Jan 252022

Martha Teghtsoonian

Robert Teghtsoonian (1932-2017) was born in Toronto, Canada, where his parents had emigrated from Armenia in the wake of the Armenian genocide and the First World War.1 Bob (as everyone called him) earned his bachelor’s degree and his master’s in psychology from the University of Toronto, his Ph. D. in the Department of Psychology at Harvard. There he met Martha (whom everyone calls Mimi); their marriage was the beginning of a life-long collaboration. At his death, he left his wife, his son Chris, and a niece and two nephews, Katherine, Brian, and David Teghtsoonian.

Bob tackled many research projects in psychology, and he often worked with collaborators. Among his first publications were a series of studies of activity in rats as a function of food deprivation and environmental stimulation, done with Byron Campbell2; they were followed by an investigation of activity in rats as a function of deprivation and incentive, with colleagues at the University of Pennsylvania.

At Harvard, his doctoral research was in verbal learning. He showed that mastering a list in a recognition task was dependent on the number of items from which the correct item must be selected. Trials to mastery increased with larger numbers of alternative items. However, the effect was entirely on retrieval, not on storage.3 He also provided an elegant demonstration of one-trial learning in individuals, showing that mastery of a single item occurred on a single trial.4

In 1970, he switched his attention to psychophysics. Always interested in practical applications of psychophysical techniques, he worked with Randy Frost to use magnitude scaling to assess fear of snakes in phobic subjects, as a function of distance from a boa constrictor displayed in a Plexiglas cage which was either uncovered or covered.5

With Birgitta Berglund and Ulf Berglund, Bob and Mimi undertook a study of magnitude of odor strength as a joint function of the intensity of the olfactory stimulus and the strength of sniff pressure, and showed that (contrary to previous assumptions based on physiological preparations) varying the flow rates produced by sniff pressure did not produce corresponding changes in odor strength. They proposed an odor- constancy model, in which sensed sniff pressure and sensed odor strength combined to produce invariance in odor strength.6

A series of studies on the effect of fatigue on perceived effort in a variety of activities was carried out in Gunnar Borg’s laboratory, with his advice and assistance. 7

With Georges Canévet, Bob and Mimi conducted a series of studies examining the phenomenon termed decruitment, a rapid decrease in loudness as an auditory signal continuously lessens in sound energy, as well as upcruitment, a rapid increase in loudness as an auditory signal continuously grows. In both cases, the change in loudness was greater than would be predicted from the magnitude scale for loudness. They extended the paradigm to visual area, and showed that decruitment occurred in that modality as well.8

Bob’s major work in psychophysics was elucidating the relationships among perceived magnitude of sensory signals, resolving power, and dynamic range. He first (1971) suggested, in On the Exponents in Stevens’s Law and the Constant in Ekman’s Law9that, on all sensory continua, measures of discrimination, measures of subjective rate of growth in intensity, and the range of sensitivity were governed by the same set of relations. He hypothesized that this might depend on a central magnitude monitor. In the succeeding four decades, a series of studies examined various objections to the model and showed how biases could be controlled.10 The culmination of this work, published in 2012, was The Standard Model for Perceived Magnitude: A Framework for (Almost) Everything Known about It.11 This paper explores two ideas. One is that the dynamic ranges of sensory continua are measurable (or estimatable) and, importantly, less susceptible to the biases attendant on the measurement of exponents. The second is the assumption that every dynamic range is equal in subjective magnitude to every other dynamic range. From these two ideas, it follows that an exponent is predictable from the dynamic range, as is the just-noticeable ratio, and that all just-noticeable ratios are subjectively equal. As the title of this paper suggests, the model provides at least a useful heuristic to summarize the state of our knowledge, and at best the basis of a research program to test its predictions.

Bob was one of the founding members of ISP, along with Mimi, Birgitta Berglund, Ulf Berglund, and Bert Scharf. He envisioned the society as one where membership was governed by an interest in psychophysics, where a graduate student giving a first presentation received the same attention as an eminent psychologist, and an eminent psychologist was met with the same critical attitude as a graduate student. He also hoped that as much time at meetings would be devoted to informal discussions as to formal presentations.

He corresponded widely with colleagues and was a frequent reviewer of manuscripts for a number of psychological journals.

Outside of psychology, his interests were also broad. He loved music–from Mozart, to Willie Nelson and Linda Ronstadt, to Stan Getz and the Modern Jazz quartet, with a special liking for gypsy jazz. He was an ardent fan of the Boston Red Sox. He followed American politics closely and became an American citizen so that he could vote in elections. With his wife and son, he travelled widely in Europe, but especially in France. He enjoyed good food and good wine, especially with good company. Perhaps most of all, he liked a good argument.

He loved games, both as a spectator and a participant. He believed that science was a team sport, and that it was the best game of all.

Selected References

1. Teghtsoonian, O. (Author) and Teghtsoonian, R. and Teghtsoonian, C. (Editors) From Van to Toronto: A Life in Two Worlds. iUniverse, 2003.

2. Teghtsoonian, R. and Campbell, B. A. Random activity of the rat during food deprivation as a function of environmental conditions. Journal of Comparative and Physiological Psychology, 1960, 53, 242-244.

3. Teghtsoonian, R. The influence of number of alternatives on learning and performance in a recognition task. Canadian Journal of Psychology, 1965, 19, 31-41.

4. Teghtsoonian, R. and Teghtsoonian, M. Discontinuities in recognition learning revealed by critical-trial analysis. The American Journal of Psychology, 1971, 84, 75- 84.

5. Teghtsoonian, R. and Frost, R. O. The effects of viewing distance on fear of snakes. Journal of Behavioral Therapy & Experimental Psychiatry,1982, 13, 181-190.

6. Teghtsoonian, R., Teghtsoonian, M., Berglund, B., and Berglund, U. Invariance of odor strength with sniff vigor: An olfactory analog to size constancy. Journal of Experimental Psychology: Human Perception and Performance, 1978, 4, 144-152.

7. Teghtsoonian, R., Teghtsoonian, M., and Karlsson, J.-G. The limits of perceived magnitude: Comparison among individuals and among perceptual continua. Acta Psychologica, 1981, 49, 83-94.

8. Teghtsoonian, R., Teghtsoonian, M., and Canévet, G. The perception of waning signals: Decruitment in loudness and perceived size. Perception & Psychophysics, 2000, 62, 637-646.

9. Teghtsoonian, R. On the exponents in Steven’s law and the constant in Ekman’s law. Psychological Review, 1971, 78, 71-80.

10. Teghtsoonian, M., and Teghtsoonian, R. Putting context effects into context. In Berglund, B. and Borg, E. (Eds.), Fechner Day 2003, 309-314. Larnaca, Cyprus: International Society for Psychophysics.

11. Teghtsoonian, R. The standard model for perceived magnitude: A framework for (almost) everything known about it. American Journal of Psychology, 125, 165- 174.

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