A checkerboard pattern. Includes options for flicker, phase drift, and internally balanced phase drift. For checkerboard retinotopy using isolated bars see element type checkerboardRetinotopy.

No—runs until any condition you set in property end.

size

Default: square with sides 10 deg

A number that is side length for a square checkerboard, or a vector [width height] for a rectangle (deg).

numChecks

Default: 20 square checks across checkerboard width

Number of checks across the width of the checkerboard. Number of checks across its height is then automatic to give square checks.

Or a vector [n_w n_h] setting number of checks across width and height independently. You can use this if you want non-square checks.

orientation

Default: horizontal and vertical

Orientation angle of the checkerboard, + = clockwise (deg). 0 = horizontal and vertical rows/columns of checks. This sets rotation of the checkerboard within its rectangular display area. If you want rotation of the whole display, use property rotation.

phase

Default: first check right and below center is light

0/1 setting the initial pattern: 0 = first check right and below display center is dark, 1 = light. Currently the checkerboard is always centered at element position, with the corners of four checks at that point. Element position can be set in property position.

meanIntensity
amplitude
contrast

Defaults: meanIntensity = 0.5, amplitude = 0.5

meanIntensity is a number between 0–1 (black–maximum) setting the mean intensity of dark and light checks.

Also set one of amplitude OR contrast:

amplitude is intensity of light checks − intensity of dark checks.

contrast is Michelson contrast, amplitude / mean intensity. If you set contrast, mean intensity must be > 0.

Intensity always clips at 0 and 1. It's possible to set a combination of these properties that causes the checkerboard to clip in this way. See record properties maxAmplitude and maxContrast below.

color

Default: white <cd>[1 1 1]<cd>

A 1×3 RGB vector with numbers between 0–1. This defines the color at intensity = 1. Color at intensity = 0 is <cd>[0 0 0]<cd>. Color at intensities between 0–1 is linearly interpolated between the two. Note intensity, as defined by amplitude/contrast + meanIntensity above, always clips at 0 and 1, so color clips at <cd>[0 0 0]<cd> and color.

flickerFrequency
temporalFrequency
temporalFrequencyBalanced
fps

Defaults: no flicker or phase drift
Default: fps = 30 frames/sec

You can set one of flickerFrequency, temporalFrequency, OR temporalFrequencyBalanced:

flickerFrequency is frequency of switching between dark–light checks (cycles/sec). 0 = no flicker.

temporalFrequency is continuous phase drift rate. This is a 1×2 vector [v_x v_ y] specifying a rate for either horizontal or vertical drift (cycles/sec). You can only do horizontal OR vertical, so leave the other number at 0. The number you set can be positive or negative to specify direction: +/− = right/left or down/up (at orientation above = 0).

temporalFrequencyBalanced is similar except alternating rows or columns drift in opposite directions, creating an internally counterbalanced phase drift (cycles/sec). Here +/− just switches which rows/columns move in which direction.

fps: If you set temporalFrequencyBalanced, PsychBench implements the animation as a sequence of images showing at some frame rate (maximum). You can change that frame rate here if you want (frames/sec). Note this doesn't affect actual temporal frequency, just maybe the quality of the animation.

position
nn_eyes
rotation
colorMask
alpha
intensity
contrastMult
drawCodeVars

maxAmplitude
maxContrast

Maximum amplitude and contrast where intensity would clip at 0 or 1, whichever is reached first, given the set mean intensity.