A circular checkerboard pattern. Properties set options for size, pattern, scaling of radial check sizes (e.g. for cortical scaling), amplitude/contrast, and color, as well as an option for flicker. You can also show solid concentric rings if you set number of angular checks = 1.

For dartboard retinotopy using isolated wedges or rings, see element type dartboardRetinotopy. For fixation see element types dots, cross, fixationGrid, etc.

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

diameter          
centerDiameter

Default: diameter = 10 deg
Default: centerDiameter = 0.2 deg

diameter is diameter of the dartboard (deg).

centerDiameter is diameter of the center area, which is transparent (deg).

numAngularChecks
numRadialChecks

Default: numAngularChecks = 20
Default: numRadialChecks = 8

numAngularChecks is integer number of segments (light or dark) around the dartboard at any radius.

numRadialChecks is integer number of segments in any radial line, from edge of the transparent center area to outer edge of the dartboard.

e.g. numAngularChecks = 4, numRadialChecks = 1 → a dartboard consisting of four segments in quadrants.

radialScale

Default: equal radial check sizes

You can use this property to apply cortical (or other) scale factors to check sizes in the radial direction. This is a vector of numbers > 0 that are radial check sizes, from innermost to outermost. Number of sizes must = numRadialChecks above. The absolute magnitudes of the sizes don't matter, only their magnitudes relative to each other. Actual radial sizes are automatically scaled to fit numRadialChecks into the radius from edge of the transparent center area to outer edge of the dartboard.

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. Note currently the dartboard is always centered at element position, with a boundary between checks along the right horizontal bisector. Element position can be set in property position.

meanIntensity
amplitude
contrast

Defaults: mean intensity = 0.5, amplitude = 0.5 → black & maximum intensity

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

Also set one of:

amplitude is max intensity − mean intensity.

OR

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

It's possible to set a combination of these properties that causes the dartboard to clip at intensity 0 or 1. See record properties maxAmplitude and maxContrast below.

color

Default: white

A 1×3 RGB vector with numbers between 0–1. This defines color at pixel intensity = 1. Color at intensity = 0 is <cd>[0 0 0]<cd> (black).

flickerFrequency

Default: no flicker

Frequency of switching between dark–light (cycles/sec). 0 = no flicker.

position
nn_eyes
rotation
colorMask
alpha
intensity
contrastMult
drawCodeVars

maxAmplitude
maxContrast

Values for input properties amplitude and contrast that would cause intensity to clip at 0 or 1 given the current value of meanIntensity.