 The phenomenon of blindsight, a form of unconscious visual perception that arises with damage to specific areas of primary visual cortex, has also been investigated in surgically lesioned monkeys (Stoerig &amp; Cowey 1997), with a close correspondence between the monkeys' deficits and those of the human patients vis-à-vis parts of the visual field that can be processed only unconsciously, and those for which the patients retain consciousness. The non-verbal approach to assessing visual awareness has been further validated by Stoerig et al. (2002).  Blindsight subjects, both human and monkey, do not spontaneously respond to things presented to their scotomas (areas where they are visually unaware), but must be trained to make responses using a forced-response paradigm (Stoerig &amp; Cowey 1997). 