jspsych-webgazer-calibrate

This plugin can be used to calibrate the WebGazer extension. For a narrative description of eye tracking with jsPsych, see the eye tracking overview.

Parameters

In addition to the parameters available in all plugins, this plugin accepts the following parameters. Parameters with a default value of undefined must be specified. Other parameters can be left unspecified if the default value is acceptable.

Parameter	Type	Default Value	Description
calibration_points	array	`[[10,10], [10,50], [10,90], [50,10], [50,50], [50,90], [90,10], [90,50], [90,90]]`	Array of points in `[x,y]` coordinates. Specified as a percentage of the screen width and height, from the left and top edge. The default grid is 9 points.
calibration_mode	string	`'click'`	Can specify `click` to have subjects click on calibration points or `view` to have subjects passively watch calibration points.
repetitions_per_point	numeric	1	The number of times to repeat the sequence of calibration points.
randomize_calibration_order	bool	`false`	Whether to randomize the order of the calibration points.
time_to_saccade	numeric	1000	If `calibration_mode` is set to `view`, then this is the delay before calibrating after showing a point. Gives the participant time to fixate on the new target before assuming that the participant is looking at the target.
time_per_point	numeric	1000	If `calibration_mode` is set to `view`, then this is the length of time to show a point while calibrating. Note that if `click` calibration is used then the point will remain on the screen until clicked.

Data Generated

In addition to the default data collected by all plugins, this plugin collects the following data for each trial.

Name	Type	Value

No data currently added by this plugin. Use the webgazer-validate plugin to measure the precision and accuracy of calibration.

Example

Click-based calibration with 5 points

var calibration = {
    type: 'webgazer-calibrate',
    calibration_points: [[50,50], [25,25], [25,75], [75,25], [75,75]],
    repetitions_per_point: 2,
    randomize_calibration_order: true
  }

View-based calibration with 33 points, concentrated in the center

 var calibration = {
  type: 'webgazer-calibrate',
  calibration_points: [
    [10,10],[10,50],[10,90],
    [30,10],[30,50],[30,90],
    [40,10],[40,30],[40,40],[40,45],[40,50],[40,55],[40,60],[40,70],[40,90],
    [50,10],[50,30],[50,40],[50,45],[50,50],[50,55],[50,60],[50,70],[50,90],
    [60,10],[60,30],[60,40],[60,45],[60,50],[60,55],[60,60],[60,70],[60,90],
    [70,10],[70,50],[70,90],
    [90,10],[90,50],[90,90]
  ],
  repetitions_per_point: 1,
  randomize_calibration_order: true,
  calibration_mode: 'view',
  time_per_point: 500,
  time_to_saccade: 1000
}

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