Chromatic Preference Research Articles

Visuo-motor lateralization in Apis mellifera: flight speed differences in foraging choices

Evidence of lateralization has been provided in Apis mellifera in olfactory learning and social interactions, but not much is known about how it influences visuo-motor tasks. This study investigates visuo-motor biases in free-flying honeybees by analysing left/right choices related to foraging in a Y-maze. Individual bees were trained to associate a visual stimulus (a blue or yellow target) with a reward/punishment: the Blue + group was reinforced for the blue and punished for the yellow, and vice versa for the Yellow + group. In unrewarded tests, we assessed for each bee the directional choice for one of the two identical targets (12 trials with blue targets and 12 with yellow targets) placed in the left and right arms of the maze as well as the flight times to reach the target chosen. The results did not reveal a significant directional preference at the population level, but only at the individual level, with some individuals presenting a strong bias for choosing the right or left stimulus. However, the data revealed an interesting new factor: the influence of both direction and colour on flight times. Overall, bees took less time to choose the stimulus in the left arm. Furthermore, the yellow target, when previously associated with a punishment, was reached on average faster than the punished blue target, with a higher number of no-choices for punished blue targets than for punished yellow targets. This opens new perspectives not only on the study of lateralization in Apis mellifera, but also on the bees’ chromatic preferences.

Chromatic preferences in group of hues through fashion products in the Seridó region of Rio Grande do Norte, Brazil

Color is the observer's first contact with the surface of objects and most people with the world. As natural to human experience, there is a tendency to prefer certain objects, elements, or artifacts over others; Knowing the means of manipulating these color preferences is therefore important to ensure effectiveness and acceptance in product development. The present work aimed to map and describe the color preferences through the groups of the color hue of the inhabitants of Caico, in the state of Rio Grande do Norte, Brazil, when they are related to fashion products. Being classified as a field research - survey, exploratory-descriptive objective, and quantitative-qualitative approach. The questionnaire was conducted during the VI EXPOTEC of IFRN/Caico with a sample of 170 individuals, comprising 117 females and 53 males, with ages ranging from 7 to 64 years. As a result, there was a predominant targeting of pink and violet hues, in general, and specifically in 3 of the 5 areas of the city, as well as a great refusal to the greenish hues identified in all regions of the city.

Chromatic Preferences for Industrially-Manufactured Products

Several researches were focused on identifying the chromatic preference in general and on detecting the differences between women and men regarding the colour choices. Usually, researches are carried-out in a theoretical framework, considering that the preferred colours are invariant to their support. The experiment presented in this paper studied the chromatic preference considering three cases: neutral case (colours per se), low-tech products (colours on mugs) and high-tech products (colours on Lytro cameras). Also, the research studied the chromatic preference in terms of types of colours (focal, light, dark and intermediate).

Local Signals in Mouse Horizontal Cell Dendrites

The mouse retina contains a single type of horizontal cell, a GABAergic interneuron that samples from all cone photoreceptors within reach and modulates their glutamatergic output via parallel feedback mechanisms. Because horizontal cells form an electrically coupled network, they have been implicated in global signal processing, such as large-scale contrast enhancement. Recently, it has been proposed that horizontal cells can also act locally at the level of individual cone photoreceptors. To test this possibility physiologically, we used two-photon microscopy to record light stimulus-evoked Ca2+ signals in cone axon terminals and horizontal cell dendrites as well as glutamate release in the outer plexiform layer. By selectively stimulating the two mouse cone opsins with green and UV light, we assessed whether signals from individual cones remain isolated within horizontal cell dendritic tips or whether they spread across the dendritic arbor. Consistent with the mouse's opsin expression gradient, we found that the Ca2+ signals recorded from dendrites of dorsal horizontal cells were dominated by M-opsin and those of ventral horizontal cells by S-opsin activation. The signals measured in neighboring horizontal cell dendritic tips varied markedly in their chromatic preference, arguing against global processing. Rather, our experimental data and results from biophysically realistic modeling support the idea that horizontal cells can process cone input locally, extending the classical view of horizontal cell function. Pharmacologically removing horizontal cells from the circuitry reduced the sensitivity of the cone signal to low frequencies, suggesting that local horizontal cell feedback shapes the temporal properties of cone output.

Local signal processing in mouse horizontal cell dendrites

The mouse retina contains a single type of horizontal cell, a GABAergic interneuron that samples from all cone photoreceptors within reach and modulates their glutamatergic output via parallel feedback mechanisms. Because horizontal cells form an electrically-coupled network, they have been implicated in global signal processing, such as large scale contrast enhancement. Recently, it has been proposed that horizontal cells can also act locally at the level of individual cone photoreceptor axon terminals. To test this possibility physiologically, we used two-photon microscopy to record light-evoked Ca2+ signals in cone axon terminals and horizontal cell dendrites as well as glutamate release in the outer plexiform layer. By selectively stimulating the two mouse cone opsins with green and UV light, we assessed whether signals from individual cones remain “isolated” within horizontal cell dendritic tips, or whether they spread across the dendritic arbour. Consistent with the mouse9s opsin expression gradient, we found that light responses recorded from dendrites of dorsal horizontal cells were dominated by M- and those of ventral horizontal cells by S-opsin activation. Light responses measured in neighbouring horizontal cell dendritic tips varied markedly in their chromatic preference, arguing against global processing. Rather, our data support the idea that horizontal cells can process cone input locally, extending the “classical” view of horizontal cells function. Pharmacologically removing horizontal cells from the circuitry reduced the sensitivity of the cone signal to low frequencies, suggesting that local horizontal cell feedback shapes the temporal properties of cone output.

