Since its inception, the International Research Group on Colour Vision Deficiencies (IRGCVD) has followed the policy that the Symposium Pro­ ceedings should be as close as possible to a complete record of the scientific content of the meeting. This policy has the advantage of providing an accurate picture of the current state of the art in research on color vision deficiencies, but it also has the disadvantage that papers typically span a wide range of quality. In this volume, however, we have instituted a system of peer review in an effort to enhance scientific quality as much as possible while continuing our past policy of publishing all submitted manuscripts. In addition to being edited for English composition and grammar, each of the papers included here has been carefully reviewed by an IRGCVD member selected for his or her expertise in the specific topic of the paper. Reviewers were instructed to include in their comments suggestions for improvement rather than recom­ or rejection. In our opinion, this review process mendations for publication has resulted in substantial improvement of many of the articles and has enhanced the value of the publication. We are pleased to acknowledge the efforts of our reviewers and offer them our sincere thanks for their important contributions to Colour Vision Deficiencies X. The Editors B. Drum, J. D. Moreland & A. Serra (eds. ), Colour Vision Deficiencies X, p. xiii.

The eleventh Symposium of the International Research Group on Colour Vision Deficiencies (IRGCVD) was held 20-23 June 1991 in Sydney, Aus­ tralia, ably hosted by local organizer Stephen Dain. A total of 35 talks and 10 posters were presented. Papers based on 37 of these presentations are included here, in Colour Vision Deficiencies XI. The scientific program featured sessions on three special topics, with each topic highlighted by an invited speaker. The opening session on the Genetics of congenital colour vision deficiencies began with a superb invited lecture by Charles Weitz about his pioneering work on the molecular genetics of tritanopia. The session on the second special topic, Spatial aspects of colour vision, began with the launching of a new IRGCVD tradition, as 1991 Verriest Memorial Award recipient Harry Sperling presented the first Ver­ riest Memorial Lecture on his recent studies of spatial discrimination of heterochromatic stimuli. Dr. Sperling reported new evidence that certain asymmetries in red-green opponent colour vision can be explained by the spatial organization of colour-opponent retinal neurons. In the third special session, on Occupational aspects of colour vision, Barry Cole took the audi­ ence on a fascinating tour of the historical development of colour vision standards in his invited lecture entitled 'Does defective colour vision really matter?'. In addition to the three special topics, many interesting presentations were given in topical sessions on Variations in normal colour vision, Acquired colour vision deficiencies and Colour vision tests and testing methods.

From the 98 presentations of the XIIth Symposium on Colour Vision Deficiencies, 61 were selected after peer review and revision by the authors. In addition to these contributions this volume contains a cumulative index to all authors in the IRGCVD proceedings since the first one in 1968, including the present volume. The contents include contributions on basic questions of anatomical and electrophysiological organization of the neural pathways underlying colour vision; and on ways in which disturbances of these pathways can produce acquired colour vision deficiencies. Further contributions deal with genetics and congenital red-green colour deficiencies and colour vision testing. The resulting publication should contain much of interest to basic vision scientists as well as to specialists in colour vision deficiencies.

Proceedings of the Ninth symposium of the International Research Group on Colour Vision Deficiencies, held at St. John's College, Annapolis, MD, July 1-3, 1987.

From the 98 presentations of the XIIth Symposium on Colour Vision Deficiencies, 61 were selected after peer review and revision by the authors. In addition to these contributions this volume contains a cumulative index to all authors in the IRGCVD proceedings since the first one in 1968, including the present volume. The contents include contributions on basic questions of anatomical and electrophysiological organisation of the neural pathways underlying colour vision; and on ways in which disturbances of these pathways can produce acquired colour vision deficiencies. Further contributions deal with genetics and congenital red--green colour deficiencies and colour vision testing. The resulting publication contains much of interest to basic vision scientists as well as to specialists in colour vision deficiencies.

