iPad experiments for toddlers

(Update 3/24/15 – this post is subsumed by a paper we wrote on this topic, available here).
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The iPad should be a fabulous experimental tool for collecting data with young children: It's easy to use, kids love it, and it's even cheaper and easier to transport than a small Mac laptop. Despite these advantages, there has been one big drawback: creating iPad apps requires mastering a framework and programming language that are specific to iOS, and putting the apps on more than a few iPads requires dealing with the app store. Neither of these are impossible hurdles, but both of them have kept us (and AFAIK most other labs in developmental psychology) from getting very far in using them for routine day-to-day data collection.

This post documents a new method that we have been using to collect experimental data with toddlers, developed this summer by Elise Sugarman, Dan Yurovsky, and Molly Lewis. It is easy to use, makes use of free development tools, doesn't require dealing with the App Store or the Apple Developer Tools, and hooks in nicely with the infrastructure we use to create Amazon Mechanical Turk web experiments for adults.

Our method has four ingredients:

1. JavaScript/HTML web experiment
2. Server-side PHP script to save data
3. iPad with internet connection, in kiosk mode
4. Kid management on the iPad

1. JavaScript/HTML web experiment. 

This is the big one for someone who has never made an online experiment. It's beyond the scope of this post to introduce how to create JavaScript web experiments, but there is a lot of good material out there, especially from the Gureckis Lab at NYU (e.g. this blog post). There are also many tools for learning how to make websites using the now standard combo of JavaScript, HTML, CSS, and jQuery. Note that putting up such an experiment will require some server space. We use the space provided by Stanford for our standard university web pages, but all that's required is somewhere to put your HTML, JS, and CSS files.

2. PHP script 

This is a simple script that runs on a server (probably the same one that you are using to serve the experiment). All it does is save data from the JavaScript experiment to a location on the server. 

In the JavaScript code, we need to add a bit of code to send the data to this script (making sure jQuery is loaded so we can use ".post"):

  

if (counter === numTrials) {

     $.post("http://lab.example.edu/cgi-bin/expt_dir/post_results.php", 
         {postresult_string : result_string});

}

And then post_results.php is a simple script that looks like this:

<?php

    $result_string = $_POST['postresult_string'];

    file_put_contents('results.csv', 

        $result_string, FILE_APPEND);

?>

3. iPad config 

Our method requires that you have an internet connection handy for your iPad. This means that you either need wifi access (e.g. from the testing location or a MiFi) or else you need an iPad with cell connectivity. But aside from that, you're just navigating the iPad to a website you've set up.

We use two tools to ensure that iPad-savvy kids don't accidentally escape from our experiment or zoom the screen into something totally un-navigable. The first is Guided Access, a mode on the iPad that disables the hardware buttons. The second is Mobile Kiosk, an app that further locks the iPad into a particular view of a webpage. The combination means that kids can't get themselves tangled in the functionality of the iPad.

4. Kid management

The last ingredient is training kids to use the iPad effectively. Although many of them will have interacted with tablet devices and smartphones before, that's no guarantee that they can tap effectively and navigate through an experiment. We created a simple page training with a set of dots for a child to tap - they can't advance until they successfully tap all the dots (kind of like Whac-A-Mole).

(Update #1: Elise notes that using a tilting iPad case helps kids click more successfully as well.)

(Update #2: Brock Ferguson gives a handy guide to making the PHP above more secure if you ever want to use it for anything other than preschoolers.)