WordNet (r) 3.0 (2006):

unperceptive
    adj 1: lacking perception; "as unperceptive as a boulder" [syn:
           unperceptive, unperceiving] [ant: perceptive]
    2: lacking sensitivity, taste, or judgment

Moby Thesaurus II by Grady Ward, 1.0:

35 Moby Thesaurus words for "unperceptive":
   asleep, benumbed, blind, blindfold, blindfolded, callous, dead,
   deadened, dim-sighted, dull, impassible, imperceptive,
   impercipient, insensate, insensible, insensitive, insentient,
   mind-blind, myopic, nearsighted, nonunderstanding, numb, numbed,
   obdurate, obtuse, purblind, shortsighted, thick-skinned,
   thick-witted, unapprehending, uncomprehending, undiscerning,
   unfeeling, unfelt, unperceiving