視覺科學學會第四屆年會

參與會議報告

葉素玲

台灣大學心理學系暨研究所

視覺科學學會（Vision Sciences Society, VSS）在四年前脫離視覺與光學研究學會（Association for Research in Vision and Ophthalmology, ARVO）獨立成立之後，每年固定在美國佛羅里達州的美麗濱海城市Sarasota舉辦。這兩個學會的分道揚鑣其實早已是預料中之事。當筆者還在攻讀博士學位時，ARVO獨大，每年所有視覺研究者時值四、五月，整個實驗室便為了ARVO忙翻天。持續成長至以萬人計的學術社群，眼科醫師便佔了大宗，造成基礎視覺研究者始終覺得在議題的排定與選擇上受到忽視。原先ARVO固定每年在Sarasota舉行，但後來由於人口膨脹到Sarasota這個小城已經無法容納的地步，因此整個會議移到擁有大型會議中心的Lauderdale（仍在佛羅里達州）舉行，也種下了基礎研究者意欲脫離的肇因。由哈佛大學心理系的Ken Nakayama發起，持續的意見調查與準備之後，終於在2000年宣告成立VSS，並將會議中心轉回Sarasota舉行。

2000年當VSS終於成立，並在Sarasota辦第一屆年會時，視覺研究者曾為了是否選邊站，以及選哪邊的問題傷透腦筋，於是出現了乾脆兩邊都參加、觀望意味濃厚的局面。然而，第二屆之後，態勢明朗，即便ARVO的主辦單位試圖以各種動作挽回局面，只見大勢已去。大多研究者若無法兩邊兼顧，便選了VSS，使得VSS在三、四年內人數激增。今年的會議於四月三十日至五月五日舉行，六天的會議中共安排了約200場口頭報告以及900篇的壁報發表。而自第一屆起VSS也爭取將論文摘要，皆刊登於處理快捷且快速成長的電子期刊 ”Journal of Vision”上。前幾年由於顧及有些人兩邊都要參加，VSS的開會日期還都避免與ARVO重疊，且定在剛好ARVO之前或之後幾天。今年在會員大會時，曾就明年舉辦的日期引起熱烈討論，而由討論的情勢看起來，VSS已經立穩根基，也有不打算繼續考慮與配合ARVO舉辦日期的聲音出現。

對於像我一般，所從事的研究屬於知覺與注意力的範圍（而非更低階的視覺生理或更高階的認知歷程），且採用各式研究方法的人，這個會議上千篇的論文感覺上是篇篇相關，絕不願有任何遺漏。大會的安排以主題為主，而不區分方法，因此電生理記錄、心理物理、電腦模擬、大腦造影、神經心理學等等，只要探討的主題相同，都可能放在同一個專題研討會中。然而對於探討視網膜或初級視覺皮質等機制的研究者而言，明顯地會覺得他們關心的議題所佔的比例不若ARVO，甚至不以網膜或視皮質作為主題，因此頗多抱怨，寧可回去參加ARVO。這些抱怨，與VSS成立前，研究者對ARVO的抱怨頗相似。歷史總是重蹈覆轍，分分合合，始終處在一種平衡的動力學當中。

自1997年去過Lauderdale參加ARVO之後，我就再也不曾與會。研究生時代每年去Sarasoto浸潤於科學熱誠中的甜美回憶，在Lauderdale過大的會議中心與過多的人群所造成疏離的感覺，使得不再嚮往每年一度的盛事，此其重要原因之一。另一原因則是ARVO 的時間是定在美國各大學已結束課程的五月，以便在大學任教的研究者可以輕鬆的與會。然而回台任教後，辛苦的奔波參與會議之後，還需補課與銜接最繁忙的期末，頗令人吃不消。自此之後，便轉往每年在暑假期間舉行的歐洲視知覺會議。

今年我會選擇再回Sarasota，主要原因是參加今年VSS為Russell L. DeValois辦的追悼紀念會。碰到許多過去的老同學，經提醒才驚覺上次在Sarasota出現，竟已是十多年前剛拿到博士學位期間，而這些同學竟也已紛紛成為資深研究者。我在柏克萊唸書時，在Russ DeValois與其夫人Karen DeValois的聯合指導下完成博士學位。Russ早年因為以單細胞的電生理技術，在彌猴的側膝核（Lateral Geniculate Nucleus, LGN）記錄到對色彩對比反應的細胞而著名。他在六零年代便被柏克萊加州大學由印第安那大學挖角，一直與其夫人在柏克萊心理系、視光學院、與整合生物所任教。去年九月，他們夫妻兩人至科羅拉多州參加高中同學會，回程因座車爆胎，導致Russ在醫院中昏迷不醒，十天後辭世。Karen則受重傷，出院後接回家中休養。Russ昏迷期間，大家聞訊都擔心異常。他曾因換膝蓋導致血拴，在加護病房急救，後來奇蹟似地康復，因此我們這些學生們總祈禱能像從前一般有奇蹟出現。他的辭世是視覺研究社群的一大損失。他在76歲過世，然而對所有認識他、瞭解他的人而言，他是永遠不老的。UC Berkeley news刊登了一篇他的消息，相當程度地反映了他的同事、朋友、與學生們對他的看法（附錄於後）。

