Read Blindsight by Peter Watts. Apart from being an incredible novel it gets into this question, and it's freely available from the author's site: http://www.rifters.com/real/Blindsight.htm

Trying to avoid spoilers here, so ROT13 - Gur nyvraf rapbhagrerq va gur abiry ner abg pbafpvbhf, naq uhzna pbafpvbhfarff vf cerfragrq nf na ribyhgvbanel fvqr rssrpg / zvfgnxr juvpu erdhverf hf gb jnfgr uhtr nzbhagf bs cbjre guvaxvat nobhg guvaxvat, vafgrnq bs whfg guvaxvat. Bhe phygher, oebnqpnfg vagb fcnpr, nccrnef yvxr n QQBF nggnpx bs vafnar vachgf gb gur aba-pbafpvbhf nyvraf orpnhfr bs ubj zhpu rssbeg vg gnxrf gb cnefr guebhtu vg nyy.

(The neurological phenomena of blindsight is also very very interesting, and suggests that our brains may do more work than is strictly required)