Contrast Perception Research Articles

The development of perception of English tense-lax vowel contrast by monolingual English-speaking and bilingual Mandarin-English children

The development of perception of English tense-lax vowel contrast by monolingual English-speaking and bilingual Mandarin-English children

Swimming behaviour tunes fish polarization vision to double prey sighting distance

The analysis of the polarization of light expands vision beyond the realm of colour and intensity and is used for multiple ecological purposes among invertebrates including orientation, object recognition, and communication. How vertebrates use polarization vision as part of natural behaviours is widely unknown. In this study, I tested the hypothesis that polarization vision improves the detection of zooplankton prey by the northern anchovy, Engraulis mordax, the only vertebrate with a demonstrated photoreceptor basis explaining its polarization sensitivity. Juvenile anchovies were recorded free foraging on zooplankton under downwelling light fields of varying percent polarization (98%, 67%, 19%, and 0% - unpolarized light). Analyses of prey attack sequences showed that anchovies swam in the horizontal plane perpendicular, on average, to the polarization direction of downwelling light and attacked prey at pitch angles that maximized polarization contrast perception of prey by the ventro-temporal retina, the area devoted to polarization vision in this animal. Consequently, the mean prey location distance under polarized light was up to 2.1 times that under unpolarized conditions. All indicators of polarization vision mediated foraging were present under 19% polarization, which is within the polarization range commonly found in nature during daylight hours. These results demonstrate: (i) the first use of oriented swimming for enhancing polarization contrast detection of prey, (ii) its relevance to improved foraging under available light cues in nature, and (iii) an increase in target detection distance that is only matched by polarization based artificial systems.

Effect of brightness on speckle contrast and human speckle perception in laser projection systems

Speckle noise is a serious problem for laser projectors because it deteriorates the image quality. The brightness of the image is one of the important parameters to determining the speckle perception. In this paper, the effect of brightness on speckle contrast is investigated using matte and silver screens for cinema. The brightness was changed by using ND filters or changing the on-and-off duty cycle of a DMD device in a digital cinema projector. It is shown that the brightness does not affect the speckle contrast measured by a CCD camera. Then, the effect of the brightness on human speckle perception is investigated. It is shown that the brightness of the image significantly affects human speckle perception. Speckle patterns created by the image with higher brightness are more noticeable than those with lower brightness when the speckle contrast measured by a camera is the same.

Stock collapse or stock recovery? Contrasting perceptions of a depleted cod stock

Abstract ICES assessments of cod (Gadus morhua) in the west of Scotland (ICES Division 6a) suggest the biomass has collapsed and that fishing mortality rate (F) has remained high. In contrast, other stocks in the same fishery, and adjacent cod stocks all show marked declines in fishing mortality and some recovery of the biomass. The perception of the status of 6a cod appears to be dependent on the assumption that the fishery exploitation pattern is flat topped. An assessment that allows the exploitation to take a domed shape produces results that suggest a marked decline in fishing mortality rate and that the spawning stock biomass has recovered to the minimum biomass reference point, Blim. The reduction in F is consistent with substantial reductions in fishing effort and shows a similar pattern to stocks taken within the same fishery. The management implications arising from the two assessments differ substantially. The analysis indicates that benchmark assessments need to test assessment model conditioning assumptions more widely and that management advice needs to consider a more comprehensive range of information about the stock and fishery.

Impacts of authenticity, degree of adaptation and cultural contrast on travellers’ memorable gastronomy experiences

ABSTRACTGastronomy is an essential component of the travel experience and isbecoming one of the “best things to do” in many destinations.Impressions gained from local food coupled with tourists’ attitudes can influence the living experience. This paper analyses the extent to whichthe perceived authenticity of local food, the degree of adaptation andcultural contrast determine memorable tourist experiences. Moreover, itproposes the moderating effect of searching for authenticity andadaptation ability. Results from a sample of international tourists whotried a typical dish support the positive effect of authenticity and culturalcontrast on the perceived experience, whereas product adaptationreduces the perception of authenticity and cultural contrast. Authenticityhas a greater effect on experience perception when actively sought bytourists, and individuals are less influenced by cultural contrast whenthey are unable to adapt to different cultures.

