Science project

Primary Sensory Cortex

(30 ratings )


  • 9 toothpicks
  • Metric ruler
  • Tape
  • Blindfold (optional)
  • Partner

Experimental Procedure

  1. Place the ruler on the table.
  2. Lay 3 toothpicks side-by-side on one end of the ruler. The toothpicks should be touching each other. Now tape them in this position. Record the distance between the toothpicks in Table 1 under "Position 1".
  3. Choose 3 more toothpicks and place them on the other end of the ruler. This time space them a little further apart, but space them evenly. Tape them into position. Record the distance between the toothpicks in Table 1 under "Position 2."
  4. Choose 3 more toothpicks and place them in the center of the ruler. This time space them a littler further apart (the widest spacing). Tape them into position and record the distance in Table 1 under "Position 3."
  5. With your partner's eyes closed and their hand laid on a table, gently touch the tip of their dominant index finger with the tip of two toothpicks at position 1. Ask your partner how many tips they felt. Record in Table 1.
  6. Repeat step 5 using two toothpick tips at positions 2 and 3.
  7. Repeat steps 6 and 7 using three toothpick tips.
  8. Repeat steps 5, 6, and 7 using the inside of your partner's forearm instead of their index finger.
  9. Was your partner's finger or forearm more sensitive to the touch of the toothpicks?
  10. Which area of the body, finger or forearm, has more space reserved for its use in the primary sensory cortex? Explain.

Table 1

Toothpick Position Index Finger Forearm

Position 1

Distance between

toothpicks _______cm

Tips used Tips sensed Tips used Tips sensed
2 2
3 3

Position 2

Distance between

toothpicks _______cm

2 2
3 3

Position 3

Distance between

toothpicks _______cm

2 2
3 3

Terms/Concepts: Cerebrum; Primary sensory cortex


Author: Angela Pike
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