Experimental design (after ). Mah-Jong or Braille tile patterns were presented manually. During tactile matching, the subjects closed their eyes and a block of two joined tiles was placed in their right palm for them to feel with their right thumb. If the patterns were the same, the correct response was "yes", and subjects pressed a button with their left index finger. If the patterns were different, subjects signaled "no" by pressing a different button with the left middle finger.