scholarly journals Dissociable effects of visual crowding on the perception of color and motion

2020 ◽  
Vol 117 (14) ◽  
pp. 8196-8202 ◽  
Author(s):  
John A. Greenwood ◽  
Michael J. Parsons
Keyword(s):  
Deleterious Effect ◽  
Peripheral Vision ◽  
The Other ◽  
Correct Recognition ◽  
Visual Features ◽  
Double Dissociation ◽  
Multiple Processes ◽  
Specific Manner ◽  
Visual Crowding ◽  
Selective Mechanism

Our ability to recognize objects in peripheral vision is fundamentally limited by crowding, the deleterious effect of clutter that disrupts the recognition of features ranging from orientation and color to motion and depth. Previous research is equivocal on whether this reflects a singular process that disrupts all features simultaneously or multiple processes that affect each independently. We examined crowding for motion and color, two features that allow a strong test of feature independence. “Cowhide” stimuli were presented 15° in peripheral vision, either in isolation or surrounded by flankers to give crowding. Observers reported either the target direction (clockwise/counterclockwise from upward) or its hue (blue/purple). We first established that both features show systematic crowded errors (biased predominantly toward the flanker identities) and selectivity for target–flanker similarity (with reduced crowding for dissimilar target/flanker elements). The multiplicity of crowding was then tested with observers identifying both features. Here, a singular object-selective mechanism predicts that when crowding is weak for one feature and strong for the other that crowding should be all-or-none for both. In contrast, when crowding was weak for color and strong for motion, errors were reduced for color but remained for motion, and vice versa with weak motion and strong color crowding. This double dissociation reveals that crowding disrupts certain combinations of visual features in a feature-specific manner, ruling out a singular object-selective mechanism. Thus, the ability to recognize one aspect of a cluttered scene, like color, offers no guarantees for the correct recognition of other aspects, like motion.

scholarly journals Dissociable effects of visual crowding on the perception of colour and motion

2019 ◽  
Author(s):  
John A. Greenwood ◽  
Michael J. Parsons
Keyword(s):  
Peripheral Vision ◽  
Population Coding ◽  
Visual Features ◽  
Double Dissociation ◽  
Multiple Processes ◽  
Underlying Mechanisms ◽  
High Level ◽  
Object Features ◽  
Visual Crowding ◽  
Selective Mechanism

AbstractOur ability to recognise objects in peripheral vision is fundamentally limited by crowding, the deleterious effect of clutter that disrupts the recognition of features ranging from orientation and colour to motion and depth. Prior research is equivocal on whether this reflects a singular process that disrupts all features simultaneously or multiple processes that affect each independently. We examined crowding for motion and colour, two features that allow a strong test of feature independence. ‘Cowhide’ stimuli were presented 15 degrees in peripheral vision, either in isolation or surrounded by flankers to give crowding. Observers reported either the target direction (clockwise/counterclockwise from upwards) or its hue (blue/purple). We first established that both features show systematic crowded errors (predominantly biased towards the flanker identities) and selectivity for target-flanker similarity (with reduced crowding for dissimilar target/flanker elements). The multiplicity of crowding was then tested with observers identifying both features: a singular object-selective mechanism predicts that when crowding is weak for one feature and strong for the other that crowding should be all-or-none for both. In contrast, when crowding was weak for colour and strong for motion, errors were reduced for colour but remained for motion, and vice versa with weak motion and strong colour crowding. This double dissociation reveals that crowding disrupts certain combinations of visual features in a feature-specific manner, ruling out a singular object-selective mechanism. The ability to recognise one aspect of a cluttered scene, like colour, thus offers no guarantees for the correct recognition of other aspects, like motion.Significance statementOur peripheral vision is primarily limited by crowding, the disruption to object recognition that arises in clutter. Crowding is widely assumed to be a singular process, affecting all of the features (orientation, motion, colour, etc.) within an object simultaneously. In contrast, we observe a double dissociation whereby observers make errors regarding the colour of a crowded object whilst correctly judging its direction, and vice versa. This dissociation can be reproduced by a population-coding model where the direction and hue of target/flanker elements are pooled independently. The selective disruption of some object features independently of others rules out a singular crowding mechanism, posing problems for high-level crowding theories, and suggesting that the underlying mechanisms may be distributed throughout the visual system.