Background chromatic contrast preference in cases with age-related macular degeneration

ObjectiveTo identify background chromatic contrast preferred subjectively by patients with age-related macular degeneration (AMD). MethodsProspective observational case series. Study subjects with AMD were recruited and compared to a control group of study subjects with normal vision. Study subjects were presented with letter size printed sheets of white paper with randomly typed 2M size standard black optotypes. Chromatic contrast was created with colored plastic sheets positioned on top of the black on white printed sheets. The 4 major color hues which were selected for testing were blue, yellow, green and red. Study subjects were required to identify background contrast best preferred for viewing at the end of 4 trial sequences. Results40 subjects with AMD were recruited together with 57 study subjects with normal vision. In either the control group or the group with AMD subjects the majority's chromatic preference for background was yellow (56.14%, p=0.42 and 71.67%, p=0.006 respectively) with subjects with AMD preferring yellow color background significantly more than subjects with normal vision (p=0.0002). ConclusionsYellow color background seems to be preferred by most of healthy and AMD eyes. This preference may be modulated by factors such as the yellow-blue vision processing channel and/or luminosity differences produced by selectively transmitted light.

Modeling self-organizing tri-chromatic color selective regions in primary visual cortex

How does the brain represent and process color in the primary visual cortex (V1)? Experimental evidence from macaque monkey suggests that cells selective for color are organized into small, spatially separated blobs in V1. This organization is strikingly different from that of orientation and ocular dominance maps, which consist of large, spatially contiguous patterns. In this paper, a self-organizing tri-chromatic model of V1 is constructed using natural color image input. Neurons in the modeled V1 are initially unselective, and develop multi-lobed ON/OFF receptive fields through Hebbian learning of retinal responses to visual patterns. The model develops realistic color-selective receptive fields, color maps, ocular dominance columns, and orientation maps. Color-selective blobs are located inside ocular dominance columns, and lateral connections link cells with similar orientation preferences, matching previous experimental results. Further, the model makes a number of predictions for future experiments, including: 1. The color map has three types of color-selective blobs and a unique cortical activation pattern exists for each of the pure color hues. 2. The usual blob-like organization for color emerges as long as the training images have a higher brightness contour gradient compared to the hue contour gradient, and the inputs are highly correlated between the eyes. Otherwise the color blobs regularly extend across borders of ocular dominance stripes (contrary to macaque results). 3. Neurons in areas where red and green patches are near each other respond to both red and green, causing them to maximally prefer yellow, even though there are no yellow photoreceptors in the retina. 4. Cells selective for color connect to other cells with similar chromatic preferences: Blue-selective neurons connect to blue selective neurons, red-selective to other red-selective neurons, and so forth. Thus the model replicates the known data on the organization of color selectivity in V1, gives a detailed explanation for how this structure develops and functions, and provides concrete predictions that can be tested in future experiments. These findings suggest that a single self-organizing system may underlie the development of orientation selectivity, eye preference, color selectivity, and lateral connectivity in the primary visual cortex.

Self-organization of color opponent receptive fields and laterally connected orientation maps

Long-range lateral connections in the primary visual cortex (V1) are known to link neurons with similar orientation preferences, but it is not yet known how color-selective cells are connected. Using a self-organizing model of V1 with natural color image input, we show that realistic color-selective receptive fields, color maps, and orientation maps develop. Connections between orientation-selective cells match previous experimental results, and the model predicts that color-selective cells will primarily connect to other cells with similar chromatic preferences. These findings suggest that a single self-organizing system may underlie the development of orientation selectivity, color selectivity, and lateral connectivity.

The Selectivity of Motion-Driven Visual Attention in Infants

The onset of motion was used to study stimulus-driven visual attention in 14-week-olds. The movement of an object did not capture attention reflexively at 14 weeks of age. The attention-getting properties of a moving stimulus depended significantly on its color in combination with the colors of other objects in the visual field. Specifically, detection of a green moving target was masked in the presence of mixed red and green static objects. No such masking was observed when the moving target was red or when the green target moved in a visual field that was populated only with green objects. The same effect was observed to a lesser extent when the green bars were replaced with gray bars. The number of distractors in the visual field exerted an effect on the accuracy of detection only when their appearance in the visual field was coincident with the onset of target motion. Attention to motion at this age is not independent of the structure of the visual field; chromatic preferences play a role in how readily infants attend to a moving object. These effects may be mediated by a difficulty in disengaging attention (from distractors) or in suppressing attention to competing objects once