A mask consisting of dots moving with random linear motion on a transparent background. Various masks are possible ranging from direction coherence masks to more completely randomized masks. Dots move in straight lines with initial positions, directions, speeds, ages, and lifetimes randomized for each dot. If a dot reaches the edge of the mask area it wraps around to the opposite side. If a dot reaches the end of its lifetime it disappears and reappears with new random position, velocity, and lifetime (and age 0).
Note that since masks are randomized and have a transparent background you can layer multiple masks on top of each other if you need one mask that has a mix of properties.
At default settings transparency artifacts may be visible at dot edges, mostly if dots overlap. These are minimal and usually insignificant. If you need to avoid them, you can set property backColor = <cds>"opaque"<cds>. However, the element background will then not be transparent.
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).
No—runs until a condition you set in property end.
You can vary or allow the subject to adjust the following input properties of an object of this type in real time when it's running. If you need to make other properties adjustable, you can edit the element type code—see Element Type Programming Manual.
Default: square with sides 15 deg
A number that is side length for a square mask area, or a vector [width height] for a rectangle (deg).
Number of dots. Can = 0.
Default: <cd>[0 180]<cd> = dots move in random directions
Dot motion direction clockwise, 0 = right (deg). Or a vector [direction, delta] setting direction ± delta to randomize for each dot.
Default: <cd>[2 1]<cd> = dots move randomized between 1–3 deg/sec
Dot speed (deg/sec). Or a vector [speed, delta] setting speed ± delta to randomize for each dot.
Default: <cd>[1.5 0.5]<cd> = dots last randomized between 1–2 sec
Dot lifetime (sec). <cd>inf<cd> = no limit. Or a vector [lifetime, delta] setting lifetime ± delta to randomize for each dot.
Default: 0.2 deg
Dot diameter (deg).
A 1×3 RGB vector with numbers between 0–1.
PsychBench uses record properties to record information during experiments. You can't set record properties but you can see them in experiment results by listing them input property report.