Sense of touch.
One molecule thick difference between two surfaces.
Difference between Wood and Metal sense is because metal draws heat away from your hand faster than wood, which is why metal feels colder even if it’s the same temperature according to another instrument.
So: Maybe to figure out how my hand knows different metals, is looking at the rate these materials draw head away – their heat sink capability.
BUT beyond that: what this is showing is that the vibration characteristics are different even at one molecule thing. Too thin to be a heat sink.