jsPsych/docs/markdown_docs/plugins/jspsych-free-sort.md

jspsych-free-sort plugin

The free-sort plugin displays a collection of images on the screen that the subject can interact with by clicking and dragging. All of the moves that the subject performs are recorded.

Parameters

This table lists the parameters associated with this plugin. 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
stimuli	array	undefined	Each element of this array is also an array. The innermost arrays contain a set of image paths (strings) to show as a group. Each innermost array represents a single trial. The length of the outer array determines the number of trials in the block.
stim_height	numeric	100	The height of the images in pixels.
stim_width	numeric	100	The width of the images in pixels.
sort_area_height	numeric	800	The height of the container that subjects can move the stimuli in. Stimuli will be constrained to this area.
sort_area_width	numeric	800	The width of the container that subjects can move the stimuli in. Stimuli will be constrained to this area.
prompt	string	""	This string can contain HTML markup. The intention is that it can be used to provide a reminder about the action the subject is supposed to take (e.g. which key to press).
prompt_location	string	"above"	Indicates whether to show the prompt "above" or "below" the sorting area.

Data Generated

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

Name	Type	Value
init_locations	JSON string	A JSON-encoded object representing the initial locations of all the stimuli in the sorting area. The object is an array with one element per stimulus. Each element in the array has a "src", "x", and "y" value. "src" is the image path, and "x" and "y" are the object location.
moves	JSON string	A JSON-encoded object representing all of the moves the participant made when sorting. The object is an array with each element representing a move. Each element in the array has a "src", "x", and "y" value. "src" is the image path, and "x" and "y" are the object location after the move.
final_locations	JSON string	A JSON-encoded object representing the final locations of all the stimuli in the sorting area. The object is an array with one element per stimulus. Each element in the array has a "src", "x", and "y" value. "src" is the image path, and "x" and "y" are the object location.
rt	numeric	The response time in milliseconds for the subject to finish all sorting.

Examples

Basic example

// declare an array to hold the stimuli
var sorting_stimuli = [];
for (var i = 1; i <= 12; i++) {
    sorting_stimuli.push("img/cell_img_" + i + ".jpg");
}

// create free-sort block for jspsych
var sort_block = {
    type: 'free-sort',
    stimuli: [sorting_stimuli],
    prompt: "<p>Click and drag the images below to sort them so that similar items are close together.</p>"
};