Wait until correct key is pressed

[Quinlanptq]

I am a bit stuck. I want to present a stimulus and record every key press and its RT until the correct key is pressed.

So stim on, start clock, then record every key and RT. The last record will be when the correct key is pressed.

Any advice gratefully received,
Thanks
Philip.

[jodeleeuw]

Hi Philip,

You'll need to modify a plugin to do this. html-keyboard-response is probably the right starting point.

You can set the persist parameter to true on the getKeyboardResponse() method. This will allow you to gather more than one response.

jsPsych/plugins/jspsych-html-keyboard-response.js

Lines 123 to 128 in 6bcb624

	var keyboardListener = jsPsych.pluginAPI.getKeyboardResponse({
	callback_function: after_response,
	valid_responses: trial.choices,
	rt_method: 'performance',
	persist: false,
	allow_held_key: false

Every time a response is made it calls this function

jsPsych/plugins/jspsych-html-keyboard-response.js

Lines 105 to 119 in 6bcb624

	var after_response = function(info) {
	// after a valid response, the stimulus will have the CSS class 'responded'
	// which can be used to provide visual feedback that a response was recorded
	display_element.querySelector('#jspsych-html-keyboard-response-stimulus').className += ' responded';
	// only record the first response
	if (response.key == null) {
	response = info;
	}
	if (trial.response_ends_trial) {
	end_trial();
	}
	};

You'll want to edit this so that info.key and info.rt are stored for each key press. I'd suggest creating an array for each and pushing the values onto the array. Then you can add the arrays to the trial data about here:

jsPsych/plugins/jspsych-html-keyboard-response.js

Lines 90 to 95 in 6bcb624

	// gather the data to store for the trial
	var trial_data = {
	"rt": response.rt,
	"stimulus": trial.stimulus,
	"key_press": response.key
	};

For consistency with other plugins, you'll want to use JSON.stringify() to convert the arrays to their JSON string representation before saving them in the data.

[Quinlanptq]

As ever, really helpful Josh thanks Philip.