<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
</head>
<body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">
Dear Joseph,
<div class=""><br class="">
</div>
<div class="">generally your trial length and your research question/post-processing. If you want to calculate event-related potentials you usually need 1000-500ms pre-stimulus baseline activity to extract the mean amplitude (which is then subtracted from post-stimulus
time points). Depending on the components you want to investigate, i.e. N200/P300, consequentially you will need at least 500ms post-stimulus, better 1000. A good start probably is -500 1000. </div>
<div class=""><br class="">
</div>
<div class="">For time-frequency transforms you will need longer epochs, because, depending on the wavelet starting frequency, a substantial amount of time points will be cut away both pre and post stimulus (this is due to the wavelets that take only the middle
time point). I.e. epochs from -1000 3000ms time-frequency transformed with a wavelet starting from 1Hz will leave you with data values from ca. -500 2500. So, be aware of that and go for longer epochs of you want to observe time-frequency activity. Some additional
thing: for time-frequency analyses you may (this is a later step in the analysis) indicate the baseline (if) to be subtracted from -800 to -200 or something like that, to avoid subtracting post-stimulus activity “smearing” into the baseline (due to the reason
mentioned above, especially relevant for low frequencies). </div>
<div class=""><br class="">
</div>
<div class="">For both approaches, if you have non-random stimulus overlap or responses leaking into the pre-stimulus period, its sometimes better to go for shorter pre-stimulus times.</div>
<div class=""><br class="">
</div>
<div class="">Hope this helps.</div>
<div class=""><br class="">
</div>
<div class="">Best, </div>
<div class="">Clemens</div>
<div class="">
<div style="color: rgb(0, 0, 0); letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">
<div class="" style="color: rgb(0, 0, 0); font-family: Helvetica; font-size: 16px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;">
<br class="">
</div>
<div class="" style="color: rgb(0, 0, 0); font-family: Helvetica; font-size: 16px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;">
<br class="">
</div>
<div class="" style="color: rgb(0, 0, 0); font-family: Helvetica; font-size: 16px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;">
<br class="">
</div>
<div class="" style="color: rgb(0, 0, 0); font-family: Helvetica; font-size: 16px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;">
<br class="">
</div>
</div>
</div>
<div style="">
<blockquote type="cite" class="">
<div class="">On 25 Jun 2016, at 22:06, Joseph Nuamah <<a href="mailto:jknuamah@aggies.ncat.edu" class="">jknuamah@aggies.ncat.edu</a>> wrote:</div>
<br class="Apple-interchange-newline">
<div class="">
<div dir="ltr" class="">
<div class="">
<div class="">
<div class="">
<div class="">Dear All,<br class="">
<br class="">
</div>
I am new to EEGLAB.<br class="">
<br class="">
</div>
My question is: what determines the choice of epoch length in EEGLAB.<br class="">
<br class="">
</div>
Thanks.<br class="">
<br class="">
</div>
Joseph.<br class="">
</div>
_______________________________________________<br class="">
Eeglablist page: <a href="http://sccn.ucsd.edu/eeglab/eeglabmail.html" class="">http://sccn.ucsd.edu/eeglab/eeglabmail.html</a><br class="">
To unsubscribe, send an empty email to <a href="mailto:eeglablist-unsubscribe@sccn.ucsd.edu" class="">
eeglablist-unsubscribe@sccn.ucsd.edu</a><br class="">
For digest mode, send an email with the subject "set digest mime" to <a href="mailto:eeglablist-request@sccn.ucsd.edu" class="">
eeglablist-request@sccn.ucsd.edu</a></div>
</blockquote>
</div>
<br class="">
</body>
</html>