RIDE magazine did a thorough test of helmets including a "spike in the helmet" test.
www.ridetriangles.com/pdf/643/221609.pdf (6 Mb)

That's fine if you have a Shoei shaped head. Mine's Arai shaped.....

(not that I'm complaining! )

I've an Arai, used to have a Shoei, both good helmets.

Standard test is as they would be expected to perform in a typical m/c accident ie vertical drop about 5 feet.

That's all.

The Arai's have a much much stiffer area in the region below ears whereas most others can be squshed together.

ATB

Simon