Aug 032017

Robert (Bob) Teghtsoonian was not only a founding member of the International Society for Psychophysics. From the very beginning, his continuous and lively engagement in the progress of the Society was outstanding: No one else had a stronger formative influen

ce on the ISP. It was one of his major concerns to encourage young scientists and to facilitate their integration into the scientific community. Bob never put himself at the center of things. And as everybody experienced his honest interest in people and their ideas, people around him felt secure and indeed were. Bob had the uncanny ability to create an atmosphere for open and unprejudiced exchange of ideas. Whatever the occasion, he always found the right words, the right wine, and the right humor along with his inimitable welcoming smile. We experienced much of this atmosphere at the Fechner Days. I also believe it was largely due to his efforts that the Fechner Days did not degenerate into vanity but remained one of the very few academic meetings which facilitated a personal exchange of thoughts from an equal stance in an accepting atmosphere. We will miss his constant attentiveness and support, his refreshing contributions and scientific impulses.

Text: Fritz Müller

To sign a Guest Book or express condolences you may go to:

Fechner Day 2017

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Feb 072017

The 33rd annual meeting of the international society for Psychophysics will be held in Fukuoka, Japan, 22-26 October 2017. Please note down the key dates of the conference:

  • Friday, 7 April 2017: Deadline for symposium proposals.
  • Friday, 5 May 2017: Deadline for submission of free talks, posters, and stipend applications.
  • Friday, 30 June 2017: Deadline for submission of proceedings manuscripts.
  • Friday, 21 July 2017: Deadline for early registrations.
  • Friday, 22 September 2017: Deadline for registrations.

See more information at the official website.

Fechner Day 2016 Info

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Jan 172016

The following PDF is Irina Skotnikova’s PowerPoint presented at Quebec, in which you may find useful information regarding to Fechner Day 2016 in Moscow.

FD2016 in Moscow

Fechner Day 2016, Moscow, Russia (15th-20th August)

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Jan 122016

Fechner Day 2016 – the 32nd Annual Meeting of the International Society  for Psychophysics 

 First announcement and call for papers

Dear friends and colleagues,

Happy New Year and invitation to visit Moscow in 2016!

We are pleased to send you the 1st announcement on Fechner Day 2016.

The 32nd meeting of the International Society for Psychophysics (ISP) will be held in Moscow, Russia, 15th – 20th of August, 2016.

You are invited to join us in Moscow, capital of Russia, founded in 1147 and full of famous historical and remarkable places, for Fechner Day 2016.

Please bookmark the conference’s website at http:/ and visit frequently for updates.

Venue  Continue reading »

William M. Petrusic, 1939-2014

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Jul 062015

Craig Leth-Steensen*

Carleton University, Canada



Our very distinguished and long-standing member, Professor William (“Bill”) M. Petrusic has left us. He died on Dec. 12, 2014, at the age of 75. He is survived by his wife Elaine and his three children, Michele, Michael, and Christopher. Bill co-hosted Fechner Day 2012 in Ottawa, Canada, which sadly was his last appearance at the annual ISP conference.

Born in Hazeldell, Saskatchewan, on May 18, 1939, Bill received a BA in psychology from the University of British Columbia in 1961, an MA in mathematics from the University of Michigan in 1963, and a PhD in psychology from the University of Michigan in 1968 (where he was supervised by Clyde Coombs). After a stint at the University of British Columbia, he joined the Psychology Department at Carleton University in Ottawa, Canada as a professor in 1970 (eventually becoming a Distinguished Researcher and Professor Emeritus in 2004) where he remained until his untimely passing.

Bill’s body of scientific work encompassed (exactly) 50 publications that addressed numerous issues of key importance to psychophysical and psychological researchers. His early published research focussed on the scaling of response time latencies and the study of short-term memory. In the late 70s, Bill published a large number of studies with his student Don Jamieson that dealt with important issues within such areas as duration judgement, preference judgement, and symbolic magnitude judgment (where, hopefully, the major aspect common to all of that work is self-evident). The late 80s and 90s led to a second large body of publications co-authored by another prolific student and eventual close colleague and friend, Joe Baranski. This period yielded seminal work on the semantic congruity effect, memory psychophysics, and the rendering of confidence. Finally, during the last 10 years, Sam Shaki and myself co-authored a number of studies with Bill that served to provide a wealth of novel results pertaining to both the semantic congruity effect and the spatial-numerical association of response codes (or SNARC) effect.

