8.5 KiB
jsPsych.data
The jsPsych.data module contains functions for interacting with the data generated by jsPsych plugins.
jsPsych.data.addDataToLastTrial
jsPsych.data.addDataToLastTrial(data)
Parameters
| Parameter | Type | Description |
|---|---|---|
| data | object | Object of key: value pairs to add to the data from the last trial. |
Return value
Returns nothing.
Description
This method appends data to the data recorded by the last trial. It's particularly useful when combined with the on_finish event handler for a trial, as shown in the example below.
Examples
Evaluate a response and add to data
var block = {
type: 'single-stim',
stimuli: ['img/happy_face_1.jpg', 'img/sad_face_1.jpg'],
choices: [89,78], // Y or N
prompt: '<p class="center-content">Have you seen this face before? Y or N.</p>',
on_finish: function(trial_data){
// let's imagine that the correct answer is NO for both trials
var correct = (trial_data.key_press == 78);
jsPsych.data.addDataToLastTrial({correct: correct});
}
}
jsPsych.data.addProperties
jsPsych.data.addProperties(properties)
Parameters
| Parameter | Type | Description |
|---|---|---|
| properties | object | Object of key: value pairs to add to the data. |
Return value
Returns nothing.
Description
This method appends a set of properties to every trial in the data object, including trials that have already occurred and trials that have yet to occur. You can use this to record things like the subject ID or condition assignment.
Examples
Assigning a subject ID
jsPsych.data.addProperties({subject: 1});
jsPsych.init({
experiment_structure: exp
})
jsPsych.data.dataAsCSV
jsPsych.data.dataAsCSV()
Return value
Returns a string in CSV format
Description
Generate a CSV formatted string containing all of the data generated in the experiment.
Examples
Basic example
var csvString = jsPsych.data.dataAsCSV();
jsPsych.data.dataAsJSON
jsPsych.data.dataAsJSON()
Return value
Returns a string in JSON format
Description
Generate a JSON formatted string containing all of the data generated in the experiment.
Examples
Basic example
var jsonString = jsPsych.data.dataAsJSON();
jsPsych.data.displayData
jsPsych.data.displayData(format)
Parameters
| Parameter | Type | Description |
|---|---|---|
| format | string | Specifies whether to display the data in 'csv' or 'json' format. |
Return value
Returns nothing.
Description
Outputs all of the data collected in the experiment to the screen in either JSON or CSV format. This is a useful method for quick debugging when developing an experiment.
Examples
Using the on_finish callback function to show data at the end of the experiment
jsPsych.init({
experiment_structure: exp,
on_finish: function() {
jsPsych.data.displayData('csv');
}
})
jsPsych.data.getData
jsPsych.data.getData()
Parameters
None.
Return value
Returns an array containing all of the data generated in the experiment. Each element of the array contains the data for a single trial. Each trial's data is stored as an object in key: value format.
Description
Gets all of the data generated by the experiment.
Example
var alldata = jsPsych.data.getData();
jsPsych.data.getDataByTrialIndex
jsPsych.data.getDataByTrialIndex(trial_index)
Parameters
| Parameter | Type | Description |
|---|---|---|
| trial_index | numeric | The global trial index of the trial |
Return value
Returns an array containing all of the data for a particular trial. Trials are automatically indexed by a global
Description
Gets all the data generated from a specific trial.
Examples
Basic example
var first_trial_data = jsPsych.data.getDataByTrialIndex(0);
var second_trial_data = jsPsych.data.getDataByTrialIndex(1);
jsPsych.data.getLastChunkData
jsPsych.data.getLastChunkData()
Return value
Returns an array containing all of the data generated in the same chunk as the last trial. Each element of the array contains the data for a single trial. Each trial's data is stored as an object in key: value format.
Description
Gets all of the data generated in the same chunk as the last trial.
Example
var lastchunkdata = jsPsych.data.getLastChunkData();
jsPsych.data.getLastTrialData
jsPsych.data.getLastTrialData()
Return value
Returns an object in key: value format containing the data from the last trial.
Description
Gets the data generated by the last trial.
Example
var lasttrialdata = jsPsych.data.getLastTrialData();
jsPsych.data.getTrialsFromChunk
jsPsych.data.getTrialsFromChunk(chunk_id)
Parameters
| Parameter | Type | Description |
|---|---|---|
| chunk_id | string | The id of the chunk to get data from. |
Return value
Returns an array containing all of the data generated in a specified chunk. Each element of the array contains the data for a single trial. Each trial's data is stored as an object in key: value format.
Description
Get all the data generated by a specified chunk.
Example
var current_chunk_id = jsPsych.currentChunkID();
var data_from_current_chunk = jsPsych.data.getTrialsFromChunk(current_chunk_id);
jsPsych.data.getTrialsOfType
jsPsych.data.getTrialsOfType(type)
Parameters
| Parameter | Type | Description |
|---|---|---|
| type | string | Which plugin to get trial data from. |
Return value
Returns an array containing all of the data generated by a particular plugin. Each element of the array contains the data for a single trial. Each trial's data is stored as an object in key: value format.
Description
Gets all the data generated by trials from a particular plugin.
Examples
Basic example
var all_xab_trials = jsPsych.data.getTrialsOfType('xab');
Compute average RT over whole experiment
// this example shows how this method could be used to display data
// to the subject, by finding all trials of type 'single-stim' and
// calculating the average response time.
var debrief_block = {
type: "text",
text: function() {
return "<p>Your average response time was <strong>" +
getAverageResponseTime() + "ms</strong>. Press " +
"any key to complete the experiment. Thank you!</p>";
}
};
function getAverageResponseTime() {
var trials = jsPsych.data.getTrialsOfType('single-stim');
var sum_rt = 0;
var valid_trial_count = 0;
for (var i = 0; i < trials.length; i++) {
if (trials[i].rt > -1) {
sum_rt += trials[i].rt;
valid_trial_count++;
}
}
return Math.floor(sum_rt / valid_trial_count);
}
jsPsych.data.localSave
jsPsych.data.localSave(filename, format)
Parameters
| Parameter | Type | Description |
|---|---|---|
| filename | string | Filename of locally saved file |
| format | string | Specifies either 'csv' or 'json' format |
Return value
Returns nothing.
Description
Saves a CSV or JSON file on the computer running the experiment. If conducting an online experiment, this will download the file onto the subject's computer, and is therefore not a recommended data storage solution for online data collection.
Warning: This function relies on features which are currently not supported by all major web browsers, though adoption rates are increasing rapidly. It will work on the most recent versions of Chrome, Firefox, Safari, and Internet Explorer.
Example
jsPsych.data.localSave('mydata.csv', 'csv');
jsPsych.data.write
jsPsych.data.write(data_object)
Parameters
| Parameter | Type | Description |
|---|---|---|
| data_object | object | Object of key: value pairs to store in jsPsych's data storage as a trial. |
Return value
Returns nothing.
Description
This method is used by jsPsych.finishTrial for writing data. You should probably not use it to add data. Instead use jsPsych.data.addProperties.
Examples
// don't use this! data should only be written once per trial. use jsPsych.finishTrial to save data.
var trial_data = {
correct: true,
rt: 487
}
jsPsych.data.write(trial_data);