1. A computing device comprising: one or more processors; a memory coupled with the one or more processors; a login module operated by the one or more processors to authenticate a first user of the device and establish a first access control state corresponding to a first user profile associated with the first user and to authenticate a second user of the device and establish a second access control state corresponding to a second user profile associated with the second user; a contextual authentication module operated by the one or more processors to select between the first and second user profiles based at least in part on a changed user characteristic; a presentation module operated by the one or more processors to present a resource based at least in part on the second user profile; and a motion sensor, wherein the contextual authentication module comprises a profile selection module operated by the one or more processors to select between the first and second user profiles based at least in part on an output of the motion sensor and previously stored first and second templates generated by a machine learning classifier in association with the respective first and second users, and the profile selection module comprises a biometric machine learning classifier, wherein the profile selection module is to perform a biometric information classification of the output of the motion sensor and select between the first and second user profiles based at least in part on the biometric information classification and the previously stored first and second templates.