Color Cues Research Articles

Cortical evidence for negative search templates

ABSTRACTA “target template”, specifying target features, is thought to benefit visual search performance. Setting up a “negative template”, specifying distractor features, should improve distractor inhibition and also benefit target detection. In the current fMRI study, subjects were required to search for a target among distractors enclosed in coloured circles. Before search, one of three colour cues appeared: a positive cue indicating the target will appear in the same colour, a negative cue indicating only distractors will appear in the same colour, or a neutral cue indicating that the same colour will not appear in the search display. fMRI results revealed down-regulation of neural processing in large parts of visual cortex following negative compared to positive cues. We further found a general attention inhibition mechanism in SPL/precuneus for neutral cues compared to positive and negative cues. These results suggest a cortical distinction between target templates, negative templates, and task-irrelevant distractor inhibition.

Salient object detection via color and texture cues

In this paper, we present a new bottom-up salient object detection approach by constructing two graphs using color and texture features within the manifold ranking framework. First, we calculate the saliency of boundary patches and exclude the ones with high saliency which might be a part of saliency object. Second, we adopt a two-stage scheme for salient detection via affinity propagation clustering and graph-based manifold ranking. The background-based saliency detection aims to obtain the salient object regions as much as possible. In the foreground-based saliency detection, a similar computation is processed as that in the former step and yet slightly different. Instead of simultaneously using all the extracted boundary patches or foreground patches as queries, we compute saliency by using the patches in each cluster in turn and integrating them. At last, the final saliency map is generated by linearly combining two saliency maps respectively exploring color and texture cues. Both qualitative and quantitative evaluations on three publicly available datasets demonstrate the robustness and efficiency of our proposed approach against 21 state-of-the-art methods.

Spectral segmentation via minimum barrier distance

Constructing a reliable affinity matrix is crucial for spectral segmentation. In this paper, we define a technique to create a reliable affinity matrix for the application to spectral segmentation. We propose an affinity model based on the minimum barrier distance (MBD). First, the image is over-segmented into superpixels; then the subset of the pixels, located in the center of these superpixels, is used to compute the MBD-based affinities of the original image, with particular care taken to avoid a strong boundary, as described in the classical model. To deal with images with faint object and random or “clutter” background, we present gradient data that are integrated with the MBD data. To capture different perceptual grouping cues, the completed affinity model includes MBD, color, and spatial cues of the image. Finally, spectral segmentation is implemented at the superpixel level to provide an image segmentation result with pixel granularity. Experiments using the Berkeley image segmentation database validate the effectiveness of the proposed method. Covering, PRI, VOI, and the F-measure are used to evaluate the results relative to several state-of-the-art algorithms.

Complex maze learning by fish

Rats, mice and other rodents are well-known for their ability to solve complex spatial tasks, such as learning to negotiate complicated mazes. This ability might be an adaptation for the fossorial habit that characterizes most rodents, but the scarcity of data from other taxa prevents us from confirming this hypothesis. We tested guppies, Poecilia reticulata, for their ability to navigate a maze consisting of six consecutive T-junctions. Guppies learned to solve the complex maze, and both the number of errors and the time to exit significantly decreased during the training period, which consisted of 30 trials over 5 test days. Guppies reached 68% correct responses on the first day of training and they exceeded 80% correct responses by the last day of training. We found no difference between a condition in which colour cues made each T-junction distinct from the others and a condition with no such cues. In contrast with the male advantage in spatial tasks previously observed in guppies, we found a small but significant female advantage in complex maze learning. Our work suggests that the ability to learn complex mazes is not a prerogative of those species that inhabit burrow systems such as mice and rats, but it might be common in vertebrates.

Compliance instead of flexibility? On age-related differences in cognitive control during visual search

The effect of healthy aging on cognitive control of irrelevant visual information was investigated by using event-related potentials. Participants performed a spatial cuing task where an irrelevant color cue that was either contingent (color search) or noncontingent (shape search) on the attentional set was presented before a target with different stimulus-onset asynchronies. In the contingent condition, attentional capture appeared independent of age and persisted over the stimulus-onset asynchronies but was markedly pronounced for elderly people. Accordingly, event-related potential analyses revealed that both older and younger adults initially selected the irrelevant cue when it was contingent on the attentional set and transferred spatial cue information into working memory. However, only younger adults revealed inhibitory mechanisms to compensate for attentional capture. It is proposed that this age-related lack of reactive inhibition leads to stickiness in visual processing whenever information is contingent on the attentional set, unveiling older adults' “Achilles' heel” in cognitive control.

