A computer-implemented method, for verifying an electronic device user, comprising the steps of issuing at least one action instruction to an electronic device user using a notification mechanism of the electronic device; recording response data from a plurality of data acquisition systems of the electronic device, the response data pertaining to the user's response to the at least one action instruction; processing the response data to form classification scores; combining the classification scores to form a classification value; and verifying the user if the classification value satisfies a threshold, wherein each of the at least one action instruction comprises a liveness challenge.