Datapixx lite

We used the same equipment for both the motion and the spatial experiments. All stimuli were presented on a gamma-corrected 17-in Eizo Flex Scan T565 CRT monitor under the control of a Mac Pro 3.7 GHz Quad-Core Intel Xeon E5 (graphics card AMD FirePro D300 2048 MB) running Matlab (The MathWorks, Inc, Natick, MA) using the Psychophysics Toolbox extensions [62 (link)–64 (link)] with 14-bits of gray-scale resolution (DataPixx Lite, VPixx Technologies Inc., Canada, http://www.vpixx.com). The luminance was corrected using a Minolta LS-110 photometer (Konica Minolta Optics, Inc., Osaka, Japan). The monitor had a resolution of 800 × 600 pixels (horizontal × vertical) with a vertical frame rate of 148 Hz, mean luminance of 49.1 cd/m², and was observed binocularly from a distance of 55 cm in a dark room. A chin rest (UHCOTech HeadSpot, Houston, TX) was used to stabilize the head of the participants and to control the observation distance. Responses were recorded using the ResponsePixx Handheld (VPixx Technologies Inc., Canada).

Participants viewed stimuli on a 19″ Eizo T765 CRT monitor from a distance of 100 cm. The monitor had a resolution of 1280×1024 pixels, 14-bit luminance levels and subtended a visual angle of 19.18×15.37 degrees at the viewing distance of participants. Its mean luminance was 57 cd/m². Luminance was gamma corrected (gamma=2.31) using a Minolta LS-100 (Konica Minolta, Tokyo, Japan). A chin-rest (UHCOTech HeadSpot, University of Houston College of Optometry, Houston, USA) was used to stabilise the subject's head. Experiments were administered by a Matlab script using Psychophysics Toolbox Version 3 (PTB-3) (Brainard, 1997 (link); Pelli and Brainard, 1997 (link); Kleiner et al., 2007 ). DataPixx Lite and ResponsePixx Handheld devices (VPixx Technologies, Saint-Bruno, Canada) were used to render stimuli and capture participant responses.