How to record multiple responses for a stimulus via "image-keyboard-response."

[K104Kaz]

Hi, experts.
I'm wandering that how can I get data for several response for a single image by using of "image-keyboard-response" plugin. When I set "response_ends_trial" parameter "false", the image remained but only the first response was recorded.
I think there is no parameter for this in the plugin, so perhaps I should modify the plugin file? I'm new to jsPsych and javascript. Any comments would be appreciated !

[becky-gilbert]

Hi @K104Kaz, yes I think you'll want to modify the plugin file to do this:

• In the jsPsych.pluginAPI.getKeyboardResponse function, change persist from false to true (false means that the keyboard listener should be cancelled after the first response).

var keyboardListener = jsPsych.pluginAPI.getKeyboardResponse({
  callback_function: after_response,
  valid_responses: trial.choices,
  rt_method: 'performance',
  persist: true,   // <- changed from false to true
  allow_held_key: false
});

• Change the responses object so that it stores arrays of rts and keys, instead of just one value for each:

// store response
var response = {
  rt: [], // <- changed from null to empty arrays, so that you can store multiple values
  key: []
};

• In the after_response function, remove the if statement that checks if response.key is null, and if so, stores the response. Instead, you want to add info.rt and info.key onto the responses.rt and responses.key arrays after every response:

response.rt.push(info.rt);   // <- these two lines instead of "if (response.key == null) {response = info;}"
response.key.push(info.key);

• In the end_trial function, when gathering the data in the trial_data object, use JSON.stringify to convert the rt and key arrays into JSON-formatted strings:

var trial_data = {
  "rt": JSON.stringify(response.rt), // <- add JSON.stringify
  "stimulus": trial.stimulus,
  "key_press": JSON.stringify(response.key) // <- add JSON.stringify
}; 

I hope this helps! Feel free to ask questions here and post your code if you get stuck.

[K104Kaz]

Thank you! It worked without a problem!

[rMinion]

@becky-gilbert In the example above Is it possible to get the value of the response key before ending the trial?

[becky-gilbert]

Hi @rMinion, I'm not entirely sure what you mean... It is possible to get the response key during the trial, after each response, from inside the plugin. Specifically, the callback_function (after_response in the example above) is called immediately after every key press - it receives an object containing the value of the key that was pressed and the RT. So you can use that information however you need to inside the after_response function.
But if you mean that you want to get the value of the key from outside of the plugin code (i.e. in your main experiment script) before the trial ends, I don't think that's easily done.

[xinyiguan]

I wonder if I can do the same (record multiple keyboard responses) for 1 stimuli via "audio-keyboard-responses."? I was trying to modified the audio-keyboard-responses plugin codes in a similar fashion. But I was not able to fully keep track and understand a few things. Specifically, I don't quite understand the following:

In the plugin-audio-keyboard-response.js script starting from line 165:

        const setup_keyboard_listener = () => {
            // start the response listener
            if (context !== null) {
                this.jsPsych.pluginAPI.getKeyboardResponse({
                    callback_function: after_response,
                    valid_responses: trial.choices,
                    rt_method: "audio",
                    persist: false,
                    allow_held_key: false,
                    audio_context: context,
                    audio_context_start_time: startTime,
                });
            }
            else {
                this.jsPsych.pluginAPI.getKeyboardResponse({
                    callback_function: after_response,
                    valid_responses: trial.choices,
                    rt_method: "performance",
                    persist: false,
                    allow_held_key: false,
                });
            }
        };

Can you elaborate a bit what rt_method means? What is the difference between "performance" and "audio"?

Would it be possible if you can walk me through the steps to modified the necessary part of the script to achieve my goal? Thanks!

BTW, I am using the 7.2 version

[jodeleeuw]

Hi @xinyiguan

Can you elaborate a bit what rt_method means? What is the difference between "performance" and "audio"?

The docs for the getKeyboardResponse method describe this a bit: https://www.jspsych.org/7.2/reference/jspsych-pluginAPI/#getkeyboardresponse.

Would it be possible if you can walk me through the steps to modified the necessary part of the script to achieve my goal? Thanks!

I think following the same steps described above by @becky-gilbert will work for the audio plugin too. The one change that you don't need to do the final one with JSON.stringify. Version 7.2 can handle arrays as the value for a data entry.

[phuongtran807]

Hi! I would like to make a similar alteration in my iat-html plugin. There is a function called 'force correct key response' when response.correct = false, so you have to press the right button in order to continue. In my case, I also want to record the second response time for pressing that button, so there are max. 2 values stored in the array.
I've tried it with the same instructions but there were several errors. For example did the blocks ended before every stimulus were presented and in general, the categorizations were off (i.e. the red x was presented even when pressing the right button). Also, in the final data all the trials were stored as correct (true).

Any help would be appreciated!

[matt-luke]

Much like @xinyiguan , I am trying to modify "audio-keyboard-responses" to accommodate multiple keypresses and their respective rt's. This time, in v8.1.0. I was wondering what I would have to do differently, due to the difference in the way the responses object is structured, as well as the after_response function. Thanks!