Informative Cues Facilitate Saccadic Localization in Blindsight Monkeys.

Patients with damage to the primary visual cortex (V1) demonstrate residual visual performance during laboratory tasks despite denying having a conscious percept. The mechanisms behind such performance, often called blindsight, are not fully understood, but the use of surgically-induced unilateral V1 lesions in macaque monkeys provides a useful animal model for exploring such mechanisms. For example, V1-lesioned monkeys localize stimuli in a forced-choice condition while at the same time failing to report awareness of identical stimuli in a yes-no detection condition, similar to human patients. Moreover, residual cognitive processes, including saliency-guided eye movements, bottom-up attention with peripheral non-informative cues, and spatial short-term memory, have all been demonstrated in these animals. Here we examined whether post-lesion residual visuomotor processing can be modulated by top-down task knowledge. We tested two V1-lesioned monkeys with a visually guided saccade task in which we provided an informative foveal pre-cue about upcoming target location. Our monkeys fixated while we presented a leftward or rightward arrow (serving as a pre-cue) superimposed on the fixation point (FP). After various cue-target onset asynchronies (CTOAs), a saccadic target (of variable contrast across trials) was presented either in the affected (contra-lesional) or seeing (ipsi-lesional) hemifield. Critically, target location was in the same hemifield that the arrow pre-cue pointed towards in 80% of the trials (valid-cue trials), making the cue highly useful for task performance. In both monkeys, correct saccade reaction times were shorter during valid than invalid trials. Moreover, in one monkey, the ratio of correct saccades towards the affected hemifield was higher during valid than invalid trials. We replicated both reaction time and correct ratio effects in the same monkey using a symbolic color cue. These results suggest that V1-lesion monkeys can use informative cues to localize stimuli in the contra-lesional hemifield, consistent with reports of a human blindsight subject being able to direct attention in cueing paradigms. Because the superior colliculus (SC) may contribute to residual visual capabilities after V1 lesions, and because this structure is important for controlling attentional resources, we hypothesize that our results reflect, among others, SC involvement in integrating top-down task knowledge for guiding orienting behavior.

Research on Dynamic Targets Tracking Based on Color Cues Under Complicated Scene

Abstract Compared with DST, DSmT can be good evidence of contradictions to resolve the issue of evidence portfolios, In view of the occluding in tracking dynamic targets in complex background, a new anti-occluding target tracking algorithm based on DSmT and particle filter is proposed by color cues. The simulation results show that the proposed algorithm is effective and practicable in tracking occluded target and intersected target. Compared with the existing combination rules, the newly proposed rule is applied to both cases of conflicting and coincidence

Relative colour cues improve colour constancy in birds.

A ripe strawberry looks red to our eyes in sunlight and in the green light of a forest, although the spectrum of light reflected from its surface differs dramatically. This is caused by two effects: colour constancy and our ability to learn relative colour cues - the ripe strawberry remains relatively 'redder' than an unripe green strawberry. While colour constancy - the ability to recognize colours in shifted illumination - has been studied in many animals, the use of relative colour cues is investigated more rarely. In a previous study on chickens, we measured how large a shift in illumination their colour constancy mechanisms tolerate without reliable relative colour cues. Here, we show that chickens remain colour constant over larger illumination shifts, if they can use such relative colour cues. As relative colour cues are readily available in natural environments, we suggest that their use contributes strongly to colour constancy performance in nature.

Influence of Perceptual Saliency Hierarchy on Learning of Language Structures: An Artificial Language Learning Experiment.

Psychological experiments have revealed that in normal visual perception of humans, color cues are more salient than shape cues, which are more salient than textural patterns. We carried out an artificial language learning experiment to study whether such perceptual saliency hierarchy (color > shape > texture) influences the learning of orders regulating adjectives of involved visual features in a manner either congruent (expressing a salient feature in a salient part of the form) or incongruent (expressing a salient feature in a less salient part of the form) with that hierarchy. Results showed that within a few rounds of learning participants could learn the compositional segments encoding the visual features and the order between them, generalize the learned knowledge to unseen instances with the same or different orders, and show learning biases for orders that are congruent with the perceptual saliency hierarchy. Although the learning performances for both the biased and unbiased orders became similar given more learning trials, our study confirms that this type of individual perceptual constraint could contribute to the structural configuration of language, and points out that such constraint, as well as other factors, could collectively affect the structural diversity in languages.

