Many mammals have whiskers but not all whisk. Cats don't. Rats do. To whisk, rats use special muscles in their face to brush their whiskers against an object. From the bending bristles, rats seem to be able to decode an object's shape and texture and Mitra Hartmann, engineer at Northwestern University, wants to understand how. This week, Hartmann and colleagues published a 3D whisker model, which she says will help quantify what information the brain receives from a whisk.