels. Record the response.
5. Next, gently touch the subject with the pencils on the lower arm. Ask the subject how many pencils he or she feels. Record the response.
6. Finally, touch the subject with the pencils on the index finger. Ask the subject how many pencils he or she feels. Record the response.
7. Repeat Steps 4 – 6 with each of the subjects.

The Brain and Senses at http://www.childrensuniversity.manchester.ac.uk/interactives/brainandsenses/sensitivity.asp