The perceptual "window" in two-handed braille: do the left and right hands process text simultaneously?

The hypothesis that fluent braille readers use both hands simultaneously to read was tested. Video tape recordings of finger movements by ten students reading prose text were subjected to frame by frame analyses of synchronous finger positions. The hypothesis was not borne out. Touching a letter by one hand was paired most often with simultaneous touching of a space between letters or between words by the other hand. Simultaneous touching of letters by the two hands was least frequent and did not differ from simultaneous touching of gaps between letters. Further evidence against the hypothesis came from analyses of the time relations between the two hands at the beginning and end of lines. It was argued that fluency does not depend on simultaneous processing of the same type of information, but on fast intermittent alternation in function between the two hands.