Abstract: A non-obtrusive portable device, wearable from infancy through adulthood, mounted with i) a set of two or more optical device(s) providing visual and audio information as perceived by the user; ii) an actuated mirror or optical device returning visual information on part of the face of the user. The audio-visual signals may be processed on-board or off-board via either hardwired or wireless transmission. Analysis of audio visual signal permit among other things tracking of the user's gaze or facial features and of visual and auditory attention to external stimuli.