scholarly journals A summary-statistic representation in peripheral vision explains visual crowding

2009 ◽  
Vol 9 (12) ◽  
pp. 13-13 ◽  
Author(s):  
B. Balas ◽  
L. Nakano ◽  
R. Rosenholtz
Keyword(s):  
Peripheral Vision ◽  
Summary Statistic ◽  
Visual Crowding

Microsurgically generated discontinuities provoke heritable changes in cellular handedness of a ciliate, Stylonychia mytilus

Development ◽  
1991 ◽  
Vol 111 (2) ◽  
pp. 337-356
Author(s):  
X.B. Shi ◽  
Z.I. Qiu ◽  
W. He ◽  
J. Frankel
Keyword(s):  
Large Scale ◽  
Mirror Image ◽  
The Other ◽  
Left Edge ◽  
Left Handed ◽  
Specific Manner ◽  
The Right ◽  
Anteroposterior Polarity ◽  
Posterior Anterior ◽  
Stylonychia Mytilus

Stylonychia mytilus is a dorsoventrally flattened ciliate with compound ciliary structures arranged in a specific manner on the cell surface. In mirror-image (MI) doublets of this ciliate, two nearly complete sets of ciliary structures are arrayed side-by-side, one in a normal or ‘right-handed’ (RH) arrangement, the other in a reversed or ‘left-handed’ (LH) arrangement. MI-doublets exist in two forms, one with the RH component on the right, the LH component on the left, and feeding structures near the center (‘buccal-adjoining MI-doublet’); the other with the RH component on the left, the LH component on the right, and feeding structures on the lateral edges (‘buccal-opposing MI-doublet’). We describe an operation that can generate either type of MI-doublet. This operation interchanges large anterior and posterior regions of the cell, transposing the original posterior region anteriorly (P—A) and the original anterior region posteriorly (A—P), while retaining the original anteroposterior polarity of each region. Two sets of new ciliary structures then are formed in mirror-image arrangement, with the set in the P—A region oriented normally and the set in the A—P region undergoing a reversal of polarity along its anteroposterior axis. This sometimes creates end-to-end MI forms, but more commonly produces side-by-side MI-doublets through a folding together of the P—A and A—P regions. This folding occurs because one lateral edge of the cell had been removed during the operation; if the left edge was removed, the complex folds to the left and forms a buccal-adjoining MI-doublet, whereas if the right edge was removed, the complex folds to the right and forms a buccal-opposing MI-doublet. Both types can reorganize and later divide true-to-type, although the ‘buccal-opposing’ type is by far the more stable of the two. The generation of mirror-image forms is dependent on the prior abnormal juxtaposition of regions from opposite ends of the cell, and involves a coordinated respecification of large-scale organization. We interpret this response to be a consequence of intercalation of missing intervening positional values in the zone of posterior-anterior abutment.

scholarly journals The affective economy of transnational surrogacy

2018 ◽  
Vol 50 (8) ◽  
pp. 1626-1645 ◽  
Author(s):  
Carolin Schurr ◽  
Elisabeth Militz
Keyword(s):  
Economic Sociology ◽  
Global South ◽  
The Other ◽  
Market Making ◽  
Ethnographic Fieldwork ◽  
Final Good ◽  
Multiple Processes ◽  
Maternal Bond ◽  
Effective Organization ◽  
Global Surrogacy

