Visual Selection Research Articles

Following the gold trail: Reward influences on spatial exploration in neglect

Spatial attention is guided by the perceived salience and relevance of objects in the environment, a process considered to depend on a broad parieto-frontal cortical network. Signals arising from the limbic and nigrostriatal pathways conveying affective and motivational cues are also known to modulate visual selection, but the nature of this contribution and its relation to spatial attention remain unclear. We investigated the role of reward information in 15 patients with left hemispatial neglect and 15 control subjects playing multiple rounds of a virtual foraging game. Participants’ exploration tracked dynamically adjusted underlying reward distributions, largely unbeknownst to them. Both control and neglect participants showed typical exploration/exploitation balance, dependent on abundance or scarcity of rewards. De-reinforcing previously favored, mostly right, regions of space attenuated left space under-exploration in patients. Multiple regression analysis indicates that such reward-based training may benefit mostly patients early after lesion onset, with mild neglect and small lesions sparing subcortical regions. Our findings support the view that spatial exploration recruits heavily right hemispheric visuospatial attentional mechanisms as well as reward signals processed by basal ganglia and prefrontal cortical circuits, which serve to learn about the motivational relevance of environmental stimuli and help prioritize attention and motor response selection.

Sala de referência ideal para as crianças e para as profissionais da educação

Este artigo tem como objetivo principal compreender os anseios e as idealizações das crianças e dos profissionais, em relação ao espaço da sala de referência, na Educação Infantil. A pesquisa, de abordagem qualitativa, envolveu discussões sobre espaço, ambiente e lugar, com ênfase na Educação Infantil. Enquadrou-se nas características do estudo de caso e teve como campo de investigação uma sala de pré-escola II de uma instituição pública em Presidente Prudente (SP). Os sujeitos foram dezoito crianças e três profissionais que atuavam na instituição. O procedimento de recolha de dados foi a observação do espaço, com registro escrito e fotográfico, e a seleção visual. As conclusões apontaram que os anseios das crianças divergem em alguns aspectos dos educadores. Constata-se, também, que as profissionais têm conhecimentos alinhados às concepções apontadas por teóricos que estudam a organização do espaço das instituições de Educação Infantil, porém, esses saberes são pouco materializados na prática.

A Causal Role for Mouse Superior Colliculus in Visual Perceptual Decision-Making.

The superior colliculus (SC) is arguably the most important visual structure in the mouse brain and is well known for its involvement in innate responses to visual threats and prey items. In other species, the SC plays a central role in voluntary as well as innate visual functions, including crucial contributions to selective attention and perceptual decision-making. In the mouse, the possible role of the SC in voluntary visual choice behaviors has not been established. Here, we demonstrate that the mouse SC of both sexes plays a causal role in visual perceptual decision-making by transiently inhibiting SC activity during an orientation change detection task. First, unilateral SC inhibition-induced spatially specific deficits in detection. Hit rates were reduced, and reaction times increased for orientation changes in the contralateral but not ipsilateral visual field. Second, the deficits caused by SC inhibition were specific to a temporal epoch coincident with early visual burst responses in the SC. Inhibiting SC during this 100-ms period caused a contralateral detection deficit, whereas inhibition immediately before or after did not. Third, SC inhibition reduced visual detection sensitivity. Psychometric analysis revealed that inhibiting SC visual activity significantly increased detection thresholds for contralateral orientation changes. In addition, effects on detection thresholds and lapse rates caused by SC inhibition were larger in the presence of a competing visual stimulus, indicating a role for the mouse SC in visual target selection. Together, our results demonstrate that the mouse SC is necessary for the normal performance of voluntary visual choice behaviors.SIGNIFICANCE STATEMENT The mouse superior colliculus (SC) has become a popular model for studying the circuit organization and development of the visual system. Although the SC is a fundamental component of the visual pathways in mice, its role in visual perceptual decision-making is not clear. By investigating how temporally precise SC inhibition influenced behavioral performance during a visually guided orientation change detection task, we identified a 100-ms temporal epoch of SC visual activity that is crucial for the ability of mice to detect behaviorally relevant visual changes. In addition, we found that SC inhibition also caused deficits in visual target selection. Thus, our findings highlight the importance of the SC for visual perceptual choice behavior in the mouse.