Comparison of two devices to simulate vision with intraocular lenses.

IntroductionThe simulation of vision with intraocular lenses (IOLs) prior to the clinical validation is of great interest for manufacturers as well as clinicians. We have tested the influence of different IOLs on the perception of contrast using different devices.Materials and methodsA Rassow telescope and the VirtIOL have been used to assess the contrast sensitivity function (CSF) through monfocal IOL (CT Asphina 409 MP, IOL 1), multifocal IOL (AT LISA tri 839 MP, IOL 2) and extended-depth-of-focus-IOL (TECNIS Symfony ZXR00, IOL3) in 21 participants, aged between 22 and 29 years. Contrast sensitivity (CS) was tested at various spatial frequencies (3–30 cycles per degree), using the Tuebingen contrast sensitivity test.ResultsAll tested IOL reduced the CS when compared to measurements with a trial lens correction of refractive errors. The analysis of the area under the curve of the contrast sensitivity function (AUC-CSF) revealed a significant reduction compared to the trial lens correction in case the Rassow telescope was used (IOL 1: P=0.008; IOL2: P<0.001; IOL3: P<0.001) and the same was true for the VirtIOL device for IOL2 and IOL3 (IOL2: P<0.001; IOL3: P<0.001), but not for IOL1 (P=0.192). Interdevice analysis of the AUC-CSF revealed significant differences for IOL1 and IOL2 (IOL1: P=0.025; IOL2: P<0.001), while no difference was found for IOL3 (P=0.092). Bland–Altman analysis as well as intraclass correlations coefficients indicated only weak interdevice agreement for the tested IOL.ConclusionThe assessment of the interdevice analysis for the Rassow telescope and the VirtIOL device revealed only a minor agreement between the two devices. In order to investigate vision with IOLs prior to a clinical validation, the use of the VirtIOL device is recommended.

How the tracking of habitual rate influences speech perception.

Listeners are known to track statistical regularities in speech. Yet, which temporal cues are encoded is unclear. This study tested effects of talker-specific habitual speech rate and talker-independent average speech rate (heard over a longer period of time) on the perception of the temporal Dutch vowel contrast /ɑ/-/a:/. First, Experiment 1 replicated that slow local (surrounding) speech contexts induce fewer long /a:/ responses than faster contexts. Experiment 2 tested effects of long-term habitual speech rate. A high-rate group listened to ambiguous vowels embedded in "neutral" speech from Talker A, intermixed with fast speech from Talker B. A low-rate group listened to the same neutral speech from Talker A, and/but to Talker B speaking at a slow rate. Between-groups comparison of the neutral trials showed that the high-rate group demonstrated a lower proportion of /a:/ responses, indicating that Talker A's habitual speech rate sounded slower when B was faster. In Experiment 3, both talkers produced speech at both rates, removing the different habitual speech rates of Talkers A and B, while maintaining the average rates differing between groups. In Experiment 3, no global rate effect was observed. Taken together, the present experiments show that a talker's habitual rate is encoded relative to the habitual rate of another talker, carrying implications for episodic and constraint-based models of speech perception. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Different Inhibitory Interneuron Cell Classes Make Distinct Contributions to Visual Contrast Perception.

While recent work has revealed how different inhibitory interneurons influence responses of cortical neurons to sensory stimuli, little is known about their distinct contributions to sensory perception. Here, we optogenetically activated different genetically defined interneurons [parvalbumin (PV), somatostatin (SST), vasoactive intestinal peptide (VIP)] in visual cortex (V1) of mice working at threshold in a contrast increment detection task. The visual stimulus was paired with optogenetic stimulation to assess how enhancing V1 inhibitory neuron activity during visual processing altered task performance. PV or SST activation impaired, while VIP stimulation improved, contrast increment detection. The impairment produced by PV or SST activation persisted over several weeks of testing. In contrast, mice learned to reliably detect VIP activation in the absence of any natural visual stimulus. Thus, different inhibitory signals make distinct contributions to visual contrast perception.

