A circular checkerboard pattern. Includes options for scaling of radial check sizes (e.g. for cortical scaling), flicker, angular or radial phase drift, and internally balanced angular or radial phase drift. 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.

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

numRadialChecks is 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. Currently the dartboard is always centered at element position, with a boundary between checks along the right horizontal bisector. However, you can change element position in property position, and orientation about its center in property rotation.

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 intensity of dark and light checks.

Also set one of amplitude OR contrast:

amplitude is max intensity − mean intensity.

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

Intensity always clips at 0 and 1. It's possible to set a combination of these properties that causes the dartboard 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
angularTemporalFrequency
radialTemporalFrequency
angularTemporalFrequencyBalanced
radialTemporalFrequencyBalanced
fps

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

You can set one of the following:

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

angularTemporalFrequency is continuous phase drift rate in the angular dimension, i.e. rotation rate. This can be positive or negative to specify direction: + = clockwise, − = counterclockwise (angular cycles/sec). 0 = no phase drift.

radialTemporalFrequency is similar but in the radial direction, + = outward, − = inward (radial cycles/sec).

angularTemporalFrequencyBalanced is similar to angularTemporalFrequency except alternating rings of 1 check width rotate in opposite directions, creating an internally counterbalanced phase drift (angular cycles/sec). Here +/− just switches which rings move in which direction.

radialTemporalFrequencyBalanced is similar but in the radial direction, i.e. alternating wedges of 1 check width move in opposite directions (radial cycles/sec).

fps: If you set any of radialTemporalFrequency, angularTemporalFrequencyBalanced, radialTemporalFrequencyBalanced, 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

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