The eleventh Symposium of the International Research Group on Colour Vision Deficiencies (IRGCVD) was held 20-23 June 1991 in Sydney, Aus­ tralia, ably hosted by local organizer Stephen Dain. A total of 35 talks and 10 posters were presented. Papers based on 37 of these presentations are included here, in Colour Vision Deficiencies XI. The scientific program featured sessions on three special topics, with each topic highlighted by an invited speaker. The opening session on the Genetics of congenital colour vision deficiencies began with a superb invited lecture by Charles Weitz about his pioneering work on the molecular genetics of tritanopia. The session on the second special topic, Spatial aspects of colour vision, began with the launching of a new IRGCVD tradition, as 1991 Verriest Memorial Award recipient Harry Sperling presented the first Ver­ riest Memorial Lecture on his recent studies of spatial discrimination of heterochromatic stimuli. Dr. Sperling reported new evidence that certain asymmetries in red-green opponent colour vision can be explained by the spatial organization of colour-opponent retinal neurons. In the third special session, on Occupational aspects of colour vision, Barry Cole took the audi­ ence on a fascinating tour of the historical development of colour vision standards in his invited lecture entitled 'Does defective colour vision really matter?'. In addition to the three special topics, many interesting presentations were given in topical sessions on Variations in normal colour vision, Acquired colour vision deficiencies and Colour vision tests and testing methods.

Since its inception, the International Research Group on Colour Vision Deficiencies (IRGCVD) has followed the policy that the Symposium Pro­ ceedings should be as close as possible to a complete record of the scientific content of the meeting. This policy has the advantage of providing an accurate picture of the current state of the art in research on color vision deficiencies, but it also has the disadvantage that papers typically span a wide range of quality. In this volume, however, we have instituted a system of peer review in an effort to enhance scientific quality as much as possible while continuing our past policy of publishing all submitted manuscripts. In addition to being edited for English composition and grammar, each of the papers included here has been carefully reviewed by an IRGCVD member selected for his or her expertise in the specific topic of the paper. Reviewers were instructed to include in their comments suggestions for improvement rather than recom­ or rejection. In our opinion, this review process mendations for publication has resulted in substantial improvement of many of the articles and has enhanced the value of the publication. We are pleased to acknowledge the efforts of our reviewers and offer them our sincere thanks for their important contributions to Colour Vision Deficiencies X. The Editors B. Drum, J. D. Moreland & A. Serra (eds. ), Colour Vision Deficiencies X, p. xiii.

Proceedings of the Ninth symposium of the International Research Group on Colour Vision Deficiencies, held at St. John's College, Annapolis, MD, July 1-3, 1987.

From the 98 presentations of the XIIth Symposium on Colour Vision Deficiencies, 61 were selected after peer review and revision by the authors. In addition to these contributions this volume contains a cumulative index to all authors in the IRGCVD proceedings since the first one in 1968, including the present volume. The contents include contributions on basic questions of anatomical and electrophysiological organisation of the neural pathways underlying colour vision; and on ways in which disturbances of these pathways can produce acquired colour vision deficiencies. Further contributions deal with genetics and congenital red--green colour deficiencies and colour vision testing. The resulting publication contains much of interest to basic vision scientists as well as to specialists in colour vision deficiencies.

The eleventh Symposium of the International Research Group on Colour Vision Deficiencies (IRGCVD) was held 20-23 June 1991 in Sydney, Aus­ tralia, ably hosted by local organizer Stephen Dain. A total of 35 talks and 10 posters were presented. Papers based on 37 of these presentations are included here, in Colour Vision Deficiencies XI. The scientific program featured sessions on three special topics, with each topic highlighted by an invited speaker. The opening session on the Genetics of congenital colour vision deficiencies began with a superb invited lecture by Charles Weitz about his pioneering work on the molecular genetics of tritanopia. The session on the second special topic, Spatial aspects of colour vision, began with the launching of a new IRGCVD tradition, as 1991 Verriest Memorial Award recipient Harry Sperling presented the first Ver­ riest Memorial Lecture on his recent studies of spatial discrimination of heterochromatic stimuli. Dr. Sperling reported new evidence that certain asymmetries in red-green opponent colour vision can be explained by the spatial organization of colour-opponent retinal neurons. In the third special session, on Occupational aspects of colour vision, Barry Cole took the audi­ ence on a fascinating tour of the historical development of colour vision standards in his invited lecture entitled ''Does defective colour vision really matter?''. In addition to the three special topics, many interesting presentations were given in topical sessions on Variations in normal colour vision, Acquired colour vision deficiencies and Colour vision tests and testing methods.