Colour Cues That Are Not Directly Attached to the Body of Males Do Not Influence the Mate Choice of Zebra Finches.

Mate choice decisions of female zebra finches are generally thought to rely on the assessment of male quality, which includes the specific ornamentation of males. A commonly used paradigm to experimentally manipulate a male’s attractiveness is to add a coloured leg ring to the bird. Some studies have shown that female zebra finches prefer or alter their investment in males that have an additional red leg ring compared with males with green leg rings. Whether the coloured artificial ornaments need to be attached to the male’s body or whether environmental colouration could have a similar effect on male attractiveness remains unclear. Here, I investigated this novel context to determine whether female choice between males is affected by environmental colour cues that are not directly attached to the male’s body in four experiments involving 220 zebra finches (Taeniopygia guttata).A first experiment revealed that females chose males with red colour cues in the environmental background over males with green cues in the background. Based on this finding, I conducted follow-up experiments to obtain a deeper understanding of how environmental colour cues affect mate choice. Therefore, I examined whether female choice behaviour or male behaviour was altered in two additional experiments. Both experiments failed to show any effects of environmental colour cues on female choice or on male behaviour. Therefore, I replicated the initial experiment in a fourth experiment. Again replication failed; thus, the initial results indicating that environmental colouration affects mate choice behaviour of female zebra finches were not supported by the three subsequent experiments; thus, the outcome of the first experiment seems to be a false positive. Taking my results together, I found no robust support for the idea that environmental colour cues that are not directly attached to the body of male zebra finches affect female mate choice decisions.

Mean shift and log-polar transform for road sign detection

Road sign detection is an important function for driver assistance systems. Although it has been studied for many years, it still has some performance limitations. This paper proposes a new method for road sign detection by employing both color and shape cues. The proposed method consists of three steps. First, the initial image is pre-processed using mean shift clustering algorithm. The clustering is carried out based on color information. Second, a random forest classifier is used to segment the clustered image. In the final step, a shape based classification is performed using a log-polar transform and cross correlation technique. The proposed detection method has been tested on both the German traffic sign detection benchmark (GTSDB) and the Swedish traffic signs (STS) datasets, and yields to 93.50 % and 94.22 % on the GTSDB dataset in terms of F-measure and area under curve(AUC), respectively. These results are satisfactory when compared to recent state-of-the-art methods.

Graphics help patients distinguish between urgent and non-urgent deviations in laboratory test results

ABSTRACT Objective: Most electronic health record systems provide laboratory test results to patients in table format. We tested whether presenting such results in visual displays (number lines) could improve understanding. Materials and Methods: We presented 1620 adults recruited from a demographically diverse Internet panel with hypothetical results from several common laboratory tests, first showing near-normal results and then more extreme values. Participants viewed results in either table format (with a “standard range” provided) or one of 3 number line formats: a simple 2-color format, a format with diagnostic categories such as “borderline high” indicated by colored blocks, and a gradient format that used color gradients to smoothly represent increasing risk as values deviated from standard ranges. We measured respondents’ subjective sense of urgency about each test result, their behavioral intentions, and their perceptions of the display format. Results: Visual displays reduced respondents’ perceived urgency and desire to contact health care providers immediately for near-normal test results compared to tables but did not affect their perceptions of extreme values. In regression analyses controlling for respondent health literacy, numeracy, and graphical literacy, gradient line displays resulted in the greatest sensitivity to changes in test results. Discussion: Unlike tables, which only tell patients whether test results are normal or not, visual displays can increase the meaningfulness of test results by clearly defining possible values and leveraging color cues and evaluative labels. Conclusion: Patient-facing displays of laboratory test results should use visual displays rather than tables to increase people’s sensitivity to variations in their results.