今年的大會，由於與會人數及論文發表數都相當龐大，除了安排每天上下午兩個場次的演講、每個場次有2至3個主題同時舉行之外，還有每天兩場的壁報展。追悼會特地安排在五月二日晚間舉行，將原先兩個演講廳拉開中間的隔牆，合併為一個，以容納所有的人。追悼會由Russ生前好友Tony Adams與Eugene Switkes主持，前者是柏克萊視光學院的前院長，後者是UC Santa Cruz化學系的教授，長期與Russ合作研究色彩細胞的運作機制。繼他們簡短說明Russ的生平事蹟之後，由Gerald Jacobs 與Robert Shapley 分別就色彩視覺與空間視覺這兩大領域說明Russ的貢獻。

Jacobs是Russ的第一位學生，在經典的LGN論文中他是作者之一，現在是Santa Barbara著名的色彩專家。由於他的研究取向為生態與比較心理學(ecological and comparative psychology)，近年並與Neitz夫婦合作研究色彩視覺的基因機轉，因此會出現在VSS完全是為了Russ的追悼會而來。Shapley在紐約大學任教，是空間視覺研究領域的大將，與Russ有著類似的科學家氣質與堅持。由他們兩位專家分別就色彩與空間視覺領域來介紹Russ的學術成就，Russ地下有知，應該也會感到欣慰的。

過去當ARVO還在Sarasota舉行的年代，每次De Valois實驗室的學生們都會於一家海鮮餐廳聚餐，前後屆老老小小的學生齊聚一堂。今年Karen也帶著她女兒和孫女前來參加追悼會，因此大家還是如往昔一般聚餐。在那個餐廳來來往往的賓客中，竟有許多熟識者，他們一一前來向Karen致意問候，令人不禁感傷起來。想起許多往事：想起Tony還在當視光學院長時，Russ常幫忙作幕僚，寫願景書（Russ的高瞻遠矚與不善行政是眾所周知的）; 想起Russ針對動物保護組織人士各種攻擊行動的豁達（Karen為此放棄做動物實驗，理由是「萬一發生甚麼事，總要有一人留下來照顧孩子」）; 想起Tony、Eugene、與Russ每週兩次打網球，Russ總是站著不動，而等到他兩個膝蓋都要換成人工的，我們才知道每天埋首於實驗室的他，其實膝蓋一直是極端疼痛的（他車禍的消息甫發生就在Berkeley傳開，就是因為這些球友們苦等他不到，而他從未缺席）; 想起他總在冬天開著一輛邊吹暖氣邊迎著四周冷風的紅色敞篷英式跑車，此車三不五時必須進廠修理，卻總在進廠時找不出毛病 ; 想起不知多少次深深感佩於他對科學的熱忱，驚訝於一個在科學領域如此犀利嚴謹的人，竟可以同時在生活與性格方面如此多采多姿而充滿魅力。

1997年夏天，Russ與Karen曾應邀來台講學（承蒙國科會資助），有一天我們一行人至野柳與九份旅遊。往往當我們坐定，Russ與他女兒不知已經走到哪裡了。野柳的石岸與九份的階梯，都無法阻檔他的冒險精神。「他真的已經70歲了嗎？」是我們立即浮起的問題。這次追悼會播放他生前的照片，其中有一張照片便是他在台灣講學時的情況，雖然Eugene事先告訴我有安排這麼一張照片，看了還是感觸萬千。那一年在他們夫婦來台灣之前，著名的色彩視覺研究搭檔、芝加哥大學教授Joe Pokorny & Vivianne Smith也來台講學。六年後，Pokorny & Smith夫婦又應台灣色彩學會之邀，於2003年冬第二次訪台。我們一見面聊起來，竟還是Russ辭世對大家的震撼。Pokorny & Smith夫婦在來台之前參加了原先要表揚Russ的成就，後來竟變成追悼會的美國光學會舉辦的Fall Vision Meeting。對於人生的無常，除了不勝欷噓，還能何如？

