a computing system comprising a processor and a memory storing computer program instructions executable by the processor;

a head-mounted device configured to reproduce video signals received from the computing system;

one or more orientation sensors configured to measure an orientation of the head mounted device when mounted on the subject; and

one or more physiological sensors to measure one or more physiological parameters of the subject, the physiological parameters selected from the group consisting of respiratory rate, heart rate, and perspiration;

wherein the computer program instructions comprise functionality to:

substantially continuously receive from the one or more orientation sensors the orientation of the head mounted device of the subject,

substantially continuously determine the video signals including one or more avatars in a virtual reality scenario to be displayed on the head mounted device taking into account the received orientation of the head mounted device, wherein the virtual reality scenario provides the subject with a feeling of being physically or perceptually within an environment,

send the video signals to the head mounted device for visualization, and

adapt the virtual reality scenario to expose the subject to the fear by gradually transforming one or more of the avatars from a first state to a second state, the second state of the one or more avatars to provoke an increase of anxiety related to the fear, the increase of anxiety being reflected by an output of the one or more physiological sensors, to expose the subject to an increased level of fear,

wherein the virtual reality scenario further comprises a central focus point aimed at attracting a center of gaze from the subject, wherein the central focus point is a central avatar talking to the subject,

and wherein the computer program instructions further comprise functionality to:

split the central avatar into a plurality of avatars,

move one or more of the plurality of avatars to a peripheral field of vision,

and wherein the transforming one or more of the avatars from a first state to a second state takes place responsive to the following:

a predetermined amount of time from a previous increase of anxiety related to the fear, as indicated by an output of the one or more physiological sensors, has passed, and

the one or more of the avatars are in a peripheral field of vision of the subject as derived from the orientation of the head mounted device;

such that, responsive to passage of the predetermined amount of time, and responsive to the subject not looking at the one or more avatars moved to the peripheral field of vision, at least one of the one or more avatars transforms from the first state to the second state;

wherein repeated passage of the predetermined amount of time and transformation of additional ones of the one or more avatars from the first state to the second state exposes the subject to a gradually increased level of fear without necessarily provoking an increase in anxiety of the subject.