The booming business of global surrogacy has come to a halt: one surrogacy hub after the other has started to regulate the incremental flow of intended parents to the Global South hoping to fulfill their desire for a baby with the help of a foreign surrogate laborer. Thailand and Nepal have banned surrogacy altogether; India and Mexico insist on the altruistic nature of their surrogacy arrangements. As the drive for altruistic surrogacy suggests, the baby holds an exceptional position in many societies: ideas about the ‘unique’ maternal bond create public unease about the commercialization of babies in surrogacy markets. Drawing on economic sociology and theories of affect, this paper argues that multiple processes of affective attachment, detachment and reattachment shape transnational surrogacy journeys. Based on ethnographic fieldwork in Mexico’s surrogacy industry, the paper studies processes of commodification and decommodification in three instances of market-making: (1) the assignment of value and a price to reproductive laborers’ bodies on the basis of affective postcolonial geographies of beauty; (2) the affective/effective organization of the market encounter through contracts and communication rules and (3) the detachment of the final ‘good’ of the baby from the surrogate laborer. Transnational surrogacy arrangements, the paper concludes, are always forms of partial commodification – no matter whether they are framed as altruistic or commercial – because processes of affective/effective attachment and detachment are fundamental for delineating the intimate boundaries of families that come into life with the assistance of the globally operating surrogacy industry.

Now you see it, now you don’t: Design dependent sound symbolism effect in categorization studies

2012 ◽  
Vol 25 (0) ◽  
pp. 65 ◽  
Author(s):  
Vanja Kovic ◽  
Jovana Pejovic
Keyword(s):  
Mental Image ◽  
Visual Stimuli ◽  
Sound Symbolism ◽  
The Other ◽  
Visual Features ◽  
General Process ◽  
Visual Objects ◽  
The One ◽  
Label Object ◽  
Is Design

A number of studies have demonstrated sound-symbolism effects in adults and in children. Moreover, recently, ERP studies have shown that the sensitivity to sound-symbolic label–object associations occurs within 200 ms of object presentation (Kovic et al., 2010). It was argued that this effect may reflect a more general process of auditory–visual feature integration where properties of auditory stimuli facilitate a mapping to specific visual features. Here we demonstrate that the sound-symbolism effect is design dependent, namely — it occurs only when mapping from auditory to visual stimuli and not vice verse. Two groups of participants were recruited for solving the categorization task. They were presented them with 12 visual stimuli, half of which were rounded and another half of angular shapes. One group was trained to classify the rounded objects as ‘takete’ and the rounded ones as ‘maluma’, whereas the other group mapped ‘takete’ to rounded and ‘maluma’ to angular shapes. Moreover, half of these two groups heard the label before seeing the objects, whereas the other half was given the label after perceiving the object. The results revealed the sound-symbolism effect only in the group which was trained on the auditory–visual objects mapping and not in the one trained on the visual–auditory mappings. Thus, despite the previous findings we demonstrate that the sound-symbolism effect is not significant per se, but design-dependent and we argue that the sound brings up a mental image that is more constrained than the sounds brought up by a picture.

scholarly journals The role of Peripheral Vision in the Flashed Face Distortion Effect

Perception ◽  
2018 ◽  
Vol 48 (1) ◽  
pp. 93-101
Author(s):  
Jamie Bowden ◽  
David Whitaker ◽  
Matt J. Dunn
Keyword(s):  
Visual Acuity ◽  
Analogue Scale ◽  
Peripheral Vision ◽  
Crowding Effect ◽  
Visual Periphery ◽  
Peripheral Location ◽  
Distortion Effect ◽  
Optical Defocus ◽  
Visual Crowding

The flashed face distortion effect is a phenomenon whereby images of faces, presented at 4–5 Hz in the visual periphery, appear distorted. It has been hypothesized that the effect is driven by cortical, rather than retinal, components. Here, we investigated the role of peripheral viewing on the effect. Normally sighted participants viewed the stimulus peripherally, centrally, and centrally with a blurring lens (to match visual acuity in the peripheral location). Participants rated the level of distortion using a Visual Analogue Scale. Although optical defocus did have a significant effect on distortion ratings, peripheral viewing had a much greater effect, despite matched visual acuity. We suggest three potential mechanisms for this finding: increased positional uncertainty in the periphery, reduced deployment of attention to the visual periphery, or the visual crowding effect.