在VSS碰到許多昔日柏克萊視光學院與心理系的師長，多年不見的Stanley Klein教授說：「Karen 恢復得不錯，在Berkeley所有朋友都盡量讓她忙碌（她剛卸下心理系系主任一職）。」我曾經在那個溫暖親切的環境中探求知識，每週三在Russ和Karen位於Berkeley山上的家，人手一杯紅酒，與這群老師同學們討論視覺的種種。幾位教授在視覺領域都是翹楚者，竟能和諧地維持著親密的同僚與友誼關係，無論在何時何地，這樣的情況都可算是異數。我總認為，Russ的無私與宏偉的氣度、Karen的圓潤處事風格，都扮演了重要的關鍵角色。我感念那段在Berkeley與他們朝夕相處的日子。在我心中，Russ是永遠的導師。

僅以此文獻給我最敬愛的Russ De Valois -- 哲人雖已遠，典型在夙昔。

2004. 9. 4.於台北

De Valois memorial (May 2, 2004)

De Valois 的實驗室聚餐（at the Moore’s stone crab restaurant）

左排第三位：Karen De Valois，第四位：Eugene Switkes

右排第一位：Tony Adams

與 Karen DeValois & Eugene Switkes 合影

附錄：

UC Berkeley News – Press Release

（http://www.berkeley.edu/news/media/releases/2003/09/25_devalois.shtml）

Pioneering vision researcher Russell De Valois has died at 76

By Robert Sanders, Media Relations | 25 September 2003

Russell De Valois, a professor of psychology and vision science who died Sept. 20. Print-quality photo available for download

BERKELEY – Russell L. De Valois, a professor of psychology and vision science at the University of California, Berkeley, whose experiments resolved a century-old debate about color vision and generated new ideas about spatial vision, died Saturday, Sept. 20, as the result of an automobile accident.

De Valois, 76, was a passenger in a car that crashed in Rock Springs, Wyo., on Sept. 10. He lapsed into a coma and died 10 days later at the University of Utah Medical Center in Salt Lake City. His wife, Karen K. De Valois, also a UC Berkeley professor of psychology and vision science, was injured in the accident as well, but has been released from the hospital.

"He was a pioneer in trying to explain how psychophysical phenomena, such as how we discriminate colors and describe subjective differences in color, are related to neuronal activity," said longtime colleague and collaborator Eugene Switkes, professor of chemistry at UC Santa Cruz and an affiliate of UC Berkeley's School of Optometry.

In the past few years, De Valois had collaborated with his wife - "they were close, but complementary, intellectual colleagues," Switkes said - on a model which further describes the details of color vision.

At the time of his death, Russell De Valois was working on a new theory of how brain cells encode information about motion.

"Typical of Russ, it's an outrageous theory that probably has more truth than outrage to it," said Switkes.

De Valois, who also held appointments in the campus's School of Optometry and Helen Wills Neuroscience Institute, sometimes used humans and monkeys in behavioral visual tests, called psychophysical studies. More often, his experiments involved inserting electrodes into the brains of macaques and cats to determine how individual brain cells respond to color, form, images or movement. He pioneered recording from individual neurons in subcortical brain structures, developing methods that are now widely used in laboratories around the world.

"He tried to correlate electrical events in the brain with actual behavior to discover how we see color and perceive spatial information," Switkes said. "He was always interested in what the cells can tell us - 'listening to what the cells had to say.'"

These animal studies, which De Valois continued until just a few years ago, could contribute to the development of visual prostheses for the blind, Switkes said.

"People, including at least one of Russ's former students, are working on prosthetic devices that stimulate cells in the brain's visual cortex to create visual sensation and, hopefully, vision," he said. "The first stage in making this work is understanding what these cells do, and that's what Russ's contribution was."

According to his colleagues, De Valois often remarked, "Before you can fix an instrument, you have to understand how it is supposed to work."

De Valois' UC Berkeley colleagues spoke with admiration and affection of his great intellect and his gift for teaching.

"He was truly a great man, with one of the most clear and concise minds I've ever seen," said Ervin Hafter, a colleague in the psychology department. "He was fabulous as a mentor to graduate students, and had become a 'grand old man' of the department."

"Russ was a great colleague," added Dennis M. Levi, dean of the School of Optometry. "He was a brilliant and accomplished scientist, an incredibly dedicated teacher, and a wonderful, warm human being. He will be sorely missed by all whose lives were touched by him."