Contrasting perceptions of male and female dental students regarding smile aesthetics based on their gingival display

Background: Perception consists of personal opinion in relation to an object. In terms of aesthetics, perception normally differs from one individual to another based on several factors such as gender. When expressing emotion, a smile is the most important facial expression whose aesthetics are constructed from a number of components, including gingival display. Purpose: This study aimed to establish the comparative perceptions of the smile aesthetics of male and female dental students based on their gingival display. Methods: 36 dental students, divided equally according to gender, were enrolled in this study. Photographic images of the smile of each subject were taken from a frontal direction with a Canon EOS 700D digital camera and subsequently printed. Assessments were conducted by comparing the photographs of subjects from the perspective of smile references based on the gingival display, followed by subject scoring on the basis of smile classification. Assessments were conducted twice within a two-week period to confirm test reliability. The data collected was analyzed by means of kappa statistic and U-Mann Whitney tests. Results: The test results indicated that all subjects demonstrated a coincidence in their analysis (κ=0.84). Statistical analysis showed that a score of 0.902 (p&gt;0.05) had been produced by a U-Mann Whitney test. Conclusion: It can be concluded that no difference exists between male and female students in the perception of smile aesthetics based on the gingival display.

Las competencias del futuro profesional de enfermería desde la perspectiva del profesorado y el alumnado: Un estudio de caso

Resumen:En este artículo se analizan y contrastan las percepciones y valoraciones de estudiantes y profesorado sobre el desarrollo competencial de los futuros profesionales de Enfermería de una universidad privada de Puerto Rico. Se trata de una investigación descriptiva por encuesta en la que han participado 138 sujetos. Los resultados evidencian, entre otras cuestiones, que el alumnado tiende a mostrarse más satisfecho con los logros alcanzados que los docentes, aunque ambos coinciden en señalar que existen brechas importantes entre la formación adquirida por los futuros profesionales de Enfermería y aquella otra que sería deseable haber alcanzado para un buen desempeño profesional. Las competencias más adquiridas y mejor valoradas por ambos colectivos están vinculadas a los principios y valores éticos de la profesión, mientras que los niveles de logro más bajos están relacionados con el diseño y evaluación de sistemas de cuidado de la salud, el uso de los recursos de salud de la comunidad y la participación en organizaciones profesionales.

Assessment of contrast perception of obstacles in a tunnel entrance.

Background: The purpose of this study was to assess the contrast perception of obstacles in a tunnel entrance which was placed in Ilam Province, Iran.Methods: An obstacle with the reflection coefficient of 20% was mounted at the entrance of thetunnel and then, the car was placed near the tunnel entrance and the intrinsic luminance of the road (Lr,intrinsic) and obstacle (Lo,intrinsic) were measured inside the car using the luminance meter.Results: Intrinsic luminance of obstacle and road at the entrance of the tunnel were measured as 41 and 17 cd/m2, respectively. The contrast perception of obstacle in deriver’s eyes and in the safe stopping distance (SSD) from the tunnel entrance was determined as 2.79 cd/m2. At the entrance of the studied tunnel, the contrast perception of obstacles with the reflection coefficient of 20% was lower than the minimum contrast perception (28%) recommended by International Commission on Illumination.Conclusion: The main conclusion that can be drawn from it, is that this obstacle in the SSD from the tunnel entrance cannot be conceived by the drivers, which may lead to higher rate of road traffic crashes.

El concepto de la intuición categorial en Husserl

Dieter Lohmar: Husserls concept of categorial intuition Husserl’s theory of categorial intuition is presented in the 6.th Logical Investigation. It starts with the question: what fulfills the specific categorial elements of thinking and language? Husserl’s analysis of the structure of categorial intuition opens up with a confrontation of simple acts of perception in contrast with complex, founded acts of categorial intuition. This is illustrated by the difference between simple synthesis of identification in continuous perception in contrast to the thematic identification of the same object. Then the crucial “fulfilling” function of the “synthesis of coincidence” between implicite and explicite (partial-)intentions in categorial intuition is very carefuly presented. The source, the special character and the special mode of givenness of the synthesis of coincidence is characterized: They are non-sensual contents which are nevertheless given to us in the transition of the perceptual acts within the whole structure of a categorial act. This leds to a detailled categorial act. In the end there is to be found a critical evaluation of the procedure of seeing essenses (Wesensschau) viewed as a special case of categorial intuition. The performance and the limits of this central phenomenological method are discussed.

