@article{ref1,
title="Vigilance effects for duration judgments with two levels of task demand",
journal="Perceptual and motor skills",
year="1972",
author="Hawkes, G. R. and Sherman, Steven J.",
volume="34",
number="2",
pages="351-356",
abstract="<p>[Abstract unavailable]</p><p>Language: en</p>",
language="en",
issn="0031-5125",
doi="",
url="http://dx.doi.org/"
}