The challenge
Ask a partner to lightly touch your back with either 1 finger or 2 fingers held close together — without telling you which. Eyes closed. Try to identify whether it is 1 touch or 2 across 10 attempts. Track your score.
Objective
Experience the variation in tactile receptor density across different body regions.
Materials
A partner and 2 fingers.
Description
This experiment demonstrates two-point discrimination — the minimum distance at which two separate touches can be perceived as distinct. The fingertips can distinguish points 2–3 mm apart. The back requires 4–7 cm. This variation reflects the density of Meissner's corpuscles and Merkel's discs in each region. The body map in your brain is not proportional — areas with more sensation have disproportionately large representation.