Comments by TaShauna U. Goldsby Ph.D., Cynthia M. Kroger Ph.D., and David B. Allison Ph.D. (January, 2017)

In 1997, the New York Times carried a full-page obituary [1] of one Dr. Stanley Schachter, Professor Emeritus of Psychology, Columbia University. The obituary emphasizes that Schachter’s influence was profound and highlights his unique ability to gain important scientific insights from everyday experiences and place those experiences under the microscope of his science. In fact, the American Psychological Association named him as the 7th most influential psychologist of the 20th century [2].

One of us (DBA) encountered Schachter through the literature as an undergraduate student in the early 1980s. In a class titled “Human Emotion and Motivation,” the professor used Schachter’s book “Emotion, Obesity, and Crime” [3] as the central text, supplemented with several of Schachter’s original research reports. The central thesis of the course built on Schachter’s idea [4] that emotion consists of both a physiological component (i.e., ‘autonomic arousal’) and a cognitive labeling of that component (e.g., as ‘angry’). By this way of thinking, if an external stimulus alters one’s cognitions, even in the face of arousal, one’s emotional experience might change in turn. If external and cognitive factors can influence the emotional experience of physiological arousal, could cues in the environment alter the experience of other physiologic phenomena, such as those associated with hunger? The answer appears to be yes, and Schachter displays this with experiments characterized by ingenious ruses in everyday situations, a strategy that became his signature as an experimentalist. The studies were written up in a lively and compelling style. Years later, DBA had the opportunity to meet Dr. Schachter over lunch and found the man himself to be every bit as engaging as his writings.

In his classic paper published in Science in 1968 [5], Schachter reviews the current state of the literature and reports three key tests of whether internal and external cues differentially affect eating behavior in normal weight and obese subjects. Taken together, his findings suggest that when compared to non-obese subjects, the eating behavior of obese subjects is more affected by environmental cues (e.g., external time cues, presence of food) than physiological (e.g., hunger, emotional arousal, internal time cues). These experiments are as follows:

• 1) Effect of Food Deprivation and Fear: Schachter manipulated bodily state in normal weight and obese subjects by two means (i) food deprivation (empty vs. full stomach) and (ii) manipulating fear (calm vs. frightened state). Normal weight subjects ate fewer crackers when their stomachs were full compared to empty, whereas obese subjects ate at least as many, if not slightly more, crackers when full. Normal weight subjects ate fewer crackers when frightened, while fear had no effect on the number of crackers eaten by obese subjects.
• 2) Effect of Manipulating Time: Normal weight and obese subjects were left in a room with either a clock that ran at half normal speed or at twice normal speed. Obese subjects ate almost twice as many crackers when they thought the time was 6:05 pm versus 5:20 pm. Normal weight subjects ate fewer crackers at 6.05 pm, reportedly, so as to not spoil their dinners.
• 3) Obesity and Adjustment to New Eating Schedules: Survey data were obtained from lean and obese individuals who endured time zone changes while traveling overseas. Compared with normal-weight subjects, obese subjects were relatively insensitive to their putative internal time cues and more readily adaptable to the external time cues with respect to their eating.

This paper perhaps best epitomizes Schachter’s profound influence on the field of obesity research in the early days of scientific study. For one, Schachter’s theory is arguably one of the first behavioral theories of eating and obesity. Previously, the prominent psychodynamic approaches attributed obesity etiology primarily to individual mental characteristics established during early childhood [6-8]. This shift in focus allowed for experimentation in ways prior psychoanalytic theories did not. Furthermore, by demonstrating that obesity is not one-dimensional but instead can be influenced by both internal and external stimuli, his work helped launch the social-cognitive and environmental approaches to obesity research that followed, which considered both psychogenic and environmental influences on obesity-related behavior.

Schachter’s extraordinary creativity and commitment to the scientific method, as exemplified in this paper, was perhaps instrumental to his powerful legacy. His reliance on multiple experiments is beautifully illustrative of his heavy dependence on the hypothetico-deductive ‘circle’ method, in which an initial hypothesis leads to an experimental test, which in turn leads to a refinement of the hypothesis based on observed outcomes, and in which the newly refined hypothesis is placed back at the beginning of the cycle [9]. Moreover, Schachter’s methods were unusually interesting and provocative, which attracted a number of students. He used imaginative narratives to blind participants to study objectives, and tricks, such as manipulating the speed of clocks, to isolate research questions in simple ways. Many of his students including, for example, Peter Herman, Judith Rodin, Richard Nisbett, Lee Ross, and Neil Grunberg, went on to become major contributors to the obesity literature and some of the highest regarded investigators in the field [10]. Through the work of his students, who, perhaps to Schachter’s credit, had the intellectual acumen and scientific courage to disagree with their mentor, Schachter’s theory has since been challenged [11, 12] and further extended into restraint theory [13, 14]. Dr. Rodin went on to become the first permanent female president of an Ivy League Institution and is current president of The Rockefeller Foundation, and Dr. Herman’s dietary restraint offered one of the first testable theories of eating disorder etiology, and his scale remains a regular tool for measurement [15].

Schachter’s isolation of extrinsic factors that influence the eating behaviors seen with obesity arguably paved the way for the era of research on the social and environmental factors of obesity etiology that followed. During the late 1980s, the psychological study of obesity shifted from a largely individual social-cognitive focus to one in which population-level environmental factors (i.e., external stimuli that presumably promote obesity) interacting with genetic and biological factors [16, 17] came to be seen as having greater importance. A leader of this thinking was (and remains) Dr. Kelly D. Brownell, who has supported his work with Schachter’s work [18] and co-wrote books with Judith Rodin. Brownell is credited with coining the phrase “toxic food environment,” [19] which attributes much of the difficulty individuals have with leading a healthy life to an environment of readily available and heavily marketed inexpensive, energy dense foods. Schachter’s identification of the externality trait helps explain which individuals would be susceptible to these environmental influences.

Although many of Schachter’s influential writings have “aged” past the point of being commonly cited as primary references, for those who know his work, his influence remains palpable. Interdisciplinary investigations that control or test for the differential effects of external versus internal stimuli on eating behaviors are not uncommon and are likely to ring bells. For instance, Dr. Brownell went on to develop the first food-addiction scale that controls for impaired self-identification skills (i.e., awareness of internal stimuli) commonly seen in those who are dependent [20]. More directly, a recent report names Schachter’s influence by stating that the aim of the trial was to “evaluate the feasibility, acceptability, and initial effectiveness of a novel treatment grounded in Schachter’s externality theory targeting food cue reactivity and satiety responsiveness with obese adults who binge eat” [21]. Schachter’s work continues to be a starting point for analyses of the complex interplay among external stimuli, physiological responses, and cognitive responses. This influence is seen today, for example, in conceptualizations of interactions between our microbiota and our macroeconomics, between our genetic makeup and our cultural and community environments, and many others – all harkening back to his observations of the key interplay between the internal and external and their impact on behavior.

References