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. This element type also includes two animation options commonly used in retinotopy tasks:

(1) wedges: show a sequence of isolated wedges by stepping an aperture angularly around the dartboard
(2) rings: show a sequence of isolated rings by stepping an aperture radially through the dartboard

For just a static dartboard or with flicker or phase drift only, see element type dartboard. See also checkerboardRetinotopy.

"Ends on its own" means ends automatically at that point. If an element can end on its own, you don't need to set end conditions for it in property end (unless you want it to maybe end earlier).

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).

You can combine using these properties with wedge/ring apertures below. (Note those are different/independent wedges and rings to the ones referred to here—those ones can have any width and spacing, whereas the ones here are just wedges and rings within the dartboard pattern, one check wide and evenly spaced.)

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.

showWedges
showRings
apertureSize
apertureStep
apertureInterval
aperturePhase
maxNumLoops

Default: showWedges, showRings = don't show wedges or rings—show whole dartboard
Default: apertureSize = 2 checks
Default: apertureStep = 1 check moving clockwise or outward
Default: apertureInterval = 1 sec
Default: aperturePhase = 0 checks
Default: maxNumLoops = show one pass through the dartboard

You can set one of showBars or showRings = <cd>true<cd> to show a sequence of isolated wedges by stepping an aperture angularly around the dartboard, or rings by stepping an aperture radially through the dartboard. If you do:

apertureSize is wedge or ring width (angular or radial checks).

apertureStep is how far the wedge or ring moves at each step (angular or radial checks). +/− determines direction of movement: +/− = clockwise/counterclockwise or outward/inward.

apertureInterval is time between steps (sec).

aperturePhase is for wedges only. It sets the initial wedge shown. It is a number of angular checks, + = clockwise. What zero means depends on apertureStep: 0 = first wedge below the right horizontal bisector if apertureStep ≥ 0 (moving clockwise), or first wedge above if apertureStep < 0 (moving counterclockwise). You can also change orientation of the whole display about its center in property rotation.

For rings, initial ring is always the innermost ring if ringVelocity ≥ 0 (moving outward), or the outermost ring if ringVelocity < 0 (moving inward).

maxNumLoops is a number > 0 that is number of passes through the dartboard to show, after which the object ends. <cd>inf<cd> = repeat until a condition you set in property end.

Note these numbers can be fractional, not just integer.

Note for rings if you set radialScale above to unequal radial check sizes, the aperture changes size and step size in terms of distance on screen as it moves, corresponding to varying check size.

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.