Weber, the first person who may be categorized as a psychophysicist, was professor of anatomy and physiology at Leipzig from 1818 until his death. The University at Leipzig became the dominant institution for both the psychophysics movement and the emergence of a psychology modeled after the natural sciences. Weber's contributions were essentially limited to an exhaustive investigation of the sense of touch. Nevertheless, he secured a methodological orientation that seemed to demonstrate the possibility of quantifying mental or psychological
operations. His major work in psychology, De Tactu: Annotationes Anatotnicae et Physiologitie (On Touch: Anatornical and Physiological Notes), was published in 1834 and contained extensive experimental work. He distinguished three manifestations of the sense of touch: temperature, pressure, and locality sensations. Temperature was dichotomized into positive and negative sensations of cold and warm, which Weber felt were analogous to the light and dark sensations of
vision. In his investigations of pressure, Weber developed a methodological innovation known as the two-point
threshold. Briefly, he used a compass with two points and attempted to measure cutaneous sensitivity by the smallest detectable distance between the two points that could be sensed by a subject. Weber found that this threshold of detectable difference between the two points varied with the places of stimulation, a variation he explained by postulating differential densities of nerve fibers underlying the skin's surface. This method led him to a study of weight discrimination and eventually to the
formulation of -Weber's Law," named for him by his colleague Gustav Fechner, who is considered below. Weber found that the smallest detectable difference between two weights can be expressed by the ratio of thc difference between the
weights, and this ratio is independent of the absolute values of the weights. He extended his research to other senses and found general validity for the ratio of the smallest detectable difference between two stimuli. The last touch sensation, locality, was viewed by Weber to be more than a sensory dimension. Rather, he felt locality was more dependent on perception, which he interpreted as mental
activity. Weber succeeded in using a quantifiabie approach to sensations, an approach that was adopted by his successors.
However, in his interpretation of mental action on these sensations, Weber relied on the prevailing philosophical system of
Germany-namely, Kant's views on the mind. In other words, Weber viewed perceptions as governed by mental categories of time and space, and he did not speculate further. |
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