Bill has left behind an enduring legacy, both as a scientist and person, which a great number of the students he has mentored over the years would love to be able to emulate. His dedication to basic scientific work and the development of theory in mathematical terms inspired the people he collaborated with and solidified a place for him in the field as a serious and important researcher. I know that I, along with many others, will dearly miss hashing out research designs and theoretical standpoints with Bill (in addition to numerous discussions surrounding the merits of various 60s-era musical performers).

Keywords: unfolding; stochastic; Dylan; Hays; memory; TOE; reference point; power law; mental rotation; feedback; counting; transitivity; analogue; difference threshold; CVC; cross-over; speed-accuracy; latency-probability; discrete accumulator; slow-and-fast guessing; hard-easy; calibration; context; evidence accrual; comparative instructions; mental number line


* E-mail:

William M. Petrusic (1939-2014)

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Apr 172015

Craig Leth-Steensen and Jordan Schoenherr Carleton University, Ottawa

Steven Carroll
St. Mary’s University, Halifax

William M. (“Bill”) Petrusic received a BA in psychology from the University of British Columbia in 1961, an MA in mathematics from the University of Michigan in 1963, and a PhD in psychology from the University of Michigan in 1968 (where he was supervised by Clyde Coombs). After a stint at the University of British Columbia, he joined the Psychology Department at Carleton University in Ottawa, Canada as a professor in 1970 (eventually becoming a Distinguished Researcher and Professor Emeritus in 2004) where he remained until his untimely passing. Bill was longstanding member of the International Society for Psychophysics and recently served as its Treasurer from 2006-2012.

Throughout his career, Bill had a profound influence on countless students and colleagues. Indeed, Bill was responsible for both introducing his students to real psychological science (i.e., psychophysics) and then encouraging them to become fully engaged in this great field. Undoubtedly, each one of the individuals that he mentored feels eternally grateful that they were able to cross paths with such a fountain of scientific knowledge (in Ottawa, Canada of all places). In dealing with and learning from Bill, one always felt directly connected to the rich history of both quantitative and empirical psychological inquiry (whether that be Thurstonian scaling or Münsterberg’s early study of reaction time).

Bill’s body of scientific work encompassed numerous key areas of research including the study of time-order error, symbolic comparison, memory psychophysics, confidence processing, the semantic congruity and spatial numerical association of response codes (SNARC) effects, as well as the psychophysical processes underlying judgement and decision making. Much of his work was dedicated to specifying basic psychological processes in mathematical terms. One enduring legacy of Bill’s will most certainly be that he can be regarded as champion of stochastic evidence-accrual modeling of decision making. Indeed, much of the work he performed over the last 25 years was dedicated to demonstrating that static models of responding in perceptual and cognitive choice tasks were invariably inferior to models which postulated a dynamic accumulation of information over time (such as his rather ingenious slow-and-fast-guessing counter model).

On a personal level, all would agree that Bill was an incredibly gracious and generous supervisor and friend whom others would go out of their way to spend time with. Dinners with him were to be looked forward to and remembered afterwards. Adventurous in life as well as science, Bill was always ready to go regardless of what kind of crazy endeavour was being cooked up for that evening. Apart from science, Bill loved music, wine, cooking, and his lovely and always supportive wife Elaine. Bill’s passing has left many of us with something missing in our lives that we will simply not be able to replace.

Jordan Schoenherr – Reflections on Bill Petrusic

Dr. Bill was a giant of a man both in stature and intellect. My first experience with Bill was as an undergraduate statistics student. His Bob Dylan quotes suggested to me someone with deep convictions and a wry sense of humour – someone that understood the pluralities of life. He showed this through kindness and decency toward each of his students, grappling with ethical questions and always endeavouring to do the right thing rather than what was convenient or conventional. I soon realized that Bill presented an exemplar that I could only hope to emulate imperfectly. Students, including myself, were the beneficiaries of his experience as he gave us the opportunity to try and fail without judgment or condescension, a method that emboldened each of us to be persistent in our pursuits. During my time with Bill as an undergraduate and Master’s student, I learned deeper lessons than research and experimental design. Through him, I came to know the virtues of academia and psychological science, something that is difficult to teach and even harder to learn. Given the probability of meeting someone like Bill, I am lucky for having had the chance to know him. He truly made a significant difference in my life.