Variable Penetrance among Different Sources of the Male Fertility Restoration Allele of Onion

Hybrid onion (Allium cepa) seed is produced using cytoplasmic male sterility (CMS). For the most commonly used source of onion CMS, male fertile plants possess male sterile (S) cytoplasm and dominant allele(s) at one nuclear male fertility locus (Ms). Because male fertility restoration is not necessary for bulb production, it is desirable to purge dominant alleles at Ms from populations and breeding lines to facilitate the development of male sterile inbreds for hybrid production. In this research, we used molecular markers to establish the cytoplasms and genotypes at Ms in progenies from testcrosses of male sterile lines with plants from three populations [B2354, Ailsa Craig (AC), and Sapporo-Ki (Ski)] possessing the dominant Ms allele. We scored male fertility of testcross progenies by visual examination of flowers and acetocarmine staining of pollen. Different sources of the dominant Ms allele showed significantly different amounts of male fertility restoration and proportions of stainable pollen, complicating visual selection against the dominant Ms allele. For AC and Ski, molecular markers correctly predicted male sterility vs. male fertility of progenies in the greenhouse and field. However, for B2354, male fertility restoration was less clear and especially difficult to score under field conditions, consistent with reduced penetrance of male fertility restoration for this source of the dominant Ms allele. These results will be of interest to onion breeders selecting S-cytoplasmic male sterile lines for hybrid onion development.

Diagnóstico das técnicas de produção e armazenamento de sementes crioulas em assentamentos rurais de Aparecida, Paraíba, Brasil

Produzir e armazenar sementes crioulas é uma prática adotada por muitas famílias de agricultores que permite ganhos socioambientais e mantêm a identidade cultural das comunidades rurais tradicionais. Objetivou-se com este trabalho avaliar a formas de produção e de armazenamento das sementes crioulas por famílias agricultoras residentes em assentamentos rurais da reforma agrária em Aparecida – PB. A pesquisa teve caráter quantiqualitativo, utilizando-se como instrumento para coleta de dados um questionário semiestruturado a respeito do perfil social dos agricultores, das técnicas de produção e armazenamento de sementes além de uma listagem das sementes comumente utilizadas. Com base nos dados observados pode-se evidenciar a importância socioambiental da manutenção das sementes crioulas pelos agricultores. Constatou-se, também, que as formas de produção são de caráter agroecológico em sistemas manual de semeadura e consorciado de plantio. O preparo das sementes é do tipo artesanal e consiste na seleção visual das sementes, seguidas de secagem ao ar livre e posterior armazenamento em garrafas PET’s recicladas.

Attentional selection is biased towards controllable stimuli.

While the factors that contribute to individuals feeling a sense agency over a stimulus have been extensively studied, the cognitive effects of a sense of agency over a stimulus are little known. Here, we conducted three experiments examining whether attentional selection is biased towards controllable stimuli. In all three experiments, participants moved four circle stimuli, one of which was under their control. A search target then appeared on one of the stimuli. In Experiment 1, the target was always on the controlled stimulus, but we manipulated the degree of control the participant had. In Experiment 2, the controlled stimulus was the target on 50% of the trials. In Experiment 3, we used a central arrow cue to tell participants which arrow key to press (rather than using a free choice task) and made the controlled stimulus the target on 25% of the trials, making it nonpredictive of the target's location. Across the three experiments we found that visual selection was biased towards controllable stimuli. This attentional bias was larger when participants had full, rather than partial, control over the stimulus, indicating that sense of agency leads one to prioritize objects under their control. The fact that agency influenced attention when the controlled object contained the target in 100%, 50%, and 25% of trials, and occurred even when participants needed to monitor the center of the display in order to know which arrow key to press, suggests that its influence does not depend on task relevance or volitional decision-making.

