The invention relates to technologies for eye based biometric authentication. The invention provides methods, apparatuses and computer programs for initiating an action based on characteristics of acquired biometric information. In an embodiment, the invention comprises (i) receiving at least one image comprising an image of at least part of an eye, (ii) determining whether the at least part of an eye has birefringent characteristics, and (iii) initiating a predefined action responsive to (a) the at least part of an eye exhibiting birefringent characteristics that are inconsistent with a predefined set of birefringent characteristics or (b) a determined lack of birefringent characteristics typical of a real eye, wherein the predefined action comprises any one or more of denying biometric enrollment, denying biometric authentication, denying access to a resource, denying a request for unlocking of a resource, or transmitting or recording information identifying a spoof.
