Two triangle flash experiment

The experiment was to compare the visibilities of flashing lights having triangle temporal form: rising (upward triangles) or falling (downward triangles) lights. The experiment was limited to 0.4 sec duration, point source, foveal achromatic detection, in completely dark surround.  The ratio of the two visibilities was the experimental goal.  Five observers of very different visual capacities closely agreed on a ratio of about 1.00.