Brightness Matching, Brightness Cancellation, and Increment Threshold in the Ehrenstein Illusion

Perception ◽  
1984 ◽  
Vol 13 (5) ◽  
pp. 513-520 ◽  
Author(s):  
Lothar Spillmann ◽  
Kenneth Fuld ◽  
Christa Neumeyer
Keyword(s):  
Detection Threshold ◽  
Receptive Fields ◽  
Negative Contrast ◽  
Positive Contrast ◽  
Relative Strength ◽  
Lateral Interaction ◽  
Test Flash ◽  
Increment Threshold ◽  
Small Test ◽  
Luminance Increment

Matching and cancellation techniques were used to measure the relative strength of the Ehrenstein illusion in dark figures on a light background (negative contrast) and light figures on a dark background (positive contrast). Brightness enhancement on the former was shown to be maximally 0.28 log unit (relative to the detection threshold), and darkness enhancement on the latter 0.43 log unit. Values differed little with figure–ground contrast (down to a minimum of ±0.5), but decreased with decreasing level of illumination. The luminance increment (decrement) needed to match the illusory brightness (darkness) was similar in size to the luminance decrement (increment) needed to cancel the illusion. The increment threshold for a small test flash measured in three locations relative to the subjective contour delineating the illusion did not differ systematically. The results are compatible with a neurophysiological explanation of the Ehrenstein illusion in terms of line-induced lateral interaction in hypercomplex receptive fields.

scholarly journals Positive Contrast Imaging of SPIO Nanoparticles

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Chenghong Lin ◽  
Shuhui Cai ◽  
Jianghua Feng
Keyword(s):  
Negative Contrast ◽  
Superparamagnetic Iron Oxide ◽  
Positive Contrast ◽  
Disease Diagnosis ◽  
Cell Labeling ◽  
Contrast Imaging ◽  
Advantages And Disadvantages ◽  
Tissue Interface ◽  
Dark Signal ◽  
Ideal Method

It is advantageous to achieve positive contrast images instead of negative contrast images in superparamagnetic iron-oxide (SPIO) nanoparticles-based MR imaging in order to distinguish the signal surrounding SPIO nanoparticles from the dark signal due to local field inhomogeneity and the artifacts due to tissue interface and background noise, eliminate the inherent defects in the traditional MRI such as partial-volume effects and large void volume for reliable visualization, and increase contrast-to-noise ratio. Many methods generating positive signal with SPIO nanoparticles have been developed in the last decade. This paper provides an overview of current visualization methods and states their advantages and disadvantages. In practice, these techniques have been widely applied to cell labeling and disease diagnosis and monitoring. However, there is still a need for an ideal method to achieve both accuracy and sensitivity.

Enhancing the Mobile User Experience Through Colored Contrasts

2019 ◽  
pp. 863-876
Author(s):  
Jean-Éric Pelet ◽  
Basma Taieb
Keyword(s):  
Behavioral Intentions ◽  
Negative Contrast ◽  
Positive Contrast ◽  
Mobile User ◽  
Structural Equations ◽  
Color Contrast ◽  
Affective States ◽  
Positive Effects ◽  
Green Background ◽  
Managerial Implications

This chapter examines the effects of the mobile-phone website colored contrasts and the affective states of the consumer (emotions and moods) and trust, respectively, on intention to revisit, buy on, and recommend the mobile website. For this purpose, a factorial plan 2x2 was developed, and a mobile website, with two different alternatives, was designed especially for the experiment: positive contrast (yellow text on green background) and negative contrast (green text on yellow background). The research was conducted on French consumers. Three-hundred twelve valid responses were collected through online and personal survey questionnaires. Data was analysed using the method of structural equations. The results show the significant effects of mobile website's color contrast on behavioral intentions. Perceived dominance and trust towards the website have positive effects on behavioral intentions, whereas mood has non-significant effects on behavioral intentions. Managerial implications are discussed.

Enhancing the Mobile User Experience Through Colored Contrasts

2018 ◽  
pp. 6070-6082
Author(s):  
Jean-Éric Pelet ◽  
Basma Taieb
Keyword(s):  
Behavioral Intentions ◽  
Negative Contrast ◽  
Positive Contrast ◽  
Mobile User ◽  
Structural Equations ◽  
Color Contrast ◽  
Affective States ◽  
Positive Effects ◽  
Green Background ◽  
Managerial Implications

This study examines the effects of the mobile-phone website colored contrasts and the affective states of the consumer (emotions and moods) and trust respectively on intention to revisit, buy on and recommend the mobile website. For this purpose, a factorial plan 2x2 was developed and a mobile website, with two different alternatives, was designed especially for the experiment: positive contrast (yellow text on green background) and negative contrast (green text on yellow background). The research was conducted on French consumers. 312 valid responses were collected through online and personal survey questionnaires. Data was analysed using the method of structural equations. The results show the significant effects of mobile website's color contrast on behavioral intentions. Perceived dominance and trust towards the website have positive effects on behavioral intentions, whereas mood has non-significant effects on behavioral intentions. Managerial implications are discussed.

