jspsych-categorize-image

The categorize image plugin shows an image object on the screen. The subject responds by pressing a key. Feedback indicating the correctness of the response is given.

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 to the image file.
key_answer numeric undefined The numeric key code indicating the correct response.
choices array of keycodes jsPsych.ALL_KEYS This array contains the keys that the subject is allowed to press in order to respond to the stimulus. Keys can be specified as their numeric key code or as characters (e.g., 'a', 'q'). The default value of jsPsych.ALL_KEYS means that all keys will be accepted as valid responses. Specifying jsPsych.NO_KEYS will mean that no responses are allowed.
text_answer string "" A label that is associated with the correct answer. Used in conjunction with the correct_text and incorrect_text parameters.
correct_text string "Correct." String to show when the correct answer is given. Can contain HTML formatting. The special string %ANS% can be used within the string. If present, the plugin will put the text_answer for the trial in place of the %ANS% string (see example below).
incorrect_text string "Wrong." String to show when the wrong answer is given. Can contain HTML formatting. The special string %ANS% can be used within the string. If present, the plugin will put the text_answer for the trial in place of the %ANS% string (see example below).
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).
force_correct_button_press boolean false If set to true, then the subject must press the correct response key after feedback is given in order to advance to the next trial.
show_stim_with_feedback boolean true If set to true, then the stimulus will be shown during feedback. If false, then only the text feedback will display during feedback.
show_feedback_on_timeout boolean false If true, then category feedback will be displayed for an incorrect response after a timeout (timing_response is exceeded). If false, then a timeout message will be shown.
timeout_message string "Please respond faster." The message to show on a timeout non-response.
stimulus_duration numeric null How long to show the stimulus for (milliseconds). If null, then the stimulus is shown until a response is given.
feedback_duration numeric 2000 How long to show the feedback for (milliseconds).
trial_duration numeric null The maximum time allowed for a response. If null, then the experiment will wait indefinitely for a response.

Data Generated

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

Name Type Value
stimulus string Either the path to the image file or the string containing the HTML formatted content that the subject saw on this trial.
key_press numeric Indicates which key the subject pressed. The value is the numeric key code corresponding to the subject's response.
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.
correct boolean true if the subject got the correct answer, false otherwise.

Examples

Categorizing an image

var categorization_trial = {
    type: 'categorize-image',
    stimulus: 'img/harrypotter.png',
    key_answer: 71,
    text_answer: 'Gryffindor',
    choices: [71, 72, 82, 83],
    correct_text: "<p class='prompt'>Correct! This person is a %ANS%.</p>",
    incorrect_text: "<p class='prompt'>Incorrect. This person is a %ANS%.</p>",
    prompt: "<p>Is this person a (G)ryffindor, (H)ufflepuff, (R)avenclaw, or (S)lytherin?</p>"
};