Responsepixx handheld

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).

Stimuli were presented on a 23-inch passive 3D monitor (D2367PH, AOC) that uses passive polarization with a spatial resolution of 1920 × 1080 pixels (52 cm × 29 cm) and a refresh rate of 60 Hz. Left and right images were separated by circular-polarization 3D glasses. Observers were seated at 90 cm from the monitor, so a pixel subtended 60.4 arcsec. To stabilize the observer’s head and to control the observation distance a chin rest (UHCOTech HeadSpot, Houston, TX) was used. In the 2AFC task (Experiment 1), subjects indicated their response by pressing the left or right button of a standard computer mouse. In the 4AFC tasks Experiment 2 & 3), subjects responded via a 4-button response box (ResponsePixx HandHeld, VPixx Technologies). The four corner buttons corresponded with the four spatial locations of the 4AFC (see Fig 2B). Data were collected on a DELL workstation (Intel(R) Core (TM) i3 CPU 540 @3.07GHz, 4GB RAM, 64- bit Operating System, Windows 7), with a GeForce GTX 460 graphics card (NVIDIA), running MATLAB R2012a, 64-bit (Mathworks). The experiments were programmed using Psychophysics Toolbox extensions [16 (link)–18 ].

In both experiments, the stimuli were presented on a gamma-corrected 19-in. Eizo Flex Scan T765 CRT monitor with a resolution of 1,024 × 768 pixels (horizontal × vertical) with a vertical frame rate of 120 Hz and mean luminance of 35.4 cd/m². The luminance of the monitor was corrected using a Minolta LS-110 photometer (Konica Minolta Optics, Inc., Osaka, Japan). The observation distance to the stimuli was 70 cm. A chin rest (UHCOTech HeadSpot, Houston, TX, USA) was used to control the observation distance and to stabilize the head of the participants. Responses were recorded using the ResponsePixx Handheld (VPixx Technologies, Inc., Saint-Bruno, Canada). A computer Mac Pro 3.7 GHz Quad-Core Intel Xeon E5 (graphics card AMD FirePro D300 2048 MB) was used to control the experiments. In Experiment 1, the participants observed the monitor through a mirror stereoscope constructed with two beam splitters and two mirrors (Elliot Scientific Ltd, Harpenden, UK). In Experiment 2, we used orthoptic eyepatches (Opticlude; 3M, New York, USA) to occlude one eye during the sessions.