[Lewis Thomson (OP)]

Listener Marian submitted this head-scratcher to The Naked Scientists.

"Why is it that when I scratch, the itch seems to move around so that I end up scratching in more places?"

What findings have your found? Leave your answers in the comments below...

[vhfpmr]

I have no answer, but I get what I might describe as "referred itching". I sometimes feel an itch in a different place to the location that's causing it, in the same way as referred pain is felt in a different place to the cause (eg: arm pain from a heart attack). The itch itself doesn't move, but I have to search around to find the right place to scratch it.

[Colin2B]

"Why is it that when I scratch, the itch seems to move around so that I end up scratching in more places?"

The difficulty of precisely locating a specific point on the back is due to its lower density of skin nerve fibres. The density is much higher in hands, arms, legs where  what is called 2-point location is more important.
Can be frustrating when asked to scratch a partner’s back to be told “no, up a bit, no left, down! ....”