De Valois was born in Ames, Iowa, on Dec. 15, 1926, and followed his parents to India, where they served as missionaries for the Dutch Reformed Church. He attended school in Kodaikanal, India, returning to the United States in 1943 to enter Oberlin College. After obtaining his A.B. in zoology and physiology in 1947 and his M.A. in psychology in 1948, he entered the University of Michigan, earning his Ph.D. in physiological psychology in 1952.

Following research and teaching stints at the University of Michigan and a post-doctoral appointment in Germany, he joined the faculty at Indiana University in Bloomington, where he first made a name for himself by describing the brain mechanisms behind color vision.

Based on single-cell recordings from a region of the thalamus called the lateral geniculate nucleus (LGN), he showed how monkeys, and by extension humans, perceive many different colors despite the fact that the eyes' color-sensing cones contain only three types of broadly selective photoreceptors. He found that cells in the brain may be activated by light of one color and cease firing when presented with a different color. The brain cells do a sort of "algebra," he said, to calculate the wavelength region of light and allow us to perceive the full range of colors. His discovery of neurons with "opponent color organization" helped to explain our perception of the primary colors and color combinations, and resolved arguments dating from the 19th century about color perception.

In careful experiments, he subsequently showed that what he discovered in monkeys applied also to the early stages of color processing in humans.

"The understanding of the nature of basic information about color at the levels of the cone receptors and the LGN, and the knowledge about how the simple cone information is processed by the neurons of the color vision pathway, are two critical contributions that Dr. Russell De Valois has provided vision science, giving it its first true insight into the mechanism of color vision," wrote Cynthia M. Langley of Indiana University in 1989 upon De Valois' receipt of the prestigious 1988 Edgar D. Tillyer Medal, one of the highest honors awarded by the Optical Society of America.

De Valois and his students also shed light on human color-blindness by showing that certain species of New World monkeys showed impaired red-green vision similar to a type of red-green impairment found in a small percentage of human males.

In 1968, De Valois joined the faculty at UC Berkeley, where he continued his color vision research and also began looking at perception of spatial information and how it is analyzed and encoded in the brain. Often in collaboration with his wife, he concentrated on the early stages of spatial vision, in particular how our perception varies depending on the graininess or resolution of what we see. They found, in analogy with color vision, that brain cells are tuned to specific bands of spatial frequency and orientation.

This so-called spatial frequency analysis is exploited in making the connection between how our brain perceives an image and how JPEG pictures are often coded and transmitted across the Internet - first appearing as a coarse-grained image, and later filled in with fine detail. Much of this work was conducted on cats, which, though essentially colorblind, provide a good model for human spatial vision.

The couple also looked at how color and luminance variations contribute to spatial perception. They published an influential book, "Spatial Vision," in 1988 that summarized two decades of work by vision researchers.

"The impact of this work extends beyond the community of physiologists and psychologists studying vision," said Anthony J. Adams, professor and former dean of UC Berkeley's School of Optometry. "The strategies used by the human visual system to encode color, pattern and movement, as revealed by De Valois and colleagues, are being employed by engineers currently developing economic image encoding schemes for the United States HDTV (high definition television) initiative."

At the time of his death, De Valois and his wife were working on a companion book, to be called "Color Vision," and a multistage model of color perception.

Away from the lab, De Valois enjoyed life to the fullest, Hafter said. "Whether hiking in the mountains or skiing or traveling to favorite places or eating favorite foods or playing tennis with friends or driving his beloved red sports car," he said, "every act of living was an adventure."

De Valois was a member of the National Academy of Sciences and a recipient of various awards, including the Tillyer Medal of the Optical Society of America, the Warren Medal of the Society of Experimental Psychologists and the Distinguished Scientific Contribution Award of the American Psychological Association. He was a Fulbright Fellow, a William James Fellow of the American Psychological Society and a fellow of the American Association for the Advancement of Science.

At the Optical Society of America meeting next week in Arizona, two special symposia will be dedicated to DeValois' career in honor of his work in the psychophysics and physiology of vision.

De Valois is survived by his wife of 34 years, Karen (Kennedy) De Valois; two children with Karen, Chad of Oakland and Kamala De Valois of Berkeley; three children by a previous marriage, Geoffrey of Los Angeles, Gregory of San Jose and Gordon of Oakland; a son-in-law, Michael Ellis, of Berkeley; sisters Margaret Van Anrooy of Woodland Park, Colo., and Francine Schramm of Brookfield, Wisc.; a brother, John James De Valois Jr., of Redwood City, Calif.,; two grandchildren; and numerous nieces and nephews.

Plans are being made for a memorial service.