jatso study and browser type

m.vel

Hi All,

I have two studies that combines components of JsPsych and OSWeb on Jatos. This is a linear study that allows reload.

The study generally works, but I have a participant that tried both studies and each time something went wrong. I tired the study immediately after with the same link and it all worked fine. So I want to ask, does JATOS have different browser compatibilities? I use Chrome, but what if the participant uses another browser on which JATOS is less stable? Is that even possible? I am just wondering how the same person can have a fail with two different, but equally set up, studies.

Thanks,

Marta

elisa

Hi Marta,

In general, it can be pretty hard to diagnose problems on participants' side (the client-side) because you don't know what really happened, unless they share e.g. a screenshot of their browser and console. If you know the participant, it's always helpful to ask them to do that.

The browser is definitely a possible reason. Different browsers do differ in whether they have implemented different functions, and also how tolerant they are on missing semicolons etc. I don't think that compatibility between a browser and JATOS is the reason, because the functions used in JATOS are generally implemented in all browsers. On the other hand, I see your point: if it failed with both an OSWeb study and a jsPsych study, JATOS seems to be a more likely explanation.

It is good practice, and should be standard, to (1) check that your study runs on all browsers and (2) restrict your study to run only in those browsers that you checked.

You could use something like this to ensure that people can only run your study in Chrome.

function checkBrowser() {
    var browserInfo = getBrowserInfo();
    switch (browserInfo.browser) {
        case "Chrome":
            break;
        default:
            document.write('<center><br/><p class="instructions">This experiment only supports Google Chrome</p>' // or Mozilla Firefox.
                + '<p class="instructions">Please reopen the experiment in Chrome.</p>');
            break;
    };
};

function getBrowserInfo() {
        var ua = navigator.userAgent, tem,
            M = ua.match(/(opera|chrome|safari|firefox|msie|trident(?=\/))\/?\s*(\d+)/i) || [];
        if (/trident/i.test(M[1])) {
            tem = /\brv[ :]+(\d+)/g.exec(ua) || [];
            return 'IE ' + (tem[1] || '');
        }
        if (M[1] === 'Chrome') {
            tem = ua.match(/\b(OPR|Edge)\/(\d+)/);
            if (tem != null) return tem.slice(1).join(' ').replace('OPR', 'Opera');
        }
        M = M[2] ? [M[1], M[2]] : [navigator.appName, navigator.appVersion, '-?'];
        if ((tem = ua.match(/version\/(\d+)/i)) != null)
            M.splice(1, 1, tem[1]);
        return { 'browser': M[0], 'version': M[1] };
    };

Hope this helps

Elisa

m.vel

Hi Elisa,

Thank you for your answer.

The study has components in JsPsych and OSWeb, but it failed both times in the OSWeb component. And it is true, I am not sure what happened because the definition I got was "stopped working". I did ask some follow up questions, because I have a linear study, so if they tried to go back, it would fail. When I find out which browser was used, I will test it on that.

I do not have any error messages in my JATSO log, and the study results as not finished yet.

The study seems to otherwise be working as I am getting results in.

Marta

elisa

Ah, I see. I misunderstood. Then it is likely an OSWeb issue. In the JATOS log you'll find any errors related to data transfer to/from the server. If you don't see anything suspicious there, it's likely a JavaScript problem that doesn't get logged on JATOS, because it belongs to the client side.

When/if you have more information, post a question in the OSWeb forum.

kri

Hi Marta,

You could also try to catch errors in your participant's browsers and write them into the JATOS log. Just put

jatos.catchAndLogErrors();

somewhere in the beginning of your JavaScript, e.g. in jatos.onload. Maybe there is an error that helps identifying the problem. But this works only since JATOS 3.5.6. And I'd recommend to turn it on only during piloting since it can flood your JATOS log if there are many participants with many errors.

Best,

Kristian

m.vel

Hi again,

The participant apparently used Chrome, which is what I used to set up the task. The task includes images and audio, and it is on the heavy side. But apparently what happened is that the images disappeared completely and the audio kept going.

Does anyone know how this is possible?

kri

Sounds more like an OSWeb or browser issue - not so much JATOS.