Dear Oleg and Gustav,
there are in fact a number of deviations to saccades that may occur in ordinary data, including "rest" periods in the middle of the saccade. http://www.humlab.lu.se/www-transfer/tmp/Paulina3822f.png is a x, y and velocity plot from a reading study we made. This particular participant, a normal young student, exhibited a large number of broken saccades like this. We have confirmed that this is not slippage in data, but exactly what it is? Just poor muscle control? Wong (2008) and Cuiffreda and Tannen (1995) describe a large number of deviating saccades, linking them to neurological disorders and damages, but none that look as extreme as these.
Oleg: We are also developing improved event detection algorithms in our lab; for instance Nyström, M. & Holmqvist, K., (2010) "An Adaptive Algorithm for Fixation, Saccade, and Glissade Detection in Eye-Tracking Data", Behavior Research Methods. Vol. 42(1) pp. 188 - 204
best regards,
/ Kenneth
------------------------------------------------
Assoc. Prof. Kenneth Holmqvist
Tech. Director of the Humanities Lab
Lund University
PO Box 201
221 00 Lund
Sweden
email: [log in to unmask]
http://www.humlab.lu.se/en/home
Tel. +46-46-222 0934
Lab. +46-46-222 3214
------------------------------------------------
On 3 sep 2010, at 18.13, Gustaf wrote:
> Dear Oleg,
>
> It could be a number of things going on, but it is close to impossible to make an informed guess without knowing more about the onset, the vertical component and, last but not least, prior stimuli.
>
> To me the trace looks like a subject expecting a stimuli at one position and then correcting very transiently, but it is hard to tell without knowing more about the recording.
>
>
> Best regards,
>
> Gustaf Öqvist Seimyr
> The Bernadotte Laboratories
> St. Erik Eye Hospital
> Karolinska Institutet
>
>
>
>
> 3 sep 2010 kl. 17:24 skrev "Komogortsev, Oleg V" <[log in to unmask]>:
>
>> Hello everybody,
>>
>> In our lab we are trying to develop reliable algorithms for classification of complex oculomotor behavior, with some details described in http://ecommons.txstate.edu/cscitrep/18/
>> Recently we have acquired EyeLink II and we are trying to classify some of the oculomotor events that became visible when recording is conducted at the frequency of 1000Hz or higher.
>> We are presenting horizontal step stimulus to the subject.
>>
>>
>> We have encountered an event where a saccade to a target is slightly broken in the middle, the event does not look like an express saccade, i.e. there is not enough latency in the between the pieces. The picture of the event is present here http://daizanxun.blog.com/files/2010/09/eye-movement.jpg
>>
>>
>> My question what is it?
>>
>> May be it is equipment slippage? Or maybe saccade trajectory change during some sort of the neuronal control noise during saccade's pulse?
>> I was not been able to find an example of this type of behavior in the research literature and I was hoping that somebody would be able to point me to the correct source.
>>
>> Thank you in advance.
>>
>> ---Oleg
>>
>> ---
>> Dr. Oleg Komogortsev
>> Assistant Professor
>> Texas State University-San Marcos
>> Department of Computer Science
>> 601 University Drive
>> San Marcos, TX 78666-4616
>> Phone: (512) 245-0349 Fax: (512) 245-8750
>> Email: [log in to unmask]<mailto:[log in to unmask]>
>> Webpage: www.cs.txstate.edu/~ok11<http://www.cs.txstate.edu/~ok11>
>>
>>
>> --
>> EYE-MOVEMENT mailing list ([log in to unmask])
>> N.B. Replies are sent to the list, not the sender
>> To unsubscribe, etc. see http://www.jiscmail.ac.uk/files/eye-movement/introduction.html
>> Other queries to list owner at [log in to unmask]
>
> --
> EYE-MOVEMENT mailing list ([log in to unmask])
> N.B. Replies are sent to the list, not the sender
> To unsubscribe, etc. see http://www.jiscmail.ac.uk/files/eye-movement/introduction.html
> Other queries to list owner at [log in to unmask]
--
EYE-MOVEMENT mailing list ([log in to unmask])
N.B. Replies are sent to the list, not the sender
To unsubscribe, etc. see http://www.jiscmail.ac.uk/files/eye-movement/introduction.html
Other queries to list owner at [log in to unmask]
|