2Further Reading: Chapman EK et al. (1989) Look and Think: Visual Perception Training for Visually Impaired Children (5-11 years). Royal National Institute for the Blind, London.
if p > p (where p implies
if q > p (for q to exist; ie the next level up, then so too must p, eg; Attending needs Awareness
if not p > not q (if p does not exist then neither does q, nor those levels above).