Interactive user authentication

A computer-implemented method for verifying an electronic device user, the method comprising the steps of:

• issuing at least one action instruction comprising a liveness challenge 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, including identifying, from the response data, the likelihood of at least one characteristic pattern associated with an action instruction, comprising:
• processing video data to assess a classification score of at least one characteristic motion associated with the action instruction by:
• performing a plurality of head pose estimations on the video data,
• processing the plurality of head pose estimations to form extracted pose information, including:
• extracting a series of angles from the plurality of head pose estimations;
• fitting a function to the series of angles;
• constructing a feature vector from parameters of the function, the fitting of the function, and the head pose estimations;
• and testing if the video data contains at least one characteristic motion with the feature vector, and
• forming a facial action classification score using the extracted pose information;
• combining the classification scores to form a classification value;
• and
• verifying the user when the classification value satisfies a threshold.