jsPsych/docs/plugins/jspsych-image-button-response.md

jspsych-image-button-response

This plugin displays an image and records responses generated with a button click. The stimulus can be displayed until a response is given, or for a pre-determined amount of time. The trial can be ended automatically if the subject has failed to respond within a fixed length of time. The button itself can be customized using HTML formatting.

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
stimulus	string	undefined	The path of the image file to be displayed.
choices	array of strings	[]	Labels for the buttons. Each different string in the array will generate a different button.
button_html	HTML string	'<button class="jspsych-btn">%choice%</button>'	A template of HTML for generating the button elements. You can override this to create customized buttons of various kinds. The string %choice% will be changed to the corresponding element of the choices array. You may also specify an array of strings, if you need different HTML to render for each button. If you do specify an array, the choices array and this array must have the same length. The HTML from position 0 in the button_html array will be used to create the button for element 0 in the choices array, and so on.
prompt	string	null	This string can contain HTML markup. Any content here will be displayed below the stimulus. 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).
stimulus_duration	numeric	null	How long to show the stimulus for in milliseconds. If the value is null, then the stimulus will be shown until the subject makes a response.
trial_duration	numeric	null	How long to wait for the subject to make a response before ending the trial in milliseconds. If the subject fails to make a response before this timer is reached, the subject's response will be recorded as null for the trial and the trial will end. If the value of this parameter is null, the trial will wait for a response indefinitely.
margin_vertical	string	'0px'	Vertical margin of the button(s).
margin_horizontal	string	'8px'	Horizontal margin of the button(s).
response_ends_trial	boolean	true	If true, then the trial will end whenever the subject makes a response (assuming they make their response before the cutoff specified by the trial_duration parameter). If false, then the trial will continue until the value for timing_response is reached. You can use this parameter to force the subject to view a stimulus for a fixed amount of time, even if they respond before the time is complete.

Data Generated

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

Name	Type	Value
rt	numeric	The response time in milliseconds for the subject to make a response. The time is measured from when the stimulus first appears on the screen until the subject's response.
button_pressed	numeric	Indicates which button the subject pressed. The first button in the choices array is 0, the second is 1, and so on.
stimulus	string	The path of the image that was displayed.

Examples

Displaying question until subject gives a response

var trial = {
	type: 'image-button-response',
	stimulus: 'img/happy_face_1.png',
	choices: ['Happy', 'Sad'],
	prompt: "<p>Is this person happy or sad?</p>"
};