Since its inception, the International Research Group on Colour Vision Deficiencies (IRGCVD) has followed the policy that the Symposium Pro­ ceedings should be as close as possible to a complete record of the scientific content of the meeting. This policy has the advantage of providing an accurate picture of the current state of the art in research on color vision deficiencies, but it also has the disadvantage that papers typically span a wide range of quality. In this volume, however, we have instituted a system of peer review in an effort to enhance scientific quality as much as possible while continuing our past policy of publishing all submitted manuscripts. In addition to being edited for English composition and grammar, each of the papers included here has been carefully reviewed by an IRGCVD member selected for his or her expertise in the specific topic of the paper. Reviewers were instructed to include in their comments suggestions for improvement rather than recom­ or rejection. In our opinion, this review process mendations for publication has resulted in substantial improvement of many of the articles and has enhanced the value of the publication. We are pleased to acknowledge the efforts of our reviewers and offer them our sincere thanks for their important contributions to Colour Vision Deficiencies X. The Editors B. Drum, J. D. Moreland & A. Serra (eds. ), Colour Vision Deficiencies X, p. xiii.

The eleventh Symposium of the International Research Group on Colour Vision Deficiencies (IRGCVD) was held 20-23 June 1991 in Sydney, Aus­ tralia, ably hosted by local organizer Stephen Dain. A total of 35 talks and 10 posters were presented. Papers based on 37 of these presentations are included here, in Colour Vision Deficiencies XI. The scientific program featured sessions on three special topics, with each topic highlighted by an invited speaker. The opening session on the Genetics of congenital colour vision deficiencies began with a superb invited lecture by Charles Weitz about his pioneering work on the molecular genetics of tritanopia. The session on the second special topic, Spatial aspects of colour vision, began with the launching of a new IRGCVD tradition, as 1991 Verriest Memorial Award recipient Harry Sperling presented the first Ver­ riest Memorial Lecture on his recent studies of spatial discrimination of heterochromatic stimuli. Dr. Sperling reported new evidence that certain asymmetries in red-green opponent colour vision can be explained by the spatial organization of colour-opponent retinal neurons. In the third special session, on Occupational aspects of colour vision, Barry Cole took the audi­ ence on a fascinating tour of the historical development of colour vision standards in his invited lecture entitled 'Does defective colour vision really matter?'. In addition to the three special topics, many interesting presentations were given in topical sessions on Variations in normal colour vision, Acquired colour vision deficiencies and Colour vision tests and testing methods.

From the 98 presentations of the XIIth Symposium on Colour Vision Deficiencies, 61 were selected after peer review and revision by the authors. In addition to these contributions this volume contains a cumulative index to all authors in the IRGCVD proceedings since the first one in 1968, including the present volume. The contents include contributions on basic questions of anatomical and electrophysiological organization of the neural pathways underlying colour vision; and on ways in which disturbances of these pathways can produce acquired colour vision deficiencies. Further contributions deal with genetics and congenital red-green colour deficiencies and colour vision testing. The resulting publication should contain much of interest to basic vision scientists as well as to specialists in colour vision deficiencies.

Proceedings of the Ninth symposium of the International Research Group on Colour Vision Deficiencies, held at St. John's College, Annapolis, MD, July 1-3, 1987.

From the 98 presentations of the XIIth Symposium on Colour Vision Deficiencies, 61 were selected after peer review and revision by the authors. In addition to these contributions this volume contains a cumulative index to all authors in the IRGCVD proceedings since the first one in 1968, including the present volume. The contents include contributions on basic questions of anatomical and electrophysiological organisation of the neural pathways underlying colour vision; and on ways in which disturbances of these pathways can produce acquired colour vision deficiencies. Further contributions deal with genetics and congenital red--green colour deficiencies and colour vision testing. The resulting publication contains much of interest to basic vision scientists as well as to specialists in colour vision deficiencies.

