Three studies, using a videotaped trial context, examined jurors' understanding of the standardized pattern instruction about eyewitness reliability and the effects of revisions of these instructions using simplified language. Results indicate that the widely used TELFAIRE instructions are not especially effective in educating jurors about the vagaries of eyewitness memory. Compared to jurors who heard the standard instructions, those who heard the revised instructions were more knowledgeable of the factors to consider when evaluating eyewitness testimony and were less likely to convict the defendant. A sample of U.S. superior court judges thought the simplified instruction was more effective than the existing version in conveying intended legal concepts to the jury, but also rated it as more strongly biased toward the defense. 6 tables and 25 references. (Author abstract modified)