Note that this reference documentation is identical to the help that is displayed in MATLAB when you type “help bcifun_latidx”.

  BCIFUN_LATIDX extracts alpha power, computes the alpha lateralization index 
  and sends a command to an external device
 
  This function computes the lateralization index log(A/B) for the
  average alpha power in right channels A and the average alpha power
  in left channels B. In a covert attention experiment we expect
  higher values for attention to the right visual hemifield and lower
  values for attention to the left visual hemifield.