Jan 172015

Larry Marks
John B. Pierce Laboratory and Yale University

A leader in sensory psychophysics during the second half of the 20th century, Joe Stevens died unexpectedly but peacefully at his home on February 7, 2014, three weeks shy of his 85th birthday. Born and raised in Grand Rapids, Michigan, Joe attended Calvin College, where courses in psychology and philosophy, as well as in his major subject, biology, sparked an indelible interest in human sensation and perception. After receiving his undergraduate degree in 1951, Joe studied vision with S. Howard Bartley, taking a masters degree in psychology at Michigan State University in 1953 before moving on to doctoral studies at Harvard. This move marked the start of a thirteen-year collaboration with S. S. (Smitty) Stevens, first as a student and later as a faculty colleague in Harvard’s psychology department.

Arriving in 1953, Joe was present at the creation, so to speak, for it was in that year that Smitty first proposed a power function to describe how the magnitudes of sensory experiences in both hearing (loudness) and vision (brightness) relate quantitatively to the physical energy level of the external stimulus. Working in Smitty’s lab, Joe assiduously expanded on these early results, reporting his own findings on brightness and loudness in his doctoral dissertation of 1957 and in a series of major articles published between 1958 and 1966. During this period, Smitty and Joe also worked on a monograph, The Dynamics of Visual Brightness, which focused the lens of the new psychophysics on visual perceived intensity. They completed a draft of the manuscript in 1960 but – alas! – never published it, although they distributed it to researchers in vision and in psychophysics. According to a Google search (December 2014), the unpublished manuscript was cited more than 30 times, most recently in 2004.

Joe’s research during this early stage of his career took two main directions: One was to apply the methods of psychophysical scaling to a variety of sensory systems: not only vision and hearing (the subjects of his doctoral dissertation), but other modalities as well, including warmth and cold. Importantly, Joe created a method of cross-modality ratio-matching, reported in his dissertation and cited by Smitty in the same year, 1957, one year before Smitty began his own initial efforts at (conventional) cross-modality matching.

The second direction, and arguably one of his most important contributions, was to use methods of psychophysical scaling to illuminate fundamental sensory processes. This is evident in early findings first reported in his doctoral dissertation and then expanded in a seminal article (J.C. Stevens and S.S. Stevens, 1963) showing how light adaptation affects the perception of brightness. Joe and Smitty quantified the effects of adaptation in terms of changes in the three parameters (exponent, multiplicative constant, and threshold) of a generalized power equation. Demonstrating the utility of psychophysical scaling methods as tools for understanding sensory processes would leave an indelible mark on many subsequent researchers, including this biographer.

In the fall of 1966, Joe left Harvard to establish and lead the psychology-psychophysics division at the John B. Pierce Laboratory, an independent, non-profit institution affiliated with Yale University. Joe held the title of Fellow at the Pierce Laboratory and, at the time of his death, Senior Research Scientist in psychology at Yale. Under Joe’s leadership, the division quickly grew, as Larry Marks and then Ellie Adair, Bill Cain, Linda Bartoshuk and others joined the research group. Over the years, some stayed, some left, but by 1999, when Joe published the last article bearing his name, the number of publications from the division that he had created surpassed 500.

In 1966, when Joe arrived at the Pierce Laboratory, much of its multidisciplinary research focused on body temperature regulation, and Joe quickly began to expand his early work on warmth and cold by studying thermal perception, especially the roles of spatial summation, temporal summation, and adaptation. But, taking another lesson from Smitty, Joe continued to think of himself as a ‘sensory generalist,’ working from time to time on issues in vision and hearing, and expanding his main research endeavors to include taste and smell as well as warmth and cold.

Over the last two decades of his career, Joe’s research increasingly emphasized changes in sensory systems as people age, much of it conducted under a 10-year Merit award from the National Institutes on Aging of the NIH. Hearing tends to worsen with age. So too can vision. But aging takes a toll on other senses too: on touch, taste, and, especially, olfaction – the sense of smell – this being evident both in the great decline in sensitivity to odorants that are sniffed (orthonasal olfaction) and to volatile chemical components perceived as flavors when foods and beverages are taken into the mouth (retronasal olfaction). The consequences of olfactory decline can be serious. Joe showed, for instance, that older individuals, and older men especially, often cannot detect the malodorous agent that is added to natural gas to serve as a warning in gas leaks.

A leading figure in modern psychophysics, Joe was teacher and colleague to many. Those fortunate enough to study with him or work with him benefited not only from his intellectual acuity and creativity, but at least as much from his mentorship, his friendship, and his generosity of spirit.

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