Eye movements during real-life activities in humans

Most of the actions that make up our lives involve vision, if we are normally sighted. Because our eye movements are generally not accessible to conscious scrutiny, we tend to think of the eyes as passive receivers taking up and passing on the information required for the particular task. Is this really the case? It appears not: eye movements are proactive, anticipating actions rather than responding to stimuli. We have developed a light-weight, highly portable, video-based eye-tracker which allows us to study eye movements during real-life tasks. Whilst we study a very wide range of everyday activities, our current areas of interest are: (1) the roles of vision during everyday, automated tasks such as making cups of tea, (2) eye movements in the control of steering whilst driving a car, and (3) how we use vision to hit a cricket ball. To find out more about these projects click on the links below.

 Visual perception and the psychology of seeing

As we look around the world our overriding impression is that we see the world in a complete and smoothly changing way. However, the eyes do not work like this. The "saccade-and-fixate" strategy of the eyes means that during fixations, when the direction of gaze is stationary, the retina receives a static "snapshot" of the scene. During saccades (rapid movements of the eyes) our visual system is effectively blind. When the eye is stationary again for the next fixation, the retina receives a static snapshot of the new scene. The input to the visual system, therefore, is a series of (sometimes quite unrelated) static glimpses of the world. From where does our stable visual percept arise? Various explanations have been suggested in the past and until recently, many researchers felt that this problem had largely been resolved. However, in the light of recent change detection studies, we have had to overhaul our notions of how perceptual stability might be achieved by the visual brain. In our group we study two key issues:(1) the possibility of very short term point-by-point representation of what we are looking at and (2) the possibility of longer term, abstract representations constructed from information extracted from what we have looked at. We approach both of these issues with a strong emphasis upon naturalness in the experimental protocols because it is from the study of vision under near-naturalistic conditions that we can potentially learn the most about its operation. To find out more about this research project click on the link below.

 The structure of animal eyes

Eyes produce images in a wide variety of ways, some of which have been discovered only in the last few decades. Eyes are also adapted to the ecology and lifestyles of the animals that possess them, and some of the work described here discusses this. For example, in what ways are the optical structures of insect eyes adapted to meet the needs of flight, and how do the eyes of animals from the deep-sea environment achieve extreme sensitivity? Eye movements are important in all animals with good eye-sight, and several papers discuss the similarities and differences of oculomotor behaviour across the animal kingdom. In insects, eye and body movements are often the same and early studies of pursuit in hoverflies (with Tom Collett) demonstrated remarkable similarities between their body movements and our eye movements.

At present we are studying the eyes of two species of mosquito, trying to unravel the details of the neural structures involved in transferring information from the retina.

This page is maintained by Ben Tatler (b.w.tatler@sussex.ac.uk)

Last updated 26 July 2004