The eleventh Symposium of the International Research Group on Colour Vision Deficiencies (IRGCVD) was held 20-23 June 1991 in Sydney, Aus­ tralia, ably hosted by local organizer Stephen Dain. A total of 35 talks and 10 posters were presented. Papers based on 37 of these presentations are included here, in Colour Vision Deficiencies XI. The scientific program featured sessions on three special topics, with each topic highlighted by an invited speaker. The opening session on the Genetics of congenital colour vision deficiencies began with a superb invited lecture by Charles Weitz about his pioneering work on the molecular genetics of tritanopia. The session on the second special topic, Spatial aspects of colour vision, began with the launching of a new IRGCVD tradition, as 1991 Verriest Memorial Award recipient Harry Sperling presented the first Ver­ riest Memorial Lecture on his recent studies of spatial discrimination of heterochromatic stimuli. Dr. Sperling reported new evidence that certain asymmetries in red-green opponent colour vision can be explained by the spatial organization of colour-opponent retinal neurons. In the third special session, on Occupational aspects of colour vision, Barry Cole took the audi­ ence on a fascinating tour of the historical development of colour vision standards in his invited lecture entitled 'Does defective colour vision really matter?'. In addition to the three special topics, many interesting presentations were given in topical sessions on Variations in normal colour vision, Acquired colour vision deficiencies and Colour vision tests and testing methods.

Since its inception, the International Research Group on Colour Vision Deficiencies (IRGCVD) has followed the policy that the Symposium Pro­ ceedings should be as close as possible to a complete record of the scientific content of the meeting. This policy has the advantage of providing an accurate picture of the current state of the art in research on color vision deficiencies, but it also has the disadvantage that papers typically span a wide range of quality. In this volume, however, we have instituted a system of peer review in an effort to enhance scientific quality as much as possible while continuing our past policy of publishing all submitted manuscripts. In addition to being edited for English composition and grammar, each of the papers included here has been carefully reviewed by an IRGCVD member selected for his or her expertise in the specific topic of the paper. Reviewers were instructed to include in their comments suggestions for improvement rather than recom­ or rejection. In our opinion, this review process mendations for publication has resulted in substantial improvement of many of the articles and has enhanced the value of the publication. We are pleased to acknowledge the efforts of our reviewers and offer them our sincere thanks for their important contributions to Colour Vision Deficiencies X. The Editors B. Drum, J. D. Moreland & A. Serra (eds. ), Colour Vision Deficiencies X, p. xiii.

Proceedings of the Ninth symposium of the International Research Group on Colour Vision Deficiencies, held at St. John's College, Annapolis, MD, July 1-3, 1987.

From the 98 presentations of the XIIth Symposium on Colour Vision Deficiencies, 61 were selected after peer review and revision by the authors. In addition to these contributions this volume contains a cumulative index to all authors in the IRGCVD proceedings since the first one in 1968, including the present volume. The contents include contributions on basic questions of anatomical and electrophysiological organisation of the neural pathways underlying colour vision; and on ways in which disturbances of these pathways can produce acquired colour vision deficiencies. Further contributions deal with genetics and congenital red--green colour deficiencies and colour vision testing. The resulting publication contains much of interest to basic vision scientists as well as to specialists in colour vision deficiencies.

The eleventh Symposium of the International Research Group on Colour Vision Deficiencies (IRGCVD) was held 20-23 June 1991 in Sydney, Aus­ tralia, ably hosted by local organizer Stephen Dain. A total of 35 talks and 10 posters were presented. Papers based on 37 of these presentations are included here, in Colour Vision Deficiencies XI. The scientific program featured sessions on three special topics, with each topic highlighted by an invited speaker. The opening session on the Genetics of congenital colour vision deficiencies began with a superb invited lecture by Charles Weitz about his pioneering work on the molecular genetics of tritanopia. The session on the second special topic, Spatial aspects of colour vision, began with the launching of a new IRGCVD tradition, as 1991 Verriest Memorial Award recipient Harry Sperling presented the first Ver­ riest Memorial Lecture on his recent studies of spatial discrimination of heterochromatic stimuli. Dr. Sperling reported new evidence that certain asymmetries in red-green opponent colour vision can be explained by the spatial organization of colour-opponent retinal neurons. In the third special session, on Occupational aspects of colour vision, Barry Cole took the audi­ ence on a fascinating tour of the historical development of colour vision standards in his invited lecture entitled ''Does defective colour vision really matter?''. In addition to the three special topics, many interesting presentations were given in topical sessions on Variations in normal colour vision, Acquired colour vision deficiencies and Colour vision tests and testing methods.