The MERL system uses 3D face models and specifically targets illumination and pose variation, which they think as the most critical factors limiting performance.
It is caused in part by prolonged hyperglycemia (high blood sugar) and results in dysfunction of one or both tibial nerves and a plantigrade stance (down on the hocks).
Two other poses were tried and I emerged from the booth to find photos of me as Indiana Jones, a fireman from Backdraft and a wrestler being strangled in a headlock.