In this activity, students discover how the physical distribution of sensory receptors in our bodies can create a tactile illusion.
Sensory receptors are not distributed evenly across our bodies. Some parts of our body, like our fingertips, are very densely packed with nerve endings and touch receptors. They are highly sensitive to touch, and can differentiate between even very fine, minute touch sensations. Other parts of our body, like our forearms, are less packed with touch receptors, so they are not as good at sensory discrimination. If you move from an area of higher sensory discrimination to a lower one, you can experience something very odd – two distinct sensations can suddenly feel like just one!