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sine_grid

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Summary

This stimulus consists of a grid of drifting sinewave patches. It is designed to emulate the pseudoplaid stimulus of Kumbhani, El-Shamayleh and Movshon (2015, J Neurophys). The demonstration here is done as a binocular stimulus, with opposite motion across eyes, but Kumbhani's stimulus was monocular, which can be achieved by setting the stim_monocular parameter to "left".

Sine gratings at two orientations are displayed in alternating patchdes. The grid size and scale of the patches can be varied to assess pattern motion integration.

This stimulus is a variation of the gabor_grid stimulus type - please see documentation for gabor_grid for a full description of parameters.

Examples

• sine_grid_4x4.stm - 2017 May 3 - Movie (.mov) - A 4 by 4 grid of sine patches.

Imperfections

None reported.

Parameters

• grid_type - 'regular' - this type of grid consists of Gabor patches that are alternate orientation across neighboring locations.

• patch_type - 'sine' - this parameter causes the patches to be sine gratings rather than 'gabor' functions, the latter being the default for this (gabor_grid) stimulus type.

• size - (deg) patch diameter. Typically, this would be made equal to 'box_w' and 'box_h' (see documentation for gabor_grid).

• taper_len - (deg) this defines the length of the outer region of the grating patch over which contrast will be tapered to zero. Kumbhani set this to be 25% of the patch radius, which would be 1/8th of 'size' here.

• For other parameters, see gabor_grid documentation.

General stimulus control

• stim_monocular ['both'] or 'left' or 'right'. This is a general stimulus parameter that defaults to the value, both, but can be set to either left or right to blank out the other eye's image, which is set to the background value. For example, when set to left, the left eye image is displayed normally while the right eye image is replaced with the background value, typically mean gray.

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