Effects of temporal variation of auxiliary light stimuli upon detectability of tonal signals

Literature is surveyed briefly which reported the effect upon hearing of varying the onset of a light relative to the onset of a tone. Four forced-choice experiments involving approximately 32,000 trials of the four-alternative type are reported whose results show both similarities and differences when compared with earlier experiments which did not use forced-choice. Tentative conclusions derived from all the experiments described also take into account the effect of cessation of the light relative to the tone.