Estimation With Fast Feature Selection in Robot Visual Navigation

We consider the robot localization problem with sparse visual feature selection. The underlying key property is that contributions of trackable features (landmarks) appear linearly in the information matrix of the corresponding estimation problem. We utilize standard models for motion and vision system using a camera to formulate the feature selection problem over moving finite-time horizons. We propose a scalable randomized sampling algorithm to select more informative features to obtain a certain estimation quality. We provide probabilistic performance guarantees for our method. The time-complexity of our feature selection algorithm is linear in the number of candidate features, which is practically plausible and outperforms existing greedy methods that scale quadratically with the number of candidate features. Our numerical simulations confirm that not only the execution time of our proposed method is comparably less than that of the greedy method, but also the resulting estimation quality is very close to the greedy method.

Effects of different light sources on tooth shade selection.

Differences in lighting conditions can make matching the shade of a single porcelain tooth to the natural adjacent teeth very challenging. The purpose of the study was to examine visual shade selection under 3 different light sources - natural daylight, a dental operating light and a color-corrected light. The visual assessment was based on a comparison between a shade guide and the target tooth. One observer with normal color vision was asked to visually match the color of the maxillary central right incisor and the maxillary right canine in a group of 100 subjects, aged 22-40 years. Two shade guides were used - VITA Vitapan Classical® and VITA 3D Master® - in natural daylight as well as under an operating light and a handheld light (Demetron Shade Light®). The VITA Easyshade® spectrophotometer was used to evaluate the results of the visual shade selection method. Significant differences were found between the effects of using the shade guide systems (p < 0.05) and light sources (p < 0.05). Overall, the use of the Vitapan Classical shade guide significantly improved the correlation between visual matching and the spectrophotometer readings. Within the limitations of this study, the Vitapan Classical shade guide demonstrated superior agreement in shade selection as compared to the 3D Master shade guide. The Demetron Shade Light was proven to be a useful device for the color matching of artificial teeth in prosthodontic treatment. Visual tooth color matching is a subjective method and it produces the best results under a color-matching light.

Covert Spatial Attention Speeds Target Individuation.

Covert spatial attention has long been thought to speed visual processing. Psychophysics studies have shown that target information accrues faster at attended locations than at unattended locations. However, with behavioral evidence alone, it is difficult to determine whether attention speeds visual processing of the target or subsequent postperceptual stages of processing (e.g., converting sensory responses into decision signals). Moreover, although many studies have shown that attention can boost the amplitude of visually evoked neural responses, no robust effect has been observed on the latency of those neural responses. Here, we offer new evidence that may reconcile the neural and behavioral findings. We examined whether covert attention influenced the latency of the N2pc component, an electrophysiological marker of visual selection that has been linked with object individuation-the formation of an object representation that is distinct from the background and from other objects in the scene. To this end, we manipulated whether or not human observers (male and female) covertly attended the location of an impending search target. We found that the target evoked N2pc onset ∼20 ms earlier when the target location was cued than when it was not cued. In a second experiment, we provided a direct replication of this effect, confirming that the effect of attention on N2pc latency is robust. Thus, although attention may not speed the earliest stages of sensory processing, attention does speed the critical transition between raw sensory encoding and the formation of individuated object representations.SIGNIFICANCE STATEMENT Covert spatial attention improves processing at attended locations. Past behavioral studies have shown that information about visual targets accrues faster at attended than at unattended locations. However, it has remained unclear whether attention speeds perceptual analysis or subsequent postperceptual stages of processing. Here, we present robust evidence that attention speeds the N2pc, an electrophysiological signal that indexes the formation of individuated object representations. Our findings show that attention speeds a relatively early stage of perceptual processing while also elucidating the specific perceptual process that is speeded.

Selective sweeps on novel and introgressed variation shape mimicry loci in a butterfly adaptive radiation.

Natural selection leaves distinct signatures in the genome that can reveal the targets and history of adaptive evolution. By analysing high-coverage genome sequence data from 4 major colour pattern loci sampled from nearly 600 individuals in 53 populations, we show pervasive selection on wing patterns in the Heliconius adaptive radiation. The strongest signatures correspond to loci with the greatest phenotypic effects, consistent with visual selection by predators, and are found in colour patterns with geographically restricted distributions. These recent sweeps are similar between co-mimics and indicate colour pattern turn-over events despite strong stabilising selection. Using simulations, we compare sweep signatures expected under classic hard sweeps with those resulting from adaptive introgression, an important aspect of mimicry evolution in Heliconius butterflies. Simulated recipient populations show a distinct ‘volcano’ pattern with peaks of increased genetic diversity around the selected target, characteristic of sweeps of introgressed variation and consistent with diversity patterns found in some populations. Our genomic data reveal a surprisingly dynamic history of colour pattern selection and co-evolution in this adaptive radiation.

