Measuring the temporal contrast sensitivity function of the phantom array effect

The phantom array effect (PAE) has been widely investigated, but data are still insufficiently consistent to accurately predict the visibility of the PAE. One of the most critical steps towards a visibility measure is the temporal contrast threshold/sensitivity function. To determine this function, we experimentally measured the visibility threshold of the PAE at various frequencies. Participants were instructed to make 54.5° saccades in the dark across a thin light source, subtending a visual angle of 0.2° (horizontally) × 10° (vertically), with a luminance of 50 cd m −2 . Their task was to indicate in which of two sequentially presented stimuli they observed the PAE, where one stimulus was the reference driven with a direct current and one was the test stimulus, sinusoidally modulated over time. The QUEST+ method was used to change the modulation depth in the test stimulus. The results revealed a bandpass-shaped sensitivity curve of the PAE, with a peak at about 600 Hz. About 70% of the 22 participants had a peak sensitivity between a modulation depth of 0.04 and 0.13, and 65% of the 22 participants had a peak frequency between 460 Hz and 700 Hz.