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 subject has failed to respond within a fixed length of time.
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 subject 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 | 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). |
| 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. |
| 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 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 trial_duration is reached. You can set this parameter to false to force the subject to view a stimulus for a fixed amount of time, even if they respond before the time is complete. |
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 subject pressed. If the subject responded using button clicks, then this field will be null. |
| button_response | numeric | Indicates which button the subject pressed. The first button in the choices array is 0, the second is 1, and so on. If the subject 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 subject to make a response. The time is measured from when the stimulus first appears on the screen until the subject's response. |
| stimulus | string | The HTML content that was displayed on the screen. |
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>"
};