David J. Murray

Charpentier (1891) : On the size weight illusion

This paper offers background for an English translation of an article originally published in 1891 by Augustin Charpentier (1852–1916), as well as a summary of it. The article is frequently described as providing the first experimental evidence for the size—weight illusion. A comparison of experiments on the judged heaviness of lifted weights carried out by Weber (1834) and by Charpentier (1891) supports the view that Charpentiers work deserves priority; review of other experimental studies on the size-weight illusion in the 1890s suggests that the idea that the illusion depended on “disappointed expectations,” especially with respect to speed of lift, became dominant almost immediately following the publication of Charpentiers paper. The fate of this and other ideas, including “motor energy,” in 20th-century research on the illusion is briefly described.

A perspective for viewing the history of psychophysics

Fechners conception of psychophysics included both “outer psychophysics” the relation between stimulus intensity and the response reflecting sensation strength, and “inner psychophysics” the relation between neurelectric responses and sensation strength. In his own time outer psychophysics focussed on the form of the psychophysical law, with Fechner espousing a logarithmic law, Delboeuf a variant of the logarithmic law incorporating a resting level of neural activity, and Plateau a power law. One of the issues on which the dispute was focussed concerned the appearance of contrasts if the overall illumination was increased or decreased; another issue was the question of whether a sensation of a “just noticeable difference” established for one value of a sensory dimension appeared the same for a value elsewhere on the dimension. The development of “inner psychophysics” led through the works of Delboeuf, Solomons, Jastrow, and Thurstone to modern signal detection theory. A third line of research, devoted to the question of what was meant by the “measurement” of sensation strength, stemmed from the criticism of Fechners work by von Kries (1882) and others. Although a valid body of science could be built up without the intervening variable called “sensation strength,” such a science might be a cumbersome representation of reality. When an optical contrast is set up, and its overall illumination is increased or decreased, subjective contrasts involving medium levels of lightness vary little as illumination varies (as a power law based on sensation ratios or a logarithmic law based on sensation differences predict), but subjective contrasts involving extreme levels of lightness might be subject to the effects of other variables.

E.H. Weber on the Tactile Senses

Part 1 De Tactu: summa dotrinae de tactu main findings on the tactile senses. Part 2 Tastsinn und Gemeingefuehl: on the conditions under which sensations are referred to external objects on the sense of touch in particular common sensibility - coenaesthesis.

Level of articulation and short-term recognition following brief probe delays

Subjects saw lists of three, four, five, or six digits; at the same time, they said them aloud, read them silently, or spoke the alphabet aloud (articulatory suppression). Recognition memory was examined with a probe presented 170 msec after the last item. Strong recency effects were obtained, with the serial position functions for the longer list lengths being parallel and linear; it is suggested that the linear set-size function frequently found in this paradigm can be predicted from parallel serial position functions. It was also found that, although errors increased following articulatory suppression, mean reaction times did not. A theory is put forward that articulatory suppression affects registration in memory for some items but does not affect the recognition time required for other items in the list; on the other hand, items early in the list suffer a loss of discriminability, due to the presence of later items, which is reflected in slower recognition times.

Herbart's mathematical psychology.

J.F. Herbart (1824/1890b) provided a mathematical theory about how mental ideas (Vorstellungen) in consciousness at Time 1 (T1) could compete, possibly driving 1 or more Vorstellungen below a threshold of consciousness. At T1 a Vorstellung A could also fuse with another, B. If at a later T2, A resurfaced into consciousness, it could help B to re-resurface into consciousness. This article describes the historical and mathematical background of Herbarts theory, outlines the mathematical theory itself with the aid of computer graphics, and argues that the theory can be applied to the modern problem of predicting recognition latencies in short-term memory (Sternbergs task; Sternberg, 1966)

Circadian Variation in Radiology

Circadian variation in radiological performance was examined by recording observers saccadic eye movements as they searched for pulmonary nodules on chest radiographs at 3 times of the day. Conventional R.O.C. analysis yielded no evidence of circadian variation. However an alternative analysis incorporated eye position information upon nodule detection and demonstrated a drop in sensitivity after lunch. Eye movement parameters were also examined for time of day variation. The results are discussed with regard to current theories of circadian variation. It is argued that the findings demonstrate a strategy change over the day and implications for radiology are considered.

Charpentier's Papers of 1886 and 1891 on Weight Perception and the Size-Weight Illusion

The French physiologist Augustin Charpentier (1852–1916) published the first accounts of the size-weight illusion—the observation that if two objects differ in size but have equal mass, the smaller will feel heavier when lifted. In the current paper, translations are presented of Charpentiers much-cited 1891 paper on weight perception and the size-weight illusion, and his little-known brief 1886 paper which contains the earliest experimental data on the illusion. Charpentier explained weight illusions in terms of the sense of effort involved in lifting the object and the contrast with the expected effort. Modern research shows that people quickly adapt and use the appropriate force to pick up objects, but the illusion persists even when appropriate force is used; expectations therefore affect the perceptual system more strongly than the motor system.

Conflicts and missed signals in psychoanalysis, behaviorism, and Gestalt psychology.

At the turn of the 20th century, European psychologists found themselves in conflict situations with respect to the role that private mental states should play in a scientific psychology. Out of this conflict arose 3 of the best-known schools of the 20th century: psychoanalysis, behaviorism, and Gestalt psychology. Each of these schools is discussed with respect to two characteristics. First, the authors discuss the attitude of each school on the meaning of the word unconscious as it was understood around 1900. Second, the authors discuss the influence of each school on the reception accorded to books written around 1900 espousing viewpoints that did not cohere with the schools beliefs. Such books may be considered missed signals in the history of psychology. Hits associated with each school are also highlighted.

A grouping interpretation of the modality effect in immediate probed recognition.

In a series of experiments on immediate probed recognition for eight 3-digit numbers, it was shown that if the target modality involved auditory components and the effect of the similarity of the modality of the probe to that of the targets was controlled, unequivocal evidence was obtained for an auditory superiority effect (modality effect) for hit rates for the final items of the list. Moreover, false-alarm rates were significantly lower following targets with an auditory component than they were following silently seen targets. It is argued that this pattern of hits and false alarms is consistent with the idea that targets that have an auditory component yield memory representations that are better grouped as units than are those for targets that are only silently seen; in particular, if a new probe has a first digit that accidentally matches the first digit of a target item, it is more likely that the subject will mistakenly identify this new probe asold (give a false alarm) if the target has only been partially encoded because it was only silently seen.

The Psychophysics of J-R-L Delboeuf (1831–1896)

Delboeufs writings on psychophysics are little known nowadays. The object of this paper is to describe the psychological contributions of this eminent Belgian psychologist of the second half of the 19th century. A true pioneer of experimental psychology, his work on psychophysics began in 1865 at the University of Gand (Ghent) but was not published until 1873 and following years. His work in this area is characterised on the one hand by the adoption of a logarithmic law relating sensation strength to stimulus strength, but which differed from that of Fechner; and on the other hand by the utilisation of a psychophysical technique based on brightness contrast (now called the ‘bisection method’). Even though Delboeuf was classified by Fechner in his later writings as an opponent of his beliefs, Delboeuf was nevertheless one of his least-virulent critics and the only psychologist of that era to have adopted a logarithmic law. Delboeufs work is not only of historic interest; his original ideas possess sufficient interest for present-day psychophysicists to reexamine them.