1. One or more non-transitory computer readable media having computer readable instructions stored thereon that when executed by a processor implement a method of user authentication at a computing device, the method comprising: displaying a plurality of objects on a display screen, the plurality of objects comprising objects that are part of a passcode, the passcode comprising a sequence of objects; for each object in the sequence of the passcode, receiving a trigger signal; in response to the trigger signal, causing an image sensor to capture an image; analysing the image to determine a direction of gaze; determining the object on the display screen that corresponds to the direction of gaze; determining whether the object that corresponds to the direction of the gaze matches the object in the sequence; and after the images have been analysed for all objects of the sequence, determining if a threshold for matches has been exceeded and if the threshold has been exceeded indicating positive authentication.