An electronic device is able to alter one or more settings of its imager based on the motion of a user that the device is attempting to authenticate. The electronic device, in one implementation, captures a first set of image data of the user (e.g., a video or still photo of the user), detects motion of the user, alters a setting of the imager based on the motion, captures a second set of image data of the user, and authenticates the user based on the second set of image data. In some implementations, the electronic device has multiple imagers, and activates one or more additional imagers based on the detected motion of the user.