Moving Dots¶

Description¶

A moving dot field (aka dynamic random dots) stimulus

Signature¶

stimulus/moving_dots

Required Parameters¶

field_radius¶

Field radius (degrees)

dot_density¶

Number of dots per square degree

dot_size¶

Dot diameter (degrees)

speed¶

Dot speed (degrees per second)

Optional Parameters¶

field_center_x¶

Default: 0.0

Field horizontal center position (degrees)

field_center_y¶

Default: 0.0

Field vertical center position (degrees)

color¶

Default: 1.0,1.0,1.0

Dot color, expressed as a comma-separated list of red, green, and blue components. Each component may be described by any valid expression, but the expression must result in a value between 0 and 1 (inclusive).

alpha_multiplier¶

Default: 1.0

Controls the transparency of the dots. 1.0 is fully opaque, while 0.0 is fully tranparent.

direction¶

Default: 0.0

Direction of movement for coherent dots (degrees)

coherence¶

Default: 1.0

Fraction of dots that move in the specified direction. Non-coherent dots receive random directions.

lifetime¶

Default: 0.0

Dot lifetime (seconds). When a dot reaches the end of its lifetime, it is removed and replaced by a new dot in a random location.

If set to zero, dots have an infinite lifetime.

rand_seed¶

Seed value for the random number generator. If omitted, the current system time in nanoseconds is used.

max_num_dots¶

Maximum number of dots.

If omitted, the maximum number of dots is determined by the values of field_radius and dot_density when the stimulus is loaded.

announce_dots¶

Default: NO

If YES, stimulus announcements (i.e. #stimDisplayUpdate events) will include dot positions.

Position data is encoded as a binary array of single-precision floating point values (in platform byte order), with each consecutive pair of values representing the (x,y) coordinates of a dot. The coordinates are scaled to lie in the range [-1,1] and rotated so that the direction of coherent motion is zero degrees.

deferred¶

Options: no

yes

explicit
Default: no

Controls when the stimulus is loaded. If no, the stimulus is loaded at experiment load time. If yes, the stimulus is loaded the first time it is queued. If explicit, the stimulus must be loaded explictly with Load Stimulus.

autoplay¶

Default: NO

If YES, the stimulus will start playing automatically (as if by an implicit Play Dynamic Stimulus action) after it has been queued and Update Stimulus Display has been invoked. It will also stop playing automatically (as if by an implicit Stop Dynamic Stimulus action) after it has been dequeued and Update Stimulus Display is invoked.

Placement¶

Allowed at top level:	Yes
Allowed parent:	Folder, Frame List Stimulus, Layer Stimulus, List Replicator, Movie Stimulus, Range Replicator, Stimulus Group