Shape constancy

One of the most striking aspects of perception is constancy. Constancy refers to how our perception of objects remains the same despite changes in their image on the retina. Constancy is seen in the perception of a number of different properties of objects such as size, shape, color, and orientation. We will discuss only size and shape constancies. 

Shape constancy refers to an object s shape being perceived as remaining the same despite being viewed from different perspectives with different shapes being projected onto the retina. A circular shape such as a pie on a table for example, is still perceived as circular even when you sit down at the table and perceive it from the side. This is despite the fact that circles viewed from the side produce not circular but elliptical images on the retina. 

Of the various geometric parameters associated with molecular shape, the one most nearly constant from molecule to molecule and most nearly independent of substituent effects is bond length. Bond lengths to carbon depend strongly on the hybridization of the carbon involved but are little influenced by other factors. Table 1.2 lists the interatomic distances for some of the most common bonds in organic molecules. The near constancy of bond lengths from molecule to molecule reflects the fact that the properties of individual bonds are, to a good approximation, independent of the remainder of the molecule. 

Whilst the shape of a propellent grain determines the constancy or otherwise of the burning process, the actual time occupied depends on the grain dimensions. The term web thickness is used to denote the shortest distance in a grain through which burning can go to completion it is... 

The plot Ge/Te vs. vg/Te yields then A from the slope and from the intercept (Langley-Greassley plot). The applicability of this plot will be commented on below and it will be shown that this plot is not very suitable for endlinked networks with varying as a function of the conversion or molar ratio of components. The similarity between the shapes of v e and Te and the resulting relative constancy of /Tg is the reason. The other disadvantage of analysis of experimental data using Eq.(1) or (5) based on the difference between the values Ge and Ve is the sen-... 

Lead profiles in Lake Constance (Summer 81 data Sigg, 1985) and in the Pacific Ocean (1981 data Schaule and Patterson, 1981). The similar shape of these profiles despite the difference in length scales (kilometers for the ocean and meters for the lake), illustrates the influence of the atmospheric deposition on the upper layers and the scavenging of Pb(II) by the settling particles. 

An especially important aspect of our protocol is the collection and analysis of data over different time spans. 18 This is done using the same number of channels to collect about the same number of photons, but with different channel delays. Typically, data on four time spans, 0 to 16-20 ns, 0 to 35 10 ns, 0 to 65-80 ns, and 0 to 120-130 ns, are collected and analyzed. In our experience, the. constancy of the best-fit model parameters with variation in time span is the most sensitive and reliable test for the shape of the model function. 

The discussion directly following Eq (6) provides a simple, physically reasonable explanation for the preceding observations of marked concentration dependence of Deff(C) at relatively low concentrations. Clearly, at some point, the assumption of concentration independence of Dp and in Eq (6) will fail however, for our work with "conditioned" polymers at CO2 pressures below 300 psi, such effects appear to be negligible. Due to the concave shape of the sorption isotherm, even at a CO2 pressure of 10 atm, there will still be less than one CO2 molecule per twenty PET repeat units at 35°C. Stern (26) has described a generalized form of the dual mode transport model that permits handling situations in which non-constancy of Dp and Dh manifest themselves. It is reasonable to assume that the next generation of gas separation membrane polymers will be even more resistant to plasticization than polysulfone, and cellulose acetate, so the assumption of constancy of these transport parameters will be even more firmly justified. 

The central point of this hypothesis that functions VT(v) and E(v) are temperature-independent is actually based on apparent constancy of water density over the temperature range under study and this statement gives an important ability to predict spectrum shape at any temperature from the experimental IR or Raman spectra recorded at the only one temperature. 

Although these approaches demonstrate the important role of the drug material s surface and its morphology on dictating the dissolution profile, they still suffer from limitations regarding the shape and size distribution of particles as well as the assumptions on the constancy of the diffusion layer thickness S and the drug s diffusivity V throughout the process implied in (5.5), (5.6), (5.7), and... 

If the properties of one ion affect those of the other when they interact, an iterative approach has to be taken until constancy of intermolecular energy is obtained. This is because the dipoles induced in the ions exert counter fields upon the surrounding ions and the resulting change in shape modifies the values obtained for a system conceived as a sum of attractive and repulsive forces of unchanging spherical ions. If such a counter field can be calculated, then equations such as (5.9) can be used without the introduction of a dielectric constant in the Coulomb attractive term. Thus, dielectric constants are empirical devices that make an allowance for counter fields and forces in electrical systems. 

The stability surfaces depicted in Figure 3 are quite simple in shape. As mentioned previously (during discussion of Stability Profiles), a situation may be reached where some of the ligand species are almost totally complexed while the others are largely uncomplexed. This can lead to a temporary constancy of the stability function over an intermediate range of ratios,... 

We have previously called attention to what appears to be a law of constancy of shape in strictly isoelectronic species. This is particularly well illustrated by the F j-E-Feg angle (given in parentheses) in the series XeF, (79 (1)°),... 

A completely different approach (11), which takes into account the actual shape of the established gradient of the focusing forces in the direction of jc-coordinate, leads to purely analytic solution without a priori assumption of the constancy of the gradient in the domain of the focused zone (J5, 16) and without approximation by a series 17, 18),... 

Perceptual constancy is one of the hallmarks of the field of perception, for it strongly indicates that visual perception involves more than the direct registration of the retinal image in the brain. Without perceptual constancy the world would be perceived as a booming blur of chaotic confusion in which the sizes, shapes, and colors of objects would be constantly shifting. Thus it can be seen that perceptual constancy serves an important adaptive fimction. 

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