scholarly journals The Cucumber vein yellowing virus Silencing Suppressor P1b Can Functionally Replace HCPro in Plum pox virus Infection in a Host-Specific Manner

2012 ◽  
Vol 25 (2) ◽  
pp. 151-164 ◽  
Author(s):  
Alberto Carbonell ◽  
Gabriela Dujovny ◽  
Juan Antonio García ◽  
Adrian Valli
Keyword(s):  
Rna Silencing ◽  
Deleterious Effect ◽  
Prunus Persica ◽  
Plant Viruses ◽  
Natural Host ◽  
Plum Pox Virus ◽  
Silencing Suppressor ◽  
Specific Manner ◽  
Silencing Suppression ◽  
Yellowing Virus

Plant viruses of the genera Potyvirus and Ipomovirus (Potyviridae family) use unrelated RNA silencing suppressors (RSS) to counteract antiviral RNA silencing responses. HCPro is the RSS of Potyvirus spp., and its activity is enhanced by the upstream P1 protein. Distinctively, the ipomovirus Cucumber vein yellowing virus (CVYV) lacks HCPro but contains two P1 copies in tandem (P1aP1b), the second of which functions as RSS. Using chimeras based on the potyvirus Plum pox virus (PPV), we found that P1b can functionally replace HCPro in potyviral infections of Nicotiana plants. Interestingly, P1a, the CVYV protein homologous to potyviral P1, disrupted the silencing suppression activity of P1b and reduced the infection efficiency of PPV in Nicotiana benthamiana. Testing the influence of RSS in host specificity, we found that a P1b-expressing chimera poorly infected PPV's natural host, Prunus persica. Conversely, P1b conferred on PPV chimeras the ability to replicate locally in cucumber, CVYV's natural host. The deleterious effect of P1a on PPV infection is host dependent, because the P1aP1b-expressing PPV chimera accumulated in cucumber to higher levels than PPV expressing P1b alone. These results demonstrate that a potyvirus can use different RSS, and that particular RSS and upstream P1-like proteins contribute to defining the virus host range.

scholarly journals Transsaccadic integration operates independently in different feature dimensions

2021 ◽  
Author(s):  
Garry Kong ◽  
David Aagten-Murphy ◽  
Jessica MV McMaster ◽  
Paul M Bays
Keyword(s):  
Visual System ◽  
Peripheral Vision ◽  
Probability Of Detection ◽  
Visual Input ◽  
The Other ◽  
Feature Change ◽  
Observer Model ◽  
Transsaccadic Integration ◽  
Gaze Fixations

Our knowledge about objects in our environment reflects an integration of current visual input with information from preceding gaze fixations. Such a mechanism may reduce uncertainty, but requires the visual system to determine which information obtained in different fixations should be combined or kept separate. To investigate the basis of this decision, we conducted three experiments. Participants viewed a stimulus in their peripheral vision, then made a saccade that shifted the object into the opposite hemifield. During the saccade, the object underwent changes of varying magnitude in two feature dimensions (Experiment 1: color and location, Experiments 2 and 3: color and orientation). Participants reported whether they detected any change and estimated one of the post-saccadic features. Integration of pre-saccadic with post-saccadic input was observed as a bias in estimates towards the pre-saccadic feature value. In all experiments, pre-saccadic bias weakened as the magnitude of the transsaccadic change in the estimated feature increased. Changes in the other feature, despite having a similar probability of detection, had no effect on integration. Results were quantitatively captured by an observer model where the decision whether to integrate information from sequential fixations is made independently for each feature and coupled to awareness of a feature change.