Individual differences in personality in laying hens are related to learning a colour cue association

Personality can influence how animals perceive and learn cues. The behaviour and physiological responses animals show during stressful events is indicative of their personality. Acute induced stress prior to a cognitive test are known to affect the judgement of a stimulus, but personality of an individual could also affect learning of a specific cognitive paradigm. Here, we assessed if adult laying hens’ behaviour and physiological responses, as indicators of their personality, were related to their cognitive performance. We assessed their behavioural responses to a tonic immobility test, an open field test, and a manual restraint test, and measured plasma corticosterone levels after manual restraint. After that, hens (n=20) were trained in a pre-set training schedule to associate a colour-cue with a reward. In a two-choice go–go test, hens needed to choose between a baited or non-baited food container displayed randomly on the left or right side of an arena. Success in learning was related to personality, with better performance of hens which showed a reactive personality type by a long latency to walk, struggle or vocalize during the tests. Only eight out of 20 hens reached the training criteria. The non-learners showed a strong side preference during all training days. Side preferences were strong in hens with high levels of plasma corticosterone and with a long duration of tonic immobility, indicating that fearful, stress-sensitive hens are more prone to develop side biases. Our results show that learning can be hindered by side biases, and fearful animals with a more proactive personality type are more sensitive to develop such biases.

Egocentric-Vision based Hand Posture Control System for Reconnaissance Robots

To facilitate full-loaded commandos to control reconnaissance robots, in this paper, we propose a wearable hand posture control system based on egocentric-vision by imitating the sign language interaction way among commandos. Considering the characteristics of the egocentric-vision on the battlefield, such as complicated backgrounds, large ego-motions and extreme transitions in lighting, a new hand detector based on Binary Edge HOG Block (BEHB) features is proposed to extract articulated postures from the egocentric-vision. Different from many other methods that use skin color cues, our proposed hand detector adopts contour cues and part-based voting idea. This means that our algorithm can be used on the battlefield even in dark environment, because infrared cameras can be used to get contour images rather than skin color images. The experiment result shows that the proposed hand detector can get a better posture detection result on the NUS hand posture dataset II. To improve hand recognition accuracy, a deep ensemble hybrid classifier is proposed by combing hybrid CNN-SVM classifier and ensemble technique. Compared with other state-of-art algorithms, the proposed classifier yields a recognition accuracy of 97.72 % on the NUS hand posture dataset II. At last, to reduce misjudgments during consecutive posture switches, a vote filter is proposed and applied to the sequence of the recognition results. The scout experiment shows that our wearable hand posture control system is more suitable than traditional hand-held controllers for full-loaded commandos to control reconnaissance robots.

Striatal and Tegmental Neurons Code Critical Signals for Temporal-Difference Learning of State Value in Domestic Chicks.

To ensure survival, animals must update the internal representations of their environment in a trial-and-error fashion. Psychological studies of associative learning and neurophysiological analyses of dopaminergic neurons have suggested that this updating process involves the temporal-difference (TD) method in the basal ganglia network. However, the way in which the component variables of the TD method are implemented at the neuronal level is unclear. To investigate the underlying neural mechanisms, we trained domestic chicks to associate color cues with food rewards. We recorded neuronal activities from the medial striatum or tegmentum in a freely behaving condition and examined how reward omission changed neuronal firing. To compare neuronal activities with the signals assumed in the TD method, we simulated the behavioral task in the form of a finite sequence composed of discrete steps of time. The three signals assumed in the simulated task were the prediction signal, the target signal for updating, and the TD-error signal. In both the medial striatum and tegmentum, the majority of recorded neurons were categorized into three types according to their fitness for three models, though these neurons tended to form a continuum spectrum without distinct differences in the firing rate. Specifically, two types of striatal neurons successfully mimicked the target signal and the prediction signal. A linear summation of these two types of striatum neurons was a good fit for the activity of one type of tegmental neurons mimicking the TD-error signal. The present study thus demonstrates that the striatum and tegmentum can convey the signals critically required for the TD method. Based on the theoretical and neurophysiological studies, together with tract-tracing data, we propose a novel model to explain how the convergence of signals represented in the striatum could lead to the computation of TD error in tegmental dopaminergic neurons.

Role of human premotor dorsal region in learning a conditional visuomotor task.

Conditional learning involves stimulus identification, motor response selection, response monitoring, memory encoding, and recall of the learned association. Premotor dorsal (PMd) has been implicated for conditional learning. However, the extent to which PMd might be involved in specific or all stages of conditional learning is not well understood. The novel finding of our study is that PMd appears to be involved with monitoring motor responses, a sensorimotor integration stage essential for conditional learning.

