Optological Laboratory
Research Team
- Dr Andrew J Anderson
- Dr Ruth Hogg
- Ms Deborah Hackett
National & International Collaborators
- Dr Chris A Johnson - Discoveries in Sight, Portland, USA
- Dr RHS Carpenter - The Physiological Laboratory, University of Cambridge, UK
Laboratory Information
Our laboratory primarily uses psychophysical methods to measure how people respond to customised visual targets, presented on a calibrated computer monitor. A number of these customised targets are designed to investigate how the human visual system processes the targets used in clinical tests of vision, such as visual field tests (e.g. Frequency Doubling Technology perimetry), thereby furthering our understanding of how the eye sees as well as allowing more effective clinical tests to be developed.
The laboratory also has collaborative links with the Oculomotor Laboratory, The University of Cambridge, UK, headed by Dr RHS Carpenter. By marrying our computer display equipment with eye-movement tracking apparatus, we can investigate how various aspects of visual targets (e.g. contrast, colour, probability of appearing) influence where we decide to look with our eyes. This information also gives us insight into the more general processes of how the brain makes decisions, based on the evidence presented to it.
Some of our current projects are outlined below:
Mechanisms Underlying Inter-eye Sensitivity Losses in Frequency Doubling Perimetry
The Matrix perimeter is a newly developed clinical test that uses flickering grating targets to measure the integrity of a patient's visual field. Recent work (Anderson AJ et al., 2005. Invest Ophthalmol Vis Sci, 46:1540-1548) has shown that when a patient's second eye is tested, sensitivity to the grating targets is reduced when compared to the first eye, and that this reduction is not uniform across the visual field; it tends to be more marked for the part of the visual field furthest away from the patient's nose!
We are studying, in conjunction with Dr Allision McKendrick, the causes of this sensitivity loss, which is likely due to a difference in light adaptation between the two eyes (Anderson AJ, Johnson CA, 2002. Optom Vis Sci, 79, 88-92). By understanding how such sensitivity losses arise, we can establish whether they significantly affect visual field tests and, if so, what strategies might be employed to minimise these effects.
Using Eye Movements to Study how Past Experiences Shape Expectations
It is well established that when we expect a visual target to appear in a certain location, it takes a reduced time to make an eye movement to the target when it finally does appear. What is not clear is how the brain uses the pattern of where the target has previously appeared to determine an expectation for where it will appear in the future.
In collaboration with Dr RHS Carpenter, we are investigating how long it takes the brain's "expectation" signal to change when we abruptly alter the probability that a target will appear at a particular location. By understanding how expectation influences comparatively simple and common decisions, such as deciding where to look next with our eyes, we also hope to learn something about the more general process of how the brain uses experiences to shape an expectation of what will happen in the future.
Selected Recent Publications
- Anderson AJ, Johnson CA, Fingeret M, Keltner JL, Spry PG, Wall M, Werner JS (2005). Characteristics of the normative database for the Humphrey matrix perimeter. Invest Ophthalmol Vis Sci; 46(4): 1540-1548.
- Anderson AJ (2004). Eye movements: viewing the window of opportunity. Curr Biol; 14(22): R951-R952.
- McKendrick, A.M., Anderson, A. J., Johnson, C. A. & Fortune, B. (2003). Appearance of the frequency doubling stimulus at threshold, in normals and glaucoma patients. Investigative Ophthalmology and Visual Science, 44, 1111-1116.
- Anderson, A. J. & Johnson, C. A. (2003). Anatomy of a super-group: does a criterion of normal perimetric performance generate a super-normal population? Investigative Ophthalmology and Visual Science, 44, 5043-5048.