scholarly journals Non-informative vision improves spatial tactile discrimination on the shoulder but does not influence detection sensitivity

2020 ◽  
Vol 238 (12) ◽  
pp. 2865-2875
Author(s):  
Fabrizio Leo ◽  
Sara Nataletti ◽  
Luca Brayda
Keyword(s):  
Tactile Stimulation ◽  
Detection Threshold ◽  
Receptive Fields ◽  
Judgment Task ◽  
The Body ◽  
Detection Sensitivity ◽  
Body Parts ◽  
Tactile Acuity ◽  
Tactile Stimuli ◽  
Numerosity Judgment

Abstract Vision of the body has been reported to improve tactile acuity even when vision is not informative about the actual tactile stimulation. However, it is currently unclear whether this effect is limited to body parts such as hand, forearm or foot that can be normally viewed, or it also generalizes to body locations, such as the shoulder, that are rarely before our own eyes. In this study, subjects consecutively performed a detection threshold task and a numerosity judgment task of tactile stimuli on the shoulder. Meanwhile, they watched either a real-time video showing their shoulder or simply a fixation cross as control condition. We show that non-informative vision improves tactile numerosity judgment which might involve tactile acuity, but not tactile sensitivity. Furthermore, the improvement in tactile accuracy modulated by vision seems to be due to an enhanced ability in discriminating the number of adjacent active electrodes. These results are consistent with the view that bimodal visuotactile neurons sharp tactile receptive fields in an early somatosensory map, probably via top-down modulation of lateral inhibition.

The Influence of Olfactory Contexts on the Sequential Rating of Odor Pleasantness

Perception ◽  
2016 ◽  
Vol 46 (3-4) ◽  
pp. 393-405 ◽  
Author(s):  
Shiori Nakano ◽  
Saho Ayabe-Kanamura
Keyword(s):  
Negative Contrast ◽  
Positive Contrast ◽  
Stimulus Context ◽  
Sensory Stimuli ◽  
Current Stimulus ◽  
Hedonic Contrast ◽  
Positive Stimuli ◽  
A Current

When we sequentially evaluate the characteristics of sensory stimuli, our evaluation of a current stimulus is influenced by those preceding it. One such effect is called hedonic contrast, whereby stimuli are rated more negatively (negative contrast) or positively (positive contrast) if they are preceded by more or less pleasant stimuli. The present study investigated the characteristics of hedonic contrast for olfaction and compared these characteristics with those of a more oft-studied modality, vision. The results from two experiments indicated that both positive and negative contrasts occurred in the sequential rating of picture pleasantness, whereas only negative contrast occurred for olfactory ratings. Notably, overrating of hedonically negative odors following a positive olfactory context was observed even when participants had already rated these same negative odors beforehand; conversely, this did not occur for positive contrast for either sense. These findings indicate that negative odors are more strongly influenced than positive ones, and the rating of positive stimuli may be adjusted to the preceding rating independent of stimulus context. The findings of this study revealed the unique characteristics of hedonic contrast for the olfactory senses.

Topographic Receptive Fields and Patterned Lateral Interaction in a Self-Organizing Model of the Primary Visual Cortex

1997 ◽  
Vol 9 (3) ◽  
pp. 577-594 ◽  
Author(s):  
Joseph Sirosh ◽  
Risto Miikkulainen
Keyword(s):  
Neural Network ◽  
Ocular Dominance ◽  
Receptive Fields ◽  
Afferent Input ◽  
Lateral Interaction ◽  
Lateral Interactions ◽  
Cooperative Development ◽  
Correlated Activity ◽  
Lateral Connection ◽  
Self Organizing

This article presents a self-organizing neural network model for the simultaneous and cooperative development of topographic receptive fields and lateral interactions in cortical maps. Both afferent and lateral connections adapt by the same Hebbian mechanism in a purely local and unsupervised learning process. Afferent input weights of each neuron self organize into hill-shaped profiles, receptive fields organize topographically across the network, and unique lateral interaction profiles develop for each neuron. The model demonstrates how patterned lateral connections develop based on correlated activity and explains why lateral connection patterns closely follow receptive field properties such as ocular dominance.