The development and risk management features of a novel disinfectant

Introduction: A new disinfectant system has been developed in which the active species (peracetic acid) is generated in situ by dissolution in water. In order to provide a safer, more effective product for the end-user, several risk mitigation features have been built into the product, whilst meeting the requirements of the Australian regulatory framework for disinfectants under Therapeutic Goods Order 54, 1996 (TGO54). Methods: In order to provide an effective disinfectant system, a novel indicating system has been built into the formulation to provide a colour cue as to when an effective quantity of biocide has been produced. Also, by studying the concentration- time profile of the generation system, it was possible to define the in-use window of the generated disinfectant solution. This in turn allowed testing to define the antimicrobial efficacy of the disinfectant whilst following the requirements of TGO54. Additional testing was performed to define the materials compatibility of the disinfectant, allowing its use as both a low level instrument grade disinfectant, and a surface disinfectant. Results: The disinfectant solution has been shown to be effective against bacteria, fungi and spores, whilst also meeting the performance criteria defined by TGO54 for an instrument grade disinfectant. Conclusion: The development program undertaken to develop this disinfectant program has provided a unique broad-spectrum disinfectant with several layers of risk mitigation built into the system to minimise operator error during use. It is intended that this product will provide a viable, user friendly alternative disinfectant for use in outbreak situations.

Are physiological and behavioral immune responses negatively correlated? Evidence from hormone-linked differences in men's face preferences

Behaviors that minimize exposure to sources of pathogens can carry opportunity costs. Consequently, how individuals resolve the tradeoff between the benefits and costs of behavioral immune responses should be sensitive to the extent to which they are vulnerable to infectious diseases. However, although it is a strong prediction of this functional flexibility principle, there is little compelling evidence that individuals with stronger physiological immune responses show weaker behavioral immune responses. Here we show that men with the combination of high testosterone and low cortisol levels, a hormonal profile recently found to be associated with particularly strong physiological immune responses, show weaker preferences for color cues associated with carotenoid pigmentation. Since carotenoid cues are thought to index vulnerability to infectious illnesses, our results are consistent with the functional flexibility principle's prediction that individuals with stronger physiological immune responses show weaker behavioral immune responses.

Cue-target contingencies modulate voluntary orienting of spatial attention: dissociable effects for speed and accuracy.

Voluntary orienting of spatial attention is typically investigated by visually presented directional cues, which are called predictive when they indicate where the target is more likely to appear. In this study, we investigated the nature of the potential link between cue predictivity (the proportion of valid trials) and the strength of the resulting covert orienting of attention. Participants judged the orientation of a unilateral Gabor grating preceded by a centrally presented, non-directional, color cue, arbitrarily prompting a leftwards or rightwards shift of attention. Unknown to them, cue predictivity was manipulated across blocks, whereby the cue was only predictive for either the first or the second half of the experiment. Our results show that the cueing effects were strongly influenced by the change in predictivity. This influence differently emerged in response speed and accuracy. The speed difference between valid and invalid trials was significantly larger when cues were predictive, and the amplitude of this effect was modulated at the single trial level by the recent trial history. Complementary to these findings, accuracy revealed a robust effect of block history and also a different time-course compared with speed, as if it mainly mirrored voluntary processes. These findings, obtained with a new manipulation and using arbitrary non-directional cueing, demonstrate that cue-target contingencies strongly modulate the way attention is deployed in space.

Stereoscopic image recoloring

Image recoloring is the process of modification and adjustment of color appearance in images. Existing methods address the recoloring of a single image. We propose a method for recoloring stereoscopic images. Naively recoloring each image independently will require a pair of strokes in the source stereoscopic image pair. However, it is difficult to require consistent strokes on both the left and right views. We show how to extend a single image recoloring to work on stereoscopic images. Our method requires only a few user strokes on the left view and automatically transfers the corresponding strokes to the right view. Then a nonlocal color linear model optimization assumption is designed. Our nonlocal color linear model inherits the advantages of global and local color propagation methods. Our approach can propagate color cues in a global manner which can propagate color relatively far from the provided color constraints, while it provides the user with good local control. The experimental results show that the recolorized image pair is geometrically consistent with the original one.