Spatial Attention Enhances Crowded Stimulus Encoding across Modeled Receptive Fields by Increasing Redundancy of Feature Representations

2021 ◽  
pp. 1-29
Author(s):  
Justin D. Theiss ◽  
Joel D. Bowen ◽  
Michael A. Silver
Keyword(s):  
Spatial Attention ◽  
Spatial Resolution ◽  
Receptive Fields ◽  
Visual Features ◽  
Target Classification ◽  
Dynamic Changes ◽  
Feature Representations ◽  
Feature Interactions ◽  
Spatial Locations ◽  
Visual Crowding

Abstract Any visual system, biological or artificial, must make a trade-off between the number of units used to represent the visual environment and the spatial resolution of the sampling array. Humans and some other animals are able to allocate attention to spatial locations to reconfigure the sampling array of receptive fields (RFs), thereby enhancing the spatial resolution of representations without changing the overall number of sampling units. Here, we examine how representations of visual features in a fully convolutional neural network interact and interfere with each other in an eccentricity-dependent RF pooling array and how these interactions are influenced by dynamic changes in spatial resolution across the array. We study these feature interactions within the framework of visual crowding, a well-characterized perceptual phenomenon in which target objects in the visual periphery that are easily identified in isolation are much more difficult to identify when flanked by similar nearby objects. By separately simulating effects of spatial attention on RF size and on the density of the pooling array, we demonstrate that the increase in RF density due to attention is more beneficial than changes in RF size for enhancing target classification for crowded stimuli. Furthermore, by varying target and flanker spacing, as well as the spatial extent of attention, we find that feature redundancy across RFs has more influence on target classification than the fidelity of the feature representations themselves. Based on these findings, we propose a candidate mechanism by which spatial attention relieves visual crowding through enhanced feature redundancy that is mostly due to increased RF density.

scholarly journals Antioxidative and antiphotoaging activities of neferine upon UV-A irradiation in human dermal fibroblasts

2018 ◽  
Vol 38 (6) ◽  
Author(s):  
Abidullah khan ◽  
Hongliang Bai ◽  
Maoguo Shu ◽  
Mingxia Chen ◽  
Amin Khan ◽  
...  
Keyword(s):  
Deleterious Effect ◽  
Dermal Fibroblasts ◽  
The Other ◽  
Oxygen Species ◽  
Human Dermal Fibroblasts ◽  
Ultraviolet A ◽  
Enzymatic Antioxidant ◽  
Matrix Metalloproteinase 1 ◽  
Prevention And Treatment ◽  
Skin Photoaging

Our daily exposure to ultraviolet radiation (UVR) results in the production of reactive oxygen species (ROS), lipids, proteins and DNA damage and alteration in fibroblast structure, thus contributing to skin photoaging. For this reason, the use of natural bioactive compounds with antioxidant activity could be a strategic tool to overcome ultraviolet A (UV-A) induced deleterious effect. Neferine is an alkaloid extract from the seed embryos of lotus (Nelumbo nucifera Gaertn). In the present study, we report the protective effect of neferine against UV-A induced oxidative stress and photoaging in human dermal fibroblasts (HDFs). HDFs subjected to UV-A irradiation showed increased production of ROS and malondialdehyde (MDA). Furthermore, it depleted the cellular enzymatic antioxidant superoxide dismutase (SOD) and non-enzymatic antioxidant glutathione peroxidase (GPx). On the other hand, HDFs treated with neferine followed by UV-A irradiation reversed the process, reduced the ROS and lipid peroxidation and restored the antioxidants pool. Moreover, neferine treatment significantly inhibited UV-A induced matrix metalloproteinase-1 (MMP-1) expression in HDFs. Remarkable morphological and ultrastructural alterations observed in HDFs upon UV-A irradiation, were also reduced with neferine treatment. Taken together, our results suggest that neferine has strong antioxidative and photoprotective properties and thus may be a potential agent for the prevention and treatment of UV-A mediated skin photoaging.

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