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Dear Canice we have been looking at fixation stability both in terms of intrusive saccades duing fixation of a stationary fixation point (simple fixation instability)and in terms of slow drifts of the two eyes defined by the non-zero relative velocity between the rigth and the left eye (binocular fixation instability) We have been using velocity and amplitude criteria for detecting saccades that are within the range of the main sequence thereby eliminating most artifacts. We have been using also velocity criteria to find significant deviations of the relative velocity from zero. We have been applied this analysis to the data of 72 control and 68 dyslexic children. We found that there exits a long lasting development of both types of stability. The data of the two domains do not correlate. Dyslexic children have poorer stability in both domains. Because of the scatter in the data the estimate of the proportion of dyslexics involved is about 25%. Best regards BFischer -- Burkhart Fischer, Universitaet Freiburg, AG Hirnforschung Hansastr. 9, 79104 Freiburg, Germany, Tel ++49 761 203 9535, Fax 9540 [log in to unmask] www.brain.uni-freiburg.de/fischer/ -- 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]