Light Microscopy Study of the Retina of the Yellow-Legged Gull, Larus Michahellis, and the Relationship between Environment and Behaviour

The morphology of the retina of the adult Yellow-legged Gull, Larus michahellis, was examined in transverse sections under light microscopy in order to study the retinal adaptations to their specific photic environment that determines their behaviour. We identified rods, single cones and unequal double cones. Although it is a duplex retina, cones are preponderant and coloured oil droplets are present in their inner segments. As several colours in oil droplets are observed, it seems reasonable to conclude that several types of cones are present. Moreover, more cones per unit area are found in the central regions of the retina than in peripheral regions. A probable area centralis is observed. In the inner nuclear layer, two types of horizontal cells, and bipolar and amacrine cells can be recognised. Also, ganglion cells, characterised by prominent nuclei and nucleoli, vary in size and abundance among different regions in the retina. Comparisons are made with the retinae of other marine birds. The morphological characteristics of this retina indicate that Larus michahellis possesses: a good ability to discriminate colour; complex visual processing in the inner retina in order to mediate contrast and motion perception; and an elevated acuity in areas of high ganglion cell density.

Oretinex-DI: Pre-Processing Algorithms for Melanoma Image Enhancement

In Medical imaging, the dermoscopic images analysis is quite useful for the skin cancer detection. The automatic computer assisted diagnostic systems (CADS) require dermoscopic image enhancement for human perception and analysis. The traditional image enhancements methods lack the synchronization among contrast perception between human and the digital images. This paper proposes an optimized-Retinex (ORetinex) image enhancement algorithm to remove light effects, which is quite suitable for the dermoscopic image for clinical analysis for Melanoma. The value of global contrast factor (GCF) and contrast per pixel (CPP) is computed and compared with the traditional methods of image enhancements including contrast enhancement, CLAHE,Adaptive histogram equalization, Bilinear filtering and the proportion of GCF and CPP is found quite optimal as compare to these traditional methods.

The Influence of Physical Illumination on Lightness Perception in Simultaneous Contrast Displays.

Three experiments investigated the role of physical illumination on lightness perception in simultaneous lightness contrast (SLC). Four configurations were employed: the classic textbook version of the illusion and three configurations that produced either enhanced or reduced SLC. Experiment 1 tested the effect of ambient illumination on lightness perception. It simulated very dark environmental conditions that nevertheless still allowed perception of different shades of gray. Experiment 2 tested the effect of the intensity of Gelb lighting on lightness perception. Experiment 3 presented two conditions that integrated illumination conditions from Experiments 1 and 2. Our results demonstrated an illumination effect on both lightness matching and perceived SLC contrast: As the intensity of illumination increased, the target on the black background appeared lighter, while the target on the white background was little affected. We hypothesize the existence of two illumination ranges that affect lightness perception differently: low and normal. In the low range, the SLC contrast was reduced and targets appeared darker. In the normal range, the SLC contrast and lightness matchings for each background were little changed across illumination intensities.

Is the straddle effect in contrast perception limited to second-order spatial vision?

Previous work on the straddle effect in contrast perception (Foley, 2011; Graham & Wolfson, 2007; Wolfson & Graham, 2007, 2009) has used visual patterns and observer tasks of the type known as spatially second-order. After adaptation of about 1 s to a grid of Gabor patches all at one contrast, a second-order test pattern composed of two different test contrasts can be easy or difficult to perceive correctly. When the two test contrasts are both a bit less (or both a bit greater) than the adapt contrast, observers perform very well. However, when the two test contrasts straddle the adapt contrast (i.e., one of the test contrasts is greater than the adapt contrast and the other is less), performance drops dramatically. To explain this drop in performance—the straddle effect—we have suggested a contrast-comparison process. We began to wonder: Are second-order patterns necessary for the straddle effect? Here we show that the answer is “no”. We demonstrate the straddle effect using spatially first-order visual patterns and several different observer tasks. We also see the effect of contrast normalization using first-order visual patterns here, analogous to our prior findings with second-order visual patterns. We did find one difference between first- and second-order tasks: Performance in the first-order tasks was slightly lower. This slightly lower performance may be due to slightly greater memory load. For many visual scenes, the important quantity in human contrast processing may not be monotonic with physical contrast but may be something more like the unsigned difference between current contrast and recent average contrast.