Automated Methods for Detecting Volcanic Deformation Using Sentinel‐1 InSAR Time Series Illustrated by the 2017–2018 Unrest at Agung, Indonesia

AbstractRadar satellites, such as Sentinel‐1, are now able to produce time series of ground deformation at any volcano around the world, but atmospheric effects still limit the real‐time detection of unrest at tropical volcanoes. Here, we test two approaches to correct atmospheric errors—phase elevation correlations and global weather models—and assess the ability of Interferometric Synthetic Aperture Radar (InSAR) time series to detect deformation anomalies using either a fixed threshold or a cumulative sum control chart. We use the 2017–2018 crisis at Agung volcano as a case example because strong atmospheric signals were originally misidentified as true deformation, and obscured the subtle deformation pattern associated with magmatic activity. We assess the Receiver Operating Characteristics (ROC) of each method and found the average area under the ROC curve to be about 0.5 for the uncorrected data (corresponding to no discrimination capability), around 0.8 after combined atmospheric corrections (weather model and phase elevation approaches), and more than 0.95 using a cumulative sum control chart (where 1 corresponds to ideal separation between classes). Our results retrospectively show that uplift could have been detected to a 95% level of confidence for both ascending and descending time series by October 2017, 15 days after the start of the seismic swarm and 1 month prior to the eruption. Thus, our approach successfully flags anomalous behavior without relying on visual inspection or selection of an arbitrary threshold, and hence shows potential as a monitoring tool for volcano observatories globally.

Visual preference of flower‐visiting crab spiders (Ebrechtella tricuspidata) for host flowers

1. Crab spiders (Thomisidae) are common flower‐visiting spiders that ambush prey on inflorescences. As such, they require specific flowers or substrates for hunting, which are most often selected using sensory cues (e.g. vision). However, few studies have examined the visual preference of crab spiders for particular flowers. In this study, the visual preferences of the crab spider Ebrechtella tricuspidata for different inflorescence characteristics (e.g. colour and shape) were investigated.2. The results showed that adult spiders explored all colours and shapes, whereas juvenile spiders displayed an overall preference for long (red) and short (purple) wavelength colours. Thus, differences in colour were not particularly important for E. tricuspidata with regard to visual attractiveness and selection.3. However, inflorescence shape (e.g. tulip) was found to be a more desirable trait for selection, which was probably due to the provision of shelter.4. These results also suggest that male preference for female spiders depended somewhat on the background colour (wavelength) of the flower on which the female was located.

Biolistic DNA Delivery in Turfgrass Embryonic Callus Initiated from Mature Seeds.

We describe a protocol for the establishment and preparation of creeping bentgrass (Agrostis stolonifera L.) cultivar "Penn A-4" embryonic calli, biolistic transformation, selection, and regeneration of transgenic plants. The embryonic callus is initiated from mature seeds, maintained by visual selection under the dissecting microscope and subjected to bombardment with plasmid DNA containing a bialaphos-resistance (bar) gene. PCR, Southern, and Northern blot analyses are used to confirm the transgene integration and expression.

Approach and avoidance movements modulate value-driven attentional capture.

Recent studies have shown that visual features that were previously associated with a high monetary reward attract visual attention, a finding referred to as value-driven attentional capture. Given the fact that a reward often follows an action, the present study examined how approach and avoidance movements made to achieve a reward might modulate value-driven attentional capture. Experiment 1 revealed that a color that was previously associated with a high reward was more likely to capture visual attention than a color that was previously associated with a low reward, but only when the reward had been achieved by an approaching movement. In contrast, when the reward had been achieved by an avoiding movement, a color that was associated with a low reward was more likely to capture attention than a color that was associated with a high reward. Experiment 2 replicated the key findings of Experiment 1. Experiment 3 showed that approaching and avoiding movements do not modulate attentional capture on their own, in the absence of any reward. Overall, the present study revealed for the first time that visual features that were previously associated with compatible action and reward pairs prioritize visual selection. These novel findings show how the history of action and reward interactively modulates visual selection. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Perception and practices with regard to tooth shade selection for composite restoration among dentists in Southwest, Nigeria

