Source : Webster's Revised Unabridged Dictionary (1913)

Aftersensation \Aft"er*sen*sa`tion\, n. (Psychol.)
   A sensation or sense impression following the removal of a
   stimulus producing a primary sensation, and reproducing the
   primary sensation in positive, negative, or complementary
   form. The aftersensation may be continuous with the primary
   sensation or follow it after an interval.

Source : WordNet®

aftersensation
     n : an image (usually a negative image) that persists after
         stimulation has ceased [syn: {afterimage}]