Fixation Point Stimulus

Description

A rectangluar fixation point stimulus

Signature

stimulus/fixation_point

Required Parameters

trigger_width

Width of the (square) fixation window, which shares its center with the visible stimulus rectangle

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.

x_size

Example:5.0

Horizontal size (degrees)

y_size

Example:5.0

Vertical size (degrees)

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 with values between 0 and 1 (inclusive). The list can include variable names in place of explicit values, in which case the corresponding component value will be read from the named variable.

x_position

Default:0.0

Horizontal center position (degrees)

y_position

Default:0.0

Vertical center position (degrees)

rotation

Default:0.0

Rotation (degrees)

alpha_multiplier

Default:1.0

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

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.