Background: The perception of tooth color is an important goal for the dentist who needs to choose the right tooth shade to create satisfactory esthetic restorations as well as for the patient who desires a better smile. The success of any tooth-colored (anterior) restoration is however directly related to the accuracy of chairside shade selection The aim of this study was to determine the knowledge and practices of dentists on shade selection in composite restorations in Southwest, Nigeria. Materials and Methods: This descriptive self-administered questionnaire-based study was conducted among 200 randomly enlisted dentists selected by multistage sampling in the Southwest of Nigeria. Chi-square statistical test was utilized for categorical variables, while the independent t-test was used to compare the mean values in subgroups. A multivariate linear regression model was used to assess the association between predictor variables and knowledge scores. The level of significance in this study was set at 0.05. Results: Majority of respondents had good knowledge (67.5%), while 60.5% of them had good practices. The highest proportion (66.5%) used only visual shade selection in natural daylight (89.0%), while only 48% determine the tooth shade at the cervical, middle, and incisal third of the tooth; 73% had never taken a color blind test. Dentists had practiced for more than 10 years and restorative dentistry consultants had significantly better knowledge about shade selection. Respondents who had poor knowledge had significantly poorer shade selection practices (P = 0.036). After controlling for confounders by multivariate logistic regression, all categories of dentists with good knowledge and consultants still had significantly better dental shade selection practices. Conclusion: Experienced dentists and restorative consultants appear to have adequate knowledge about shade selection and this had a significant impact on their practice. A need however exists to bridge the gap among other categories of dental personnel to improve the esthetic outcome of composite restorations.

Visual Navigation Features Selection Algorithm Based on Instance Segmentation in Dynamic Environment

Ego-motion estimation, as one of the core technologies of unmanned systems, is widely used in autonomous robot navigation, unmanned driving, augmented reality and other fields. With the development of computer vision, there has been considerable interest in ego-motion estimation with visual navigation. One of the core technologies in Visual navigation is using the matching feature points between consecutive image frames to estimate pose. Since the feature-based method performed under the assumption of a static environment, it susceptive to the dynamic targets. Visual navigation in the dynamic environment has become an important research issue. This paper proposed a practical and robust features selection algorithm of visual navigation which avoids using the feature points on dynamic objects. Firstly, according to the instance segmentation of deep neural network, the objects are classified into potential dynamic and static categories. Subsequently, the matching features on the potential moving objects are used to update vehicle state respectively, meanwhile, the relevant reprojection error of other feature points on the background could be calculated. Eventually, the result of whether the target is moving or not will be judged by the reprojection error, and the features on dynamic targets are removed. To illustrate the effectiveness of the features selection method in the dynamic environment, the proposed algorithm is merged into an MSCKF based on tri-focal tensor geometry, and it has been evaluated in a public dataset. Experimental results demonstrated the effectiveness of the proposed method.

Perceptual grouping constrains inhibition in time-based visual selection

In time-based visual selection, task-irrelevant, old stimuli can be inhibited in order to allow the selective processing of new stimuli that appear at a later point in time (the preview benefit; Watson & Humphreys, 1997). The current study investigated if illusory and non-illusory perceptual groups influence the ability to inhibit old and prioritize new stimuli in time-based visual selection. Experiment 1 showed that with Kanizsa-type illusory stimuli, a preview benefit occurred only when displays contained a small number of items. Experiment 2 demonstrated that a set of Kanizsa-type illusory stimuli could be selectively searched amongst a set of non-illusory distractors with no additional preview benefit obtained by separating the two sets of stimuli in time. Experiment 3 showed that, similarly to Experiment 1, non-illusory perceptual groups also produced a preview benefit only for a small number of number of distractors. Experiment 4 demonstrated that local changes to perceptually grouped old items eliminated the preview benefit. The results indicate that the preview benefit is reduced in capacity when applied to complex stimuli that require perceptual grouping, regardless of whether the grouped elements elicit illusory contours. Further, inhibition is applied at the level of grouped objects, rather than to the individual elements making up those groups. The findings are discussed in terms of capacity limits in the inhibition of old distractor stimuli when they consist of perceptual groups, the attentional requirements of forming perceptual groups and the mechanisms and efficiency of time-based visual selection.

