Elling Prediction in Ocular Pursuit
It has been realised since the early work of Dallos and Jones (1963) that predictive behaviour must be present in human ocular pursuit for three main reasons: (1) performance is better in response to predictable periodic target motion than it is to more random stimuli; (2) when pursuing sinusoids, phase errors at frequencies above 0.5Hz are much less than would be expected from the time delay (100ms) in visual feedback (Carl and Gellman 1987); (3) in a linear velocity error feedback system a combination of high gain and a large time delay would lead to an unstable system. But evidence of predictive behaviour is not readily apparent because anticipatory smooth movements cannot normally be generated at will. Over recent years we have carried out experiments designed to facilitate the generation of anticipatory movements and investigate their role in predictive pursuit (Barnes et al. 1987; Barnes and Asselman 1991; Wells and Barnes 1998). The model presented here was developed on the basis of the results from these experiments and attempts to demonstrate how predictive processes reduce phase errors during periodic tracking through the short-term storage of pre-motor drive information and its subsequent release to form anticipatory smooth movements.
KeywordsVisual Feedback Phase Error Smooth Pursuit Target Velocity Ocular Pursuit
Unable to display preview. Download preview PDF.
- Barnes GR. (1994) A model of predictive processes in oculomotor control based on experimental results in humans. In: Information processing underlying gaze control. Ed: Delgado-Garcia JM. Pergamon Press: Oxford, pp. 279–290.Google Scholar
- Barnes GR, Asselman PT (1991) The mechanism of prediction in human smooth pursuit eye movements.. J Physiol (Lond) 439: 439–461Google Scholar
- Barnes GR, Donelan AS (1997) Evidence for segregation of timing and velocity storage in ocular pursuit. J.Physiol (Lond) 505P:79–80PGoogle Scholar
- Barnes GR, Donnelly SF, Eason RD (1987) Predictive velocity estimation in the pursuit reflex response to pseudorandom and step displacement in man. J Physiol (Lond) 389:111–136Google Scholar
- Barnes GR, Rathbone K, Sira M. (1997). Effects of a structured background on anticipatory ocular pursuit. J.Physiol. (Lond) 505P:113PGoogle Scholar
- Kommerell G, Taümer R (1972) Investigations of the eye tracking system through stabilised retinal images. In: Bizzi E (ed) Bibl.ophthal. Karger. Basel, pp 288–297Google Scholar
- Wells SG, Barnes GR (1998) Fast, anticipatory smooth-pursuit eye movements appear to depend on a short-term store. Exp Brain Res. (In press).Google Scholar