Scot
It seems that I had two replies from you. Thanks very much. This
one, however, is far more interesting. Am I right in thinking that
your two main points here are a) The traditional notion of smooth
persuit is wrong headed because the eye anticipates the targets
heading rather than following it and b) maximum saccadic velocity
in natural reflex behaviour depends on the level of the observers
expertise.? If so, have you published this idea anywhere formally?
This corresponds to the way the data is looking in my current
research project.
Several replies have refered to WEsthiemers data but as yet I've
not been given a full reference.
Steve
> Westhieimers data is valid for untrained subjects tracking with the
> reauirement of maintenance of high resolution ability i.e tracking without
> overshoot or undershoot of fovea but this is not a valid value for more
> normal requirements of tracking to determine direction for interception or
> terminus information. Also quite small amounts of trianing make huge
> diferences in the peak track speed because much of the limitation is caused
> by natural reflex behaviour which abandons pursuit very early probably
> because the information gained by high speed smooth pursuit is rarely of
> much use. The eye tends to assess a trajectory and saccade to the terminus
> rather than pursue the entire trajectory. This early abandonment is easily
> overcome with training. It should be noted though that the eyes natural
> response to tracking trajectory is more accurate and effecient in terminus
> location than high speed pursuit as high pseed pursuit virtually eliminates
> stereo information cues.
>
> Scott Strachan
> ----- Original Message -----
> From: "J. W. Senders & A.C-Harris" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: 08 November 2000 15:27
> Subject: Re: smooth pursuit velocity thresholds
>
>
> > Steve Rogers,
> >
> > I suggest you start with
> >
> > Westheimer, G.H., "Eye Movement Responses to a Horizontally Moving
> > Stimulus" Archives of Ophthalmology, 1954, 52, p 932
> >
> > I believe that Westheimer's data show that 30 degrees per second is
> > about the maximum. An SCI search on this Westheimer paper should
> > reveal everything done since.
> >
> > John Senders
> >
> > >Can anybody direct me to research/papers that has tested for the
> > >maximum velocity that the eye can track a moving target (i.e. is
> > >there a velocity threshold where smooth persuit movements fail to
> > >keep up with a moving target?).
> > >
> > >Many thanks and best regards
> > >
> > >Steve Rogers
> >
> >
> >
> >
> > J.W. Senders, Professor Emeritus
> > Faculty of Applied Science
> > University of Toronto
> > 295 Indian Rd.
> > Toronto, Ont
> > M6R 2X5 Canada
> >
> > TEL: 416 769 5071
> > FAX: 416 769 6155
> > email [log in to unmask]
> >
>
Steve Rogers (BSc Hons, PGDip)
Centre for Ecological Psychology
Department of Psychology
University of Portsmouth
King Henry Building
Portsmouth
PO1 2DY
Tel: (01705) 846322
Fax: (01705) 846300
email: [log in to unmask]
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