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Yoko Mizokami, Michael A. Crognale; Detection of dual flashing lights. Journal of Vision 2005;5(8):766. doi: 10.1167/5.8.766.
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Flashing lights are often employed to increase visibility and safety. In the transportation industries and aviation there has been great effort invested in improving safety lights. Among the proposed design innovations is one in which lights appear to move (phi motion). There has been evidence that phi motion increases the salience of warning lights particularly for vehicle brake lights. Phi motion may also improve detection of warning lights at a greater distance such as with aircraft wingtip strobe lights. We tested the effect of phi motion on detection of small targets.
The intensity-thresholds of dual flashing lights were tested. A target with dual flashing lights was shown on a 1/f noise background generated on a 17 inch CRT monitor. The sizes of the target (distance of two lights) were over the range of 0.5 to 3 degree. The duration of light was 100 ms and different flicker rates were tested (10–20 Hz). The target was randomly presented in one of 4 quadrants, at 10 degree in the periphery. Subjects fixated a point on the center of monitor and judged in which quadrant the target appeared. A 4 AFC and two-staircase method was used to obtain thresholds. We compared in-phase flashing, out-of-phase flashing conditions and a steady lighting condition as a control.
Our results indicate that detection of dual flashing lights in the near periphery is not improved by a 180 degree temporal phase shift that induces phi motion over the range of conditions that we tested.
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