jspsych-image-multi-response.md

jspsych-image-multi-response plugin

This plugin displays image content and records responses generated by both button click and the keyboard. Allowing multiple response modalities is useful when designing assessments that will be administered on both desktop and mobile (e.g., phone or tablet) devices. 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 participant has failed to respond within a fixed length of time.

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. Parameters can be left unspecified if the default value is acceptable.

Parameter	Type	Default Value	Description
stimulus	HTML string	undefined	The HTML content to be displayed.
button_choices	array of strings	[]	Labels for the buttons. Each different string in the array will generate a different button.
keyboard_choices	array of strings	"NO_KEYS"	This array contains the key(s) that the participant is allowed to press in order to respond to the stimulus. Keys should be specified as characters (e.g., 'a', 'q', ' ', 'Enter', 'ArrowDown') - see this page and this page (event.key column) for more examples. Any key presses that are not listed in the array will be ignored. Specifying "ALL_KEYS" means that all keys will be accepted as valid responses. The default value of "NO_KEYS" will mean that no responses are allowed.
button_html	function	(choice: string, choice_index: number) => `<button class="jspsych-btn">${choice}</button>;`	A function that generates the HTML for each button in the choices array. The function gets the string and index of the item in the choices array and should return valid HTML. If you want to use different markup for each button, you can do that by using a conditional on either parameter. The default parameter returns a button element with the text label of the choice.
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 participant is supposed to take (e.g., which key to press).
trial_duration	numeric	null	How long to wait for the participant to make a response before ending the trial in milliseconds. If the participant fails to make a response before this timer is reached, the participant'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.
stimulus_duration	numeric	null	How long to display the stimulus in milliseconds. The visibility CSS property of the stimulus will be set to hidden after this time has elapsed. If this is null, then the stimulus will remain visible until the trial ends.
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 participant 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 trial_duration is reached. You can set this parameter to false to force the participant 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
keyboard_response	string	Indicates which key the participant pressed. If the participant responded using button clicks, then this field will be null.
button_response	numeric	Indicates which button the participant pressed. The first button in the choices array is 0, the second is 1, and so on. If the participant responded using the keyboard, then this field will be null.
response_source	string	Indicates the source of the response. This will either be "button" or "keyboard".
rt	numeric	The response time in milliseconds for the participant to make a response. The time is measured from when the stimulus first appears on the screen until the participant's response.
stimulus	string	The HTML content that was displayed on the screen.

Example

var trial = {
  type: jsPsychHtmlMultiResponse,
  stimulus: '<p style="font-size:48px; color:green;">BLUE</p>',
  button_choices: ['Red', 'Green', 'Blue'],
  keyboard_choices: ['r', 'g', 'b'],
  prompt: "<p>Is the ink color (r)ed, (g)reen, or (b)lue?<br>Click the buttons or press the <kbd>r</kbd>, <kbd>g</kbd>, or <kbd>b</kbd> keys to respond.</p>"
};