Psychophysics of Visceral Perception in Humans
Looking back on the theoretical considerations of this essay, it seems as though the claim to quantification would be the basic criterion of the acceptance of visceral afferent events among the validated special sensory phenomena, such as olfactory, visual, and auditive processes. To be sure, the psychology of special senses is deeply intermingled with phenomena of perceiving the learned pseudoreality, i.e., of detecting and identifying the well-known illusions and even hallucinations! Also, human subjects are unable to escape the influence of these mistaken perceptions. At the same time, however, the physiology and psychology of sensations and perceptions are subject to powerful and reliable tools that can separate misperceptions from true ones. Chief among these are the law of Fechner (1860/1966) and the signal detection approach (Swets, 1964). We have undertaken some trials seeking to strip away the subjective beliefs and socially learned symptom reports (seep. 161) from the objectively quantifiable percepts. It is our view that visceroception must fulfill the same criteria as, e.g., haptic sensitivity. In other words, viscerosensory functions must be subject to the laws of psychophysics, e.g., to the basic principle of Fechner (1860), namely Ψ = k·log Φ, in which both the internal experience Ψ and the physical stimulus Φ should be measurable. It is essential to mention here that instead of the logarithmic relations originally proposed by Fechner, nowadays we apply the power function proposed by Stevens (1975): Ψ = k· Φα in which the exponent a depends on the modality of the Φ stimulus applied. Quantification of the internal stimulus applied seems to be in most experimental and clinical cases less problematic, but the measurability of Ψ meets with several difficulties. Naturally the main obstacle is the lack of detectability of most visceral stimuli, which elicit nonreportable, unconscious behavioral or electrophysiological changes. The quantification possibilities and approaches of both components of the Fechner-Stevens principle are considered next.
KeywordsWarning Stimulus Rubber Balloon Visceral Afferents Visceral Perception Visceral Stimulus
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