The phantom array experiment at the CSTB feat. Xiangzhen Kong and Anders Thorseth, supervised by Christophe Martinsons during the MetTLM project.

<p>This video shows the phantom array experiment carried out at the CSTB in Grenoble, France,&nbsp; featuring Xiangzhen Kong (the experimenter) and Anders Thorseth (the test subject), supervised by Christophe Martinsons (CSTB researcher) during the EMPIR MetTLM project funded by EURAMET.</p> <p>This experiment was designed to measure the sensitivity of people to the phantom array effect. The phantom array effect is a undesirable visual effect caused by temporal light modulation (TLM) occuring when high modulation frequencies are present in the light source while the observer moves their eyes. It is more visible in the dark than in bright ambient conditions. The highest visibility happens at around 600 Hz (peak of the sensitivity curve) but the phenomenon is visible from 80 Hz up to several kHz depending on the visual acuity of the observer.</p> <p>In this experiment, the light source was a fine slit. Its modulation frequency was slowed down to a few hertz in order to be seen easily on the video. The observer had to move their eyes back and forth between fixed points. Two sucessive stimuli were presented in a random order, a modulated stimulus and a steady-state stimulus (no TLM). The protocol was based on randomized, counterbalanced, repeated measures using a two-interval forced choice (2IFC) procedure optimized with an adaptive procedure called QUEST+ developed by Andrew Watson for psychovisual experiments.&nbsp;</p> <p>The experiment used an eye-tracing device to monitor the saccade speed and amplitude during the experiment.</p>