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| * [[http://www.hlp.rochester.edu/mturk/mtadapt/expt_demo.html|Phonetic perception/adaptation]] | * [[http://www.hlp.rochester.edu/mturk/mtadapt-demo/expt_vroomen_replication.html?condition=ambig|Phonetic perception/adaptation]] |
Amazon Mechanical Turk
Relevant Papers
Conducting behavioral research on Amazon’s Mechanical Turk by Winter Mason & Siddharth Suri should be a standard reading for anyone conducting mturk experiments in the lab.
Example MTurk Experiments
Self paced reading (run with modified IBex)
- an example of spoken recording as soon as we have it
Standard Practices
Consent form blurb (always make sure it links to the current version of the consent form):
<div id="consent">
By accepting this HIT, you confirm that you have read and understood the
<a target="_blank" href="http://www.hlp.rochester.edu/consent/English_2013-05-13.pdf">consent form</a>,
that you are willing to participate in this experiment, and that you
agree that the data you provide by participating can be used in
scientific publications (no identifying information will be used).
Sometimes it is necessary to share the data elicited from you
— including sound files — with other researchers for scientific
purposes (for replication purposes). That is the only reason for
which we will share data and we will only share data with other
researchers and only if it is for non-commercial use. Identifying
information will <span style="font-weight:bold;">never</span> be shared (your MTurk ID will be replaced
with an arbitrary alphanumeric code).
</div>
Always include the following text near where you link to the consent form:
<p>Sometimes it can happen that technical difficulties cause experimental scripts to freeze so that you will not be able to submit a HIT. We are trying our best to avoid these problems. Should they nevertheless occur, we urge you to contact us.</p>
Also include this blurb (including the link to the blog):
<p>If you are interested in hearing how the experiments you are participating in help us to understand the human brain, feel free to subscribe to our <a href="http://hlplab.wordpress.com/">lab blog</a> on which we announce new findings. Note that typically about one year passes before an experiment is published.</p>
If you are recording audio from the workers include this blurb:
<p>You must be a native speaker of American English. If you have not spent almost all of your time until the age of 10 in the United States, you cannot participate. If you have a non-American accent we will not be able to pay you. For example, British or Indian English is not permissible for this experiment.</p>
Please use this example as a template for your own instructions page.
Remember also that we may only recruit US workers. This is a University of Rochester policy. By default Amazon lets you recruit from all regions, which in practice means you will get a lot of Indians (2nd largest worker area after the US).
Always include this qualification in your properties file if you do external HITs (changing all of the 2s to the appropriate number based on how many other qualifications you have):
# this is a built-in qualification -- user must be in the United States qualification.2:00000000000000000071 qualification.comparator.2:equalto qualification.locale.2:US qualification.private.2:true
If you use the web based interface, when you click "Design", then go to the first tab "Enter Properties" under "Additional Qualifications" be sure to add Location is UNITED STATES.
Tips
Audio
If you intend to play audio, keep in mind that not all browsers support the same formats within the <audio> tag. Make sure to provide multiple <source> tags within your <audio> block, in the order you'd prefer the browser choose them, e.g.
<audio>
<source src="foo.m4a" type="audio/mp4" />
<source src="foo.ogg" type="audio/ogg" />
<source src="foo.mp3" type="audio/mpeg" />
<source src="foo.wav" type="audio/wav" />
Your browser does not support the audio element.
</audio>
Use as many or few as you need to get full coverage, or at least coverage for all the browsers you care about.
Here is a table of current levels of support in the major browsers:
|
m4a |
mp3 |
ogg |
wav |
IE9 |
no |
yes |
no |
no |
Opera 11 |
no |
no |
yes |
yes |
Firefox 13 |
no |
no |
yes |
yes |
Chrome 20 |
yes |
yes |
yes |
yes |
Safari 5.1 |
yes |
yes |
no |
yes |
To convert a wav to mp3:
lame --resample 22.05 -b 64 foo.wav foo.mp3
To convert a wav to m4a:
ffmpeg -y -i foo.wav -acodec libfaac -ab 64k foo.m4a
To convert a wav to ogg:
ffmpeg -i foo.wav -acodec libvorbis -ab 64k foo.ogg
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