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54 lines
3.5 KiB
Markdown
54 lines
3.5 KiB
Markdown
# jspsych-image-keyboard-response
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This plugin displays and image and records responses generated with the keyboard.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.
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## Parameters
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Parameters with a default value of undefined must be specified. Other parameters can be left unspecified if the default value is acceptable.
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Parameter | Type | Default Value | Description
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----------|------|---------------|------------
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stimulus | string | *undefined* | The path of the image file to be displayed.
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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](http://www.cambiaresearch.com/articles/15/javascript-char-codes-key-codes) 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.
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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).
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stimulus_duration | numeric | null | How long to show the stimulus for in milliseconds. If the value is -1, then the stimulus will be shown until the subject makes a response.
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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 -1 for the trial and the trial will end. If the value of this parameter is -1, then the trial will wait for a response indefinitely.
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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 `timing_response` parameter). If false, then the trial will continue until the value for `trial_duration` 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.
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## Data Generated
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In addition to the [default data collected by all plugins](overview#datacollectedbyplugins), this plugin collects the following data for each trial.
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Name | Type | Value
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-----|------|------
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key_press | numeric | Indicates which key the subject pressed. The value is the [numeric key code](http://www.cambiaresearch.com/articles/15/javascript-char-codes-key-codes) corresponding to the subject's response.
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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.
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stimulus | string | The path of the image that was displayed.
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## Examples
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#### Displaying trial until subject gives a response
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```javascript
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var trial = {
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type: 'image-keyboard-response',
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stimulus: 'img/happy_face_1.png',
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choices: ['e', 'i'],
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prompt: "<p>Is this person happy or sad? Press 'e' for happy and 'i' for sad.</p>",
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response_ends_trial: false
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};
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```
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#### Displaying image for a fixed duration; no response allowed
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```javascript
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var trial = {
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type: 'image-button-response',
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stimulus: 'img/happy_face_1.png',
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choices: jsPsych.NO_KEYS,
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prompt: "<p>Study this face for 5 seconds.</p>",
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trial_duration: 5000
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};
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```
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