Estabilidad y adaptación del rendimiento y calidad de tortilla en maíz Tuxpeño, Valles-Altos

La variedad V-520C de maíz (Zea mays L.) pertenece a la raza Tuxpeño, es originaria de Veracruz (500 msnm) y fue adaptada a los Valles Altos de México (&gt;2 200 msnm) con selección masal visual (SMV) recurrentemente durante 19 ciclos. El objetivo fue evaluar la estabilidad y la adaptación de V-520C original (C0) y los materiales adaptados ciclo 14 (C14) y ciclo 19 (C19) para el rendimiento de grano y calidad de tortilla mediante sitios de regresión (SREG). Entre 2013 y 2014 se evaluaron tres genotipos C0, C14 y C19 en un diseño bloques completos al azar con tres repeticiones. Las evaluaciones se realizaron en el Estado de México y Veracruz con tres experimentos por entidad. El análisis de varianza detectó significancia (p≤ 0.01) entre ambientes, genotipos y la interacción genotipo-ambiente y en los dos primeros componentes principales para las seis variables. SREG indica que C19 tuvo mejor adaptación y estabilidad en rendimiento de grano (3.54 t ha-1), humedad de tortilla a las 24 h (42.72%), rendimiento de tortilla fría (1.44 kg kg-1 maíz) y una fuerza reducida para romper la tortilla (193 gf). La SMV produjo cambios favorables al C19, que tuvo mejor estabilidad y adaptación en Valles Altos de México. Siendo el ambiente Montecillo 2014-PV, el que discriminó entre genotipos y mejor mega-ambiente en las variables. Todos los genotipos y ambientes, con excepción de Tepetates 2014-OI y Coatlinchán 2014-PV, cumplieron con los parámetros requeridos por la norma NMX-034/1 para maíces destinados al proceso de nixtamalización.

Oscillatory Control over Representational States in Working Memory.

In the visual world, attention is guided by perceptual goals activated in visual working memory (VWM). However, planning multiple-task sequences also requires VWM to store representations for future goals. These future goals need to be prevented from interfering with the current perceptual task. Recent findings have implicated neural oscillations as a control mechanism serving the implementation and switching of different states of prioritization of VWM representations. We review recent evidence that posterior alpha-band oscillations underlie the flexible activation and deactivation of VWM representations and that frontal delta-to-theta-band oscillations play a role in the executive control of this process. That is, frontal delta-to-theta appears to orchestrate posterior alpha through long-range oscillatory networks to flexibly set up and change VWM states during multitask sequences.

Allocation of attention in 3D space is adaptively modulated by relative position of target and distractor stimuli.

Allocation of attention across different depth planes is a prerequisite for visual selection in a three-dimensional environment. Previous research showed that participants successfully used stereoscopic depth information to focus their attention. This, however, does not mean that salient information from other depth planes is completely neglected. The present study investigated the question of whether competing visual information is differentially processed when displayed in a single depth plane or across two different depth planes. Moreover, it was of interest whether potential effects were further modulated by the items' relative spatial position (near or far). In three experiments participants performed a variant of the additional singleton paradigm. Targets were defined by stereoscopic depth information and as such appeared either in a near or far depth plane. Distractor stimuli were displayed in the same or in the opposed depth plane. The results consistently showed that visual selection was slower when target and distractor coincided within the same depth plane. There was no general advantage for targets presented in near or far depth planes. However, differential effects of target depth plane and the target-distractor relation were observed. Selection of near targets was more affected by distractors within the same depth plane while far targets were identified more slowly when the amount of information in closer depth planes increased. While attentional resources could not be exclusively centered to a distinct depth plane, the allocation of attention might be organized along an egocentric gradient through space and varies with the organization of the visual surrounding.