Setting a minimum time at the trial level

[arthurprat]

In a html-keyboard-response trial, I would like to set a minimum duration (e.g., 1 second) before allowing my subjects to provide a response. The parameter minimum_valid_rt does this job but for the whole experiment (it's an argument to jsPsych.init), which is not what I want.

The parameters of an html-keyboard-response do not seem to do what I want (e.g., trial_duration sets the maximal duration if response_ends_trial is false, and it sets the maximal duration if response_ends_trial is true.)

Is there any straightforward way to do this? In #886 the following solution is given by @vijaymarupudi : make two trials, with the first one displayed for the duration I want and not accepting any response, and the second one recording a response. I am wondering if there is a better way.

[Shaobin-Jiang]

You can just:

• set the choices to something probably no one would have on their keyboard
• set up your own keyboard listener in on_load with a minimum_valid_rt
• feed the choices key in the callback

Example given below:

let jsPsych = initJsPsych();

let trial = {
    type: jsPsychHtmlKeyboardResponse,
    stimulus: 'Minimum rt: 3000 ms',
    choices: ['Symbol'],
    on_load: function () {
        jsPsych.pluginAPI.getKeyboardResponse({
            callback_function: function () {
                jsPsych.pluginAPI.keyDown('Symbol');
            },
            valid_responses: 'ALL_KEYS',
            minimum_valid_rt: 3000,
        });
    }
};

jsPsych.run([trial]);

You can, of course, use a much more secure way by setting choices to NO_KEYS and deal with keyboard responses entirely by yourself, but that would involve data recording as well, which is why I prefer the solution above.

[arthurprat]

Sorry I'm replying only now -- thank you for your great answer!