The Effects of Illumination Level and Retinal Size on the Depth Stratification of Subjective Contour Figures

Perception ◽  
1984 ◽  
Vol 13 (2) ◽  
pp. 155-164 ◽  
Author(s):  
Drake R Bradley ◽  
Susan T Dumais
Keyword(s):  
Subjective Contour ◽  
Illumination Level ◽  
Retinal Size ◽  
Depth Stratification

Amodal Completion, Depth Stratification, and Illusory Figures: A Test of Kanizsa's Explanation

Perception ◽  
1992 ◽  
Vol 21 (3) ◽  
pp. 325-335 ◽  
Author(s):  
Franco Purghé ◽  
Stanley Coren
Keyword(s):  
Subjective Contour ◽  
Causal Factor ◽  
Amodal Completion ◽  
Logical Inconsistency ◽  
Indirect Measures ◽  
Depth Relationship ◽  
Depth Stratification

Subjective contours have been explained by Kanizsa as being a consequence of amodal completion of incomplete figures. According to the theory of amodal completion, figural incompleteness triggers the emergence of an illusory object superimposed on the gaps in the inducers, which in turn hide parts of the pattern, thus suggesting that the plane of the illusory object must always be seen to be above the plane of the inducers. A figure was created in which subjective contours are seen despite the fact that the perceived depth relationships run counter to that required by the theory of amodal completion. In four experiments, this depth relationship is confirmed by using direct and indirect measures which assess both registered and apprehended depth. By emphasizing a logical inconsistency in the explanation based on amodal completion, the results show that amodal completion, at least in Kanizsa-like patterns, cannot be considered as a causal factor for subjective contour figures.

One Million Direct Magnification Microscopy

1971 ◽  
Vol 29 ◽  
pp. 166-167
Author(s):  
J. A. Hugo ◽  
V. A. Phillips
Keyword(s):  
Electron Microscopy ◽  
High Resolution Electron Microscopy ◽  
Illumination Level ◽  
Level Of Detail ◽  
Photographic Emulsion ◽  
Low Contrast ◽  
Fluorescent Screen ◽  
Resolution Electron ◽  
Lattice Images ◽  
Electron Microscopes

A continuing problem in high resolution electron microscopy is that the level of detail visible to the microscopist while he is taking a picture is inferior to that obtainable by the microscope, readily readable on a photographic emulsion and visible in an enlargement made from the plate. Line resolutions, of 2Å or better are now achievable with top of the line 100kv microscopes. Taking the resolution of the human eye as 0.2mm, this indicates a need for a direct viewing magnification of at least one million. However, 0.2mm refers to optimum viewing conditions in daylight or the equivalent, and certainly does not apply to a (colored) image of low contrast and illumination level viewed on a fluorescent screen through a glass window by the dark-adapted eye. Experience indicates that an additional factor of 5 to 10 magnification is needed in order to view lattice images with line spacings of 2 to 4Å. Fortunately this is provided by the normal viewing telescope supplied with most electron microscopes.

THE EFFECTS OF INTERNAL PARTITION ON INDOOR DAYLIGHTING PERFORMANCE OF STUDENT RESIDENTIAL BUILDING IN IPOH, PERAK

2020 ◽  
Vol 7 (2) ◽  
pp. 1
Author(s):  
Khairul Azmi Mohamed ◽  
Asmat Ismail ◽  
Nur Azfahani Ahmad
Keyword(s):  
Residential Building ◽  
Illumination Level ◽  
Internal Partition ◽  
The Tropics

The installation of an internal partition has resulted in lowering the illumination level inside a building. Therefore, this study is intended to evaluate the effects of several internal partition layout on indoor daylighting performance in student residential rooms. Several options of internal partition were simulated using Climate Based Daylight Modelling (CBDM) to suggest the effective partition layout to overcome low daylighting level inside the room at the annual level. The findings indicate that the internal partition perpendicular to the window layout has been proven to have the highest annual daylight sufficiency in a student residential room in the tropics.

scholarly journals Effects of test experience, closed-arm wall color, and illumination level on behavior and plasma corticosterone response in an elevated plus maze in male C57BL/6J mice: a challenge against conventional interpretation of the test

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Hirotaka Shoji ◽  
Tsuyoshi Miyakawa
Keyword(s):  
Elevated Plus Maze ◽  
Plasma Corticosterone ◽  
Illumination Level ◽  
Test Battery ◽  
Lower Percentage ◽  
Behavioral Tests ◽  
Elevated Plus Maze Test ◽  
Maze Test ◽  
Plus Maze ◽  
Corticosterone Response

AbstractThe elevated plus maze test is a widely used test for assessing anxiety-like behavior and screening novel therapeutic agents in rodents. Previous studies have shown that a variety of internal factors and procedural variables can influence elevated plus maze behavior. Although some studies have suggested a link between behavior and plasma corticosterone levels, the relationships between them remain unclear. In this study, we investigated the effects of experience with a battery of behavioral tests, the wall color of the closed arms, and illumination level on the behavior and plasma corticosterone responses in the elevated plus maze in male C57BL/6J mice. Mice were either subjected to a series of behavioral tests, including assessments of general health and neurological function, a light/dark transition test, and an open field test, or left undisturbed until the start of the elevated plus maze test. The mice with and without test battery experience were allowed to freely explore the elevated plus maze. The other two independent groups of naïve mice were tested in mazes with closed arms with different wall colors (clear, transparent blue, white, and black) or different illumination levels (5, 100, and 800 lx). Immediately after the test, blood was collected to measure plasma corticosterone concentrations. Mice with test battery experience showed a lower percentage of open arm time and entries and, somewhat paradoxically, had lower plasma corticosterone levels than the mice with no test battery experience. Mice tested in the maze with closed arms with clear walls exhibited higher open arm exploration than mice tested in the maze with closed arms with black walls, while there were no significant differences in plasma corticosterone levels between the different wall color conditions. Illumination levels had no significant effects on any measure. Our results indicate that experience with other behavioral tests and different physical features of the maze affect elevated plus maze behaviors. Increased open arm time and entries are conventionally interpreted as decreased anxiety-like behavior, while other possible interpretations are considered: open arm exploration may reflect heightened anxiety and panic-like reaction to a novel situation under certain conditions. With the possibility of different interpretations, the present findings highlight the need to carefully consider the test conditions in designing experiments and drawing conclusions from the behavioral outcomes in the elevated plus maze test in C57BL/6J mice.

Влияние городских сооружений на формирование прилегающих фитоценозов

2019 ◽  
Author(s):  
Igor Dragutan ◽  
◽  
Irina Kolomiet ◽  
Anatolie Scurpelo ◽  
◽  
...  
Keyword(s):  
Dominant Species ◽  
Illumination Level ◽  
Demographic Structure ◽  
Seasonal Aspects

The influence of urban constructions of Orhei city on illumination level of adjacent phytocenoses was studied. It was established that increased shade of territory leads to shift of distribution maximum of concrete flora to arctic direction, distortion of seasonal aspects and changing demographic structure of dominant species populations.

scholarly journals Lightness constancy: Object identity and temporal integration

Psihologija ◽  
2008 ◽  
Vol 41 (1) ◽  
pp. 5-20 ◽  
Author(s):  
Suncica Zdravkovic
Keyword(s):  
Prior Experience ◽  
Temporal Integration ◽  
Illumination Level ◽  
Object Identity ◽  
Single Object ◽  
Lightness Constancy ◽  
Systematic Fashion ◽  
Target Values ◽  
Priming Paradigm ◽  
True Color

Studies of lightness constancy typically involve the comparison of two objects of the same shade that have been placed under different illuminations. In this study, we introduce factors such as object identity and immediate prior experience to measure the effect of these manipulations on constancy. In the first experiment, conditions sufficient to reproduce classical constancy failure (illumination difference, target values, articulation level) were determined. In the second experiment a lightness judgment was made for a gray target that was then seen to move into another illumination level for the second match. Motion was used in an attempt to stress the target?s identity. The shade was still judged significantly lighter when placed under the higher than under the lower illumination. Failure of constancy thus occurred even when object identity was not in question. In the third experiment a priming paradigm was used, to assess the strength of constancy: one shade would appear in one illumination level and another shade in the other illumination level. Motion was used to trick observers into thinking that only a single object was presented. The estimated shade varied as a function of the shade of the prime. In the last experiment, observers were asked to make another match when the object was removed from view: the match of its true color independent of illumination. The value of this match-from-memory was based on the value obtained in the higher illumination level. Taken together, the experiments show that through object identity, immediate prior experience can influence lightness in systematic fashion.

scholarly journals Separate effects of background and illumination on lightness

Psihologija ◽  
2007 ◽  
Vol 40 (4) ◽  
pp. 543-565
Author(s):  
Suncica Zdravkovic
Keyword(s):  
Illumination Level ◽  
Background Color ◽  
The Third ◽  
Lightness Contrast ◽  
3D Representation

Four experiments attempted to establish an effect of context on lightness. Lightness is one of the dimensions of color and it varies from black to white. Most of our stimuli were inspired by simultaneous lightness contrast illusion. First two experiments contrast the size of an effect produced by the change of background color vs. the change in illumination. The third experiment deals with different type of illusions, where the effect is obtained through the appearance of multiple illumination levels. The last experiment takes into account the ratio of the target and the background. The results reveal the size of effects produced separately by the background color and illumination level and suggest the prime importance of background. Also there are other factors such as reflectance range in the scene, incremental and decremental targets, and 2D vs. 3D representation.

scholarly journals Morphological, anatomical, physiological and biochemical adaptations of Pittosporum tobira (Thunb.) W.T.Aiton and P. heterophyllum Franch. to the illumination level

2019 ◽  
Keyword(s):  
Photosynthetic Apparatus ◽  
Illumination Level ◽  
Low Light ◽  
Interspecific Differences ◽  
Common Trend ◽  
Sensitive Organ ◽  
Anatomical Adaptations ◽  
Intense Solar Radiation ◽  
Diagnostic Indicator ◽  
Physiological And Biochemical

Anatomical, morphological, physiological and biochemical adaptations of leaf as the most ecologically sensitive organ in the species P. tobira and P. heterophyllum, grown in the zones of greenhouse complex with different degree of illumination (1 zone – the level of illumination is 100–300 lx, zone 2 – 3000–7000 lx, and zone 3 – more than 10 thousand lx).) were studied. We revealed the structural morphological and anatomical adaptations, which manifested in the increase of leaf structure xeromorphy (thickening of the leaf, adaxial epidermis and columnar parenchyma, increasing pubescence density) under conditions of high insolation. With a low level of illumination in plants of both species, the thickness of the lamina decreased, mainly due to the mesophyll – the number of layers of the columnar parenchyma and the size of the cells reduced. Interspecific differences in the content of photosynthetic pigments in both species studied were found. A common trend in plants under low light conditions was decrease of chlorophyll a compared with the control, whereas the concentration of chlorophyll b in the leaves of plants increased with shading and high insolation. The result of the adaptation of the photosynthetic apparatus of Pittosporum plants, which normalizes its functioning, is a decreasing chlorophyll index both during shading and intense solar radiation. The maximum is determined in the range of 3–7 thousand lx. Such light regime is optimal for plants of the species studied. The observed decreasing pigment index in P. heterophyllum leaves is considered as an adaptive response of more light-loving species of the genus to their cultivation in the shade. The dependence of the peroxidase activity in Pittosporum leaves on the illumination level was studied. Adaptive reactions manifested in changes of peroxidase fractional composition in the leaves of the plants grown in different conditions. The obtained results on the activation and inactivation of the enzymatic activity of free and cell wall-associated peroxidase are interesting for using as an additional diagnostic indicator of stress degree for the plants of the interiors. It was established that adaptive changes in experimental plants were determined by the origin of species and their ecological and biological features.

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