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Human Thermoregulation System and Comfort
Published in Guowen Song, Faming Wang, Firefighters’ Clothing and Equipment, 2018
Psychophysical laws were proposed to correlate sensory-related stimuli and perceived sensation. The basic assumption of psychophysical laws is that such correlations could be expanded to any type of sensation. Fechner et al. (1966) defined sensation perception as “outer psychophysics” and “inner psychophysics” and raised a question: Is there a universal law that could explain how we subjectively sense the world? They believed that general laws exist for “inner psychophysics” (Johnson, Hsiao, & Yoshioka, 2002). Weber–Fechner law incorporates two findings from the work of Weber and Fechner. Weber’s finding indicated that the just-noticeable difference (JND), that is, sensitivity of a stimulus, would be proportional to the magnitude of the stimuli. Fechner stated that there is a relationship between stimulus intensity and sensation perceived by the subject, with JND as the connecting factor. Based on the above, Weber–Fechner law describes this relationship as a logarithmic function, while later Stevens’s power law was proposed to describe the relationship as a power function (Stevens, 1957, 1961). In comparison with the mentioned psychophysical laws with regression models, it is found that Stevens’s power law has the highest predictive accuracy (Hu, Chen, & Newton, 1993; Li, 2005; Mazzuchetti, Demichelis, Songia, & Rombaldoni, 2008; Rombaldoni, Demichelis, & Mazzuchetti, 2010).
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Published in Carl W. Hall, Laws and Models, 2018
STELLAR STARS, LAWS OF; OR LAW OF STELLAR STRUCTURE The laws conform to the following four principles, often represented by differential equations: 1. Total mass interior to the radius is the sum of the mass in each interior shell, which is the product of the shell volume and mass density. 2. A shell's mass produces an increase in gas pressure beneath it equal to its weight per unit area (the product of its density, thickness, and the acceleration of gravity). 3. A temperature difference across a shell results in an energy flow (luminosity per unit area) controlled by the opacity of the material. 4. The luminosity must be the sum of the energy released within the radius by all interior shells. Keywords: energy, flow, mass, opacity, pressure, shell(s) Sources: Brown, S. B. and Brown, L. B. 1972; Maran, S. P. 1992; Travers, B. 1996. STENO--SEE SUPERPOSITION, LAW OF (GEOLOGY) STERNBERG LAW (1875) The decline in size of elastic particles transported downstream is proportional to the weight of the particle in the water and to the distance it has traveled, or to the work done against friction along the bed: W = Woe–as where W = weight at any distance, s Wo = initial weight of particle a = coefficient of size reduction Keywords: friction, size, particles, work STERNBERG, Hilgard O'Reilly, nineteenth century, German engineer Sources: Gary, M. 1972; NUC. STEVENS PSYCHOLOGICAL LAW (1951); STEVENS POWER LAW A power law stating that equal stimulus ratios produce equal subjective ratios, as represented by: = k Sn where = psychologic magnitude S = stimulus magnitude k, n = constants on log-log scale, with n the slope of a straight line, and the exponent ranges from 0.3 to 4.0
Visual psychophysics and color appearance
Published in Sharma Gaurav, Digital Color Imaging Handbook, 2017
Garrett M. Johnson, Mark D. Fairchild
The power function relationship between physical and perceptual scales has become known as Stevens’ power law. It has been used to model many perceptions in color imaging, such as the prediction of lightness in the CIELAB color space. Details on that will be explained later in the chapter.
The level of measurement of trust in automation
Published in Theoretical Issues in Ergonomics Science, 2020
Jiajun Wei, Matthew L. Bolton, Laura Humphrey
The psychophysics that have been subjected to level-of-measurement analyses relate to Stevens’ power law (Stevens 1956), which links physical stimulus intensity to its perceived intensity. To produce a power law, humans make ratio judgments about the relative magnitudes of different stimuli represented on a ratio scale. Prominent researchers have expressed scepticism that humans are capable of making true ratio judgments (Laming 1997). Attempts have been made to check this (Ellermeier and Faulhammer 2000; Zimmer 2005) by assessing whether judged ratio differences between measured physical stimuli follow multiplicative and commutative properties. These found that judgments satisfied the commutative property, but not the multiplicative one. While this is sufficient to indicate that humans can make ratio judgments in power law experiments, it would be more convincing if both properties held (Narens 1996). Further, Bolton (2008) found that psychophysical power laws could be fit to ordinal numbers generated in computationally simulated power law experiments.
Equivalent magnitude-dependent discomfort under vertical vibration up to 100 Hz
Published in Ergonomics, 2022
Jiewei Lin, Meng Li, Zefeng Lin, Jian Wang, Xiangde Meng, Junhong Zhang
The growth rate of discomfort is the exponent in the Stevens’ power law indicating the rate of the subjective feelings with respect to the magnitudes of physical excitations. It is found that the growth rate of discomfort (see Figure 2) show significant frequency-dependence.