Contrasting practices and perceptions of urban agriculture in Portugal

ABSTRACTThis paper presents a conceptual exploration of Urban Agriculture in Portugal. We argue that Portuguese Urban Agriculture primarily focuses on food production for self-consumption and that its links with the other components of urban as a system are quite limited.To substantiate our argument several Urban Agriculture international definitions are presented and critically analysed along with: 1) interviews of relevant key actors; and, 2) a web search based on key words. We conclude that there is a need to clarify the very concept of Urban Agriculture among actors involved. This could be achieved through a national network able to raise a must needed debate about this promising sector. Political decision makers, civil society, and planners, among others should be involved in this collaborative process. Finally, the paper brings some reflections on what the Portuguese experience contributes to the broader debate and definitions of Urban Agriculture.

Contrasting human perceptions of and attitudes towards two threatened small carnivores, Lycalopex fulvipes and Leopardus guigna, in rural communities adjacent to protected areas in Chile

The interaction between humans and small carnivores is a phenomenon especially frequent in rural fringes, as is the case of communities surrounding natural areas. In Chile, two species of threatened carnivores, the Darwin’s Fox and the Guigna, have increased their contact with humans due to human-induced changes in their habitat. The objective of this study was to characterize the interactions of these species with humans by assessing human perceptions and attitudes toward them, and to assess livestock and poultry ownership and management practices in local communities to evaluate their possible roles in the phenomenon. We conducted semi-structured interviews in rural communities adjacent to natural protected areas of two different regions in southern Chile. We found that people have a more positive perception of Darwin’s Foxes than Guignas, but both species are considered damaging due to poultry attacks. Livestock and poultry management was generally deficient. Improvements in animal management and education programs could lead to a significant decrease in negative interactions.

Identifying /l/ and /n/ in English by multi-dialectal speakers of Mandarin

Native speakers of Standard Mandarin are mostly proficient in their local dialects which were acquired at home before or parallel to the Standard Mandarin. The Mandarin dialects that share general grammar mainly differ in their phonological features. A well-known example is the contrast of /l/ and /n/, which is not fully maintained or completely absent in many southern Mandarin dialects. This study investigated how perception of the English consonantal contrast may be influenced by experience in Mandarin dialects with varying phonemic status and distribution of the sounds. We examined the identification of the two consonants in various phonetic environments by Chinese bi-dialectal speakers who were all advanced learners of English-as-a-foreign-language. Results confirmed predicted perceptual difficulties across dialect groups as well as revealed other phonetic factors affecting the perceptual accuracy.

Generalization of Classic Question Order Effects Across Cultures

Questionnaire design is routinely guided by classic experiments on question form, wording, and context conducted decades ago. This article explores whether two question order effects (one due to the norm of evenhandedness and the other due to subtraction or perceptual contrast) appear in surveys of probability samples in the United States and 11 other countries (Canada, Denmark, Germany, Iceland, Japan, the Netherlands, Norway, Portugal, Sweden, Taiwan, and the United Kingdom; N = 25,640). Advancing theory of question order effects, we propose necessary conditions for each effect to occur, and found that the effects occurred in the nations where these necessary conditions were met. Surprisingly, the abortion question order effect even appeared in some countries in which the necessary condition was not met, suggesting that the question order effect there (and perhaps elsewhere) was not due to subtraction or perceptual contrast. The question order effects were not moderated by education. The strength of the effect due to the norm of evenhandedness was correlated with various cultural characteristics of the nations. Strong support was observed for the form-resistant correlation hypothesis.