Steven Carroll – Meeting Bill Petrusic

I have a lot of fond memories of Bill, and it is difficult to put into words the many ways that he has influenced both my personal and professional life. A student’s relationship with Bill did not end in his classrooms or in his lab. If Bill took you under his wing, it meant spending time socializing with him at conferences, in this home, and at the Pub. But with so many professional and social interactions to choose from, I would like to share the story of how I met Dr. Petrusic. I think that I learned just about everything that I needed to know about the man’s character during those first 15 minutes.

On September 11th, 2001, I was an undergraduate student, working full time and taking night classes at Carleton University. The news reports started rolling in from New York during my commute to work and, as I’m sure many of you will recall, the ceaseless flow of information grew more intense and more frightening as the day wore on. By the time I started making my way to school for my PSYC 3000 Advanced Statistics class, the ambient anxiety in Ottawa was palpable. Nobody knew who was responsible for the attacks. Nobody knew how the U.S. was going to react. The phrase “World War III” was being nervously passed around the classroom when I arrived. Absolutely everyone was certain that the class would be cancelled.

Into this atmosphere walked a Hawaiian-shirt clad, white-bearded, pony-tail sporting… well, if I’m being perfectly honest, “hippie” was the word that sprung to mind. We all quietly watched him settle in at the front of the classroom. The very first words spoken to me by Bill Petrusic were these: “I want you all to know that I am very aware of the day’s tragic events. I seriously considered cancelling class this evening. But, in the end, I decided that it was probably best for all of us if we just work through this together.” At this point he proceeded to administer an algebra test and informed us that we had 15 minutes to complete it before we moved on with the day’s lecture.

I don’t know how other people responded to his actions. I do know that by the end of the lecture I was feeling better, if a bit embarrassed that I’d forgotten how to divide one fraction by another. I also know that, from that day forward, EVERY time that I’ve been faced with any real stress or anxiety in my life, I’ve reached for a textbook and have tried to teach myself something

new. I’ve learned a lot from Bill, but I think the thing that I’ve learned best was the value of learning for learning’s sake.

I also know that I went on to do my Honours, Masters, and PhD work with Bill and that I pretty much decided to do so right after that first class. He was happy. He was generous. He was wise. He was a fantastic teacher. I miss him.

Douglas Vickers (1940 – 2004)

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Mar 302015

Stephen Link
University of California, San Diego

Douglas Vickers, age 64, died suddenly at his home in Adelaide, Australia, on October 31, 2004. He is survived by his wife Yvonne, children Marc and Anne, and six grandchildren. His impressive career as a theoretical psychologist, experimental scientist, and mentor to famous students spanned forty years. Held in the greatest esteem, his students refer to him as a teacher of unfailing sincerity who was generous and warm in his dealings with others.

Vickers’ graduated from Edinburgh University in 1961, and continued to an Honours BA Degree from Cambridge University where he placed first in of the Natural Sciences Tripos (Part 2). In 1967 he received his Ph.D. supervised by Alan Welford. In 1994 Cambridge honored him with its Sc.D. In 2000-2002 Douglas Vickers served as President of the International Society for Psychophysics.

Douglas’ scientific career began in earnest with the famous Shallice and Vickers (1964) paper “Theories and experiments on discrimination time” in volume 7 of Ergonomics. This important review of psychophysical models provided an English approach to a topic of deepening interest in Europe and the United States. His Ph.D. thesis “Visual discrimination and the perception of visual depth” (1967) continued his exploration of perceptual phenomena investigated by psychophysical means. Professor Malcom Jeeves, Head of the Psychology Department at Adelaide University, offered him a Position as Lecturer and Doug immigrated to Australia.

At the time Alan Welford championed investigations of models of the time taken to perform judgment tasks. In 1970 Vickers added new ideas to the ongoing scientific adventure in the paper “Evidence for an accumulator model of psychophysical discrimination.” The theory can be imagined as a stochastic development of Fechner’s theory of sensory representation and Thurstone’s idea of comparative difference. The simplicity of the theory is its charm: two stimuli, a single distribution of sensory differences (a la Thurstone), two accumulators, and two response outcomes. The beauty of the theory is the vast number of predictions made about response probability and response time. In a way, the two accumulators race to be the first to generate a response.

The 1976 meeting of Attention and Performance VII, offered Douglas an opportunity for an important advance in the accumulator theory. The title of the paper, “An adaptive model for simple judgment,” does not prepare one for the major extensions suggested and empirically evaluated. The two accumulator model is described and then a three category model is described to account for judgments of sameness and difference. The manner in which parameters of the theory adapt to experimental conditions is discussed. Then, in a stunning contribution to psychophysical theory, Vickers provided further theoretical investigations and elaborations that accounted for the third important measurement variable, response confidence. In his book “Decision Processes in Visual Perception” (1979) Vickers provided a broad survey and theoretical investigation of simple decision processes, confidence and adaptation, and complex decision processes. This monograph followed up Vickers’ previous paper (“Where Angell feared to tread: response time and frequency in three- category discrimination”, 1975) by proposing a theory of equal judgments that yielded a convincing account of much experimental data. With references to 538 important experimental and theoretical papers, this masterful treatment of decision processes merits the attention of modem scholars, and is one of the most important psychophysical publications in the 20th century.

Decades of investigations into the underlying mechanisms of human perception and cognition followed this propitious beginning. The following jointly-authored articles provide an impression of the many different ideas and applications of Douglas’ contributions: “Effects of alternating set for speed or accuracy on response time, accuracy and confidence in a unidimensional discrimination task” in 1982, “The accumulator model of two-choice discrimination in 1988, “Interoperative patient controlled sedation” in 1991, “Intelligence and visual and auditory discrimination” (1995), “Towards a dynamic constructionist model of memory,” (1996) “Memory capacity and intelligence,” ( 1997), “Never cross the path of a traveling salesman,” (1998), “Human performance on visually presented traveling salesman problems,” (2001 ), “Towards a generative transformational approach to visual perception,” (2001), “Decision making and memory,” (2001), and “The perception of minimal structures,” in 2003 – just a sampling of his wide-ranging scientific interests.

Douglas gave members of the International Society for Psychophysics (ISP) new ideas on a regular basis. His publications at the ISP meetings began in 1989 with “Stopping rules in discrimination models,” and continued with “Individual differences in the rate of accrual of information, the FAST (frequency accrual speed test) index,” (1990), “Confidence and memory in simple judgments,” (1999), “Decision making and memory: Predicting accuracy, response time and confidence on individual trials,” (2000), “Where does the balance of evidence lie with respect to confidence?” (2001), and “Confidence and time in three-category judgments” (2003).

He was the organizer of many scientific sessions including “Human Decision and Choice” at the Twelfth Annual Conference of the Australian Psychological Society (1977), “Decision and Control Mechanisms in Perception and Memory” at the XXIV International Congress of Psychology (1988), “Theoretical Modeling in Psychophysics ” at the Sixteenth Annual Meeting of the International Society for Psychophysics (2000), and “Confidence and Psychophysical Judgments” at the Nineteenth Annual Meeting of the International Society for Psychophysics (2003). He was a member of the Organizing Committee of the 29th Experimental Psychology Conference in Adelaide, Australia, (2002) and Organizer for the Twenty-First Annual Meeting of the International Society for Psychophysics to be held in Adelaide, Australia in 2005.

Beyond these major events Doug also provided the field with his capabilities as reviewer of journal submissions, grant” applications, manuscripts, conference submissions and professional appointments. He was a founding member of Non-linear dynamics, Psychology and Life Sciences and Editor, with P. L. Smith, of Proceedings of the XXIV International Congress of Psychology (Volume 2) entitled Human Information Processing: Measures, Mechanisms and Models. He reviewed articles for such major journals as Psychological Review, Journal of Mathematical Psychology, Acta Psychologica, Perception, Journal of Experimental Psychology: Human Perception and Performance, Psychonomic Bulletin & Review, Perception & Psychophysics, Memory & Cognition, Australian Journal of Psychology, Perceptual and Motor Skills, Personality and Individual Differences, and Nonlinear Dynamics, Psychology and Life Sciences.

I believe that, in appreciation of this remarkable life, we should celebrate Doug’s career – a career peopled by famous teachers, outstanding contributions to our science, memorable lectures, insight, wit, intelligence, esteem, and international recognition. We can celebrate his many contributions through our fond memories of a charming colleague, an excellent scientist, and, to so many, a very good friend.