Perceptual learning has also been invoked in possible adaptation of normal observers to the inevitable image degradation by their ocu-lar aberrations (Artal et al., 2004). Recent advances in adaptive op-tics techniques have enabled their cancellation with consequent improvement in visual acuity. Careful probing has revealed little if any perceptual adaptation to this long-standing image degrada-tion (Rossi et al., 2007; Rossi & Roorda, 2010). The topic of percep-tual learning with subsequent improvement in an observer’s