Circular Fixation Point Stimulus

Description

An elliptical fixation point stimulus

Signature

stimulus/circular_fixation_point

Required Parameters

trigger_width

Width of the (circular) fixation window, which shares its center with the visible stimulus ellipse

trigger_watch_x

Variable containing the horizontal eye position

trigger_watch_y

Variable containing the vertical eye position

trigger_flag

Variable to which fixation status is written. When the subject’s gaze (as reported by trigger_watch_x and trigger_watch_y) enters the fixation window, the variable is set to true. When the subject’s gaze leaves the fixation window, the variable is set to false.

Optional Parameters

color

Default:1.0,1.0,1.0

The color of the stimulus, 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 stimulus. 1.0 is fully opaque, while 0.0 is fully tranparent.

x_size

Example:5.0

Horizontal size (degrees).

If omitted, the value of y_size is used. It is an error to omit both x_size and y_size (unless fullscreen is YES).

y_size

Example:5.0

Vertical size (degrees).

If omitted, the value of x_size is used. It is an error to omit both x_size and y_size (unless fullscreen is YES).

x_position

Default:0.0

Horizontal center position (degrees)

y_position

Default:0.0

Vertical center position (degrees)

rotation

Default:0.0

Rotation (degrees)

fullscreen

Default:NO

If YES, the stimulus is sized to fill the display. In this mode, x_size, y_size, x_position, y_position, and rotation are ignored.

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.