Skin sensor experiment with hot and cold water

Materials Required

• Four bowls
• Cold water, Normal water (in room temperature) and hot water (heat that your hand can withstand)
• A Towel
• A couple of hands!

Procedure:

• Place the hot water bowl and the cold water bowl on the towels (towel is to avoid water spill)
• Fill the water only 3/4th of the bowl and that your palm would immerse.
• Fill the other 2 bowls with tap water and keep them aside.
• Now, get an assistant.
• Ask the person with his eyes blindfolded to place each of his hands – one in cold water and the other in hot water for 2 minutes.
• And ask the person which bowl is cold and which one is hot. Note down.
• Now ask him to lift his hands and replace the hot and cold water bowls with normal water bowls.
• Again ask the person to immerse his hand in normal water bowl. Of course without telling him the condition of the water in the bowls.
• Ask his which one is hot and which one is cold. He would reverse his first comments.

Inference

This is our brain playing trick on us. The sensors on our skin first recognizes the temperature of the cold and hot water correctly. Then when the same hands are placed in normal water –in one hand the normal water is colder than the previous hot water and on the other hand the normal water is hotter than the previous cold water – the sensors send different signals with reference to the previous water conditions and hence we feel different and both hands could not feel the normal water “normal”