Dynamic Contrast Perception Assessed by Pattern Masking

Perception ◽  
1996 ◽  
Vol 25 (1_suppl) ◽  
pp. 19-19
Author(s):  
R W Bowen ◽  
H de Ridder
Keyword(s):  
Spatial Frequency ◽  
Contrast Enhancement ◽  
Time Course ◽  
Negative Contrast ◽  
Positive Contrast ◽  
Opposite Polarity ◽  
Enhancement Effect ◽  
Mask Duration ◽  
Pattern Masking ◽  
Contrast Perception

The perceived contrast of a pulsed grating of about 100 ms duration can exceed that of shorter or longer exposures. We investigated this contrast enhancement effect with pattern masking. The pulsed mask patterns were extended cosines (5 deg square, 35 cd m−2 mean luminance, 0.3 contrast) of 50 to 500 ms duration. Mask spatial frequency was 1 or 6 cycles deg−1. The test patterns (of equivalent spatial frequency) were sixth derivative Gaussians, either positive (ON pathway mediation) or negative (OFF pathway mediation) and of 30 ms duration. The test pattern could be centred on a light bar of the cosine (positive contrast) or a dark bar (negative contrast). Test and mask had simultaneous onset. For a 1 cycle deg−1 test and mask of the same polarity, the test threshold/mask duration function is nonmonotonic (peak at 83 – 100 ms). The function was similar for either positive or negative stimuli. Thus, we measured an analogue to the contrast enhancement effect, and found enhancement for negative as well as positive contrast components. For same-polarity 6 cycles deg−1 test and mask, threshold increased monotonically to 500 ms (no enhancement). For both 1 and 6 cycles deg−1 stimuli of opposite polarity, the threshold/mask duration function is sharply elevated and constant for masks of 83 ms or more. The same-polarity masking functions imply activation of either transient (1 cycle deg−1 stimuli) or sustained (6 cycles deg−1 stimuli) ON or OFF pathways. The opposite-polarity functions suggest that the time course of ON — OFF pathway interaction is similar for sustained and transient pathways.

Designing Website Interfaces for M-Commerce With Consideration for Adult Consumers

2017 ◽  
pp. 288-308
Author(s):  
Jean-Éric Pelet ◽  
Basma Taieb
Keyword(s):  
Negative Contrast ◽  
Positive Contrast ◽  
Interaction Effects ◽  
Future Research ◽  
Color Contrast ◽  
Website Design ◽  
Design Elements ◽  
Dark Background ◽  
Revisit Intentions ◽  
Principal Design

This chapter analyzes the interaction effects between the principal design cues of a mobile commerce website, such as background/foreground colors, font text and layout. Three experiments have been conducted based on visits to a fictitious m-commerce website. Experiment 1 manipulates the levels of color contrast: positive contrast (light text on a dark background) versus negative contrast (dark text on a light background). In experiment 2, contrast and font have been manipulated with a complete factorial plan: 2 x 2 (negative vs positive contrast x serif font vs sans serif font). Finally, contrast and layout have been manipulated in a third experimental 2 x 2 plan (negative vs positive contrast x dense vs airy layout). This research involved 219 French participants. Results show significant effects of the positive contrast (light text on a dark background) of the mobile website design on the purchase and revisit intentions of adults. Discussions about the interaction effects of design elements, limitations and directions for future research follow.

scholarly journals Live nephron imaging by MRI

2014 ◽  
Vol 307 (10) ◽  
pp. F1162-F1168 ◽  
Author(s):  
Chunqi Qian ◽  
Xin Yu ◽  
Nikorn Pothayee ◽  
Stephen Dodd ◽  
Nadia Bouraoud ◽  
...  
Keyword(s):  
Simultaneous Detection ◽  
Negative Contrast ◽  
Positive Contrast ◽  
Gadopentetate Dimeglumine ◽  
Live Imaging ◽  
Renal Tubules ◽  
Local Sensitivity ◽  
Local Detectors ◽  
Integrated Detector

The local sensitivity of MRI can be improved with small MR detectors placed close to regions of interest. However, to maintain such sensitivity advantage, local detectors normally need to communicate with the external amplifier through cable connections, which prevent the use of local detectors as implantable devices. Recently, an integrated wireless amplifier was developed that can efficiently amplify and broadcast locally detected signals, so that the local sensitivity was enhanced without the need for cable connections. This integrated detector enabled the live imaging of individual glomeruli using negative contrast introduced by cationized ferritin, and the live imaging of renal tubules using positive contrast introduced by gadopentetate dimeglumine. Here, we utilized the high blood flow to image individual glomeruli as hyperintense regions without any contrast agent. These hyperintense regions were identified for pixels with signal intensities higher than the local average. Addition of Mn2+ allowed the simultaneous detection of both glomeruli and renal tubules: Mn2+ was primarily reabsorbed by renal tubules, which would be distinguished from glomeruli due to higher enhancement in T1-weighted MRI. Dynamic studies of Mn2+ absorption confirmed the differential absorption affinity of glomeruli and renal tubules, potentially enabling the in vivo observation of nephron function.

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