“…Human motion perception indeed changes as light intensity decreases. Velocity perception (Gegenfurtner, Mayser, & Sharpe, 2000;Hammett, Champion, Thompson, & Morland, 2007;Pritchard & Hammett, 2012;Vaziri-Pashkam & Cavanagh, 2008), velocity discrimination thresholds (Takeuchi & De Valois, 2000), short-range motion perception (Dawson & Di Lollo, 1990), complex-motion perception (Billino, Bremmer, & Gegenfurtner, 2008), biological-motion perception (Billino et al, 2008;Grossman & Blake, 1999), perception of static-motion illusions (Hisakata & Murakami, 2008), perception of interstimulus interval (ISI) reversal (Sheliga, Chen, FitzGibbon, & Miles, 2006;Takeuchi & De Valois, 1997Takeuchi, De Valois, & Motoyoshi, 2001), perception of two-stroke motion (Challinor & Mather, 2010;Mather & Challinor, 2009), the coherent-motion threshold (Billino et al, 2008;Lankheet, van Doorn, & van de Grind, 2002;van de Grind, Koenderink, & van Doorn, 2000), moving texture segregation (Takeuchi, Yokosawa, & De Valois, 2004), and visual motion priming (Takeuchi, Tuladhar, & Yoshimoto, 2011;Yoshimoto & Takeuchi, 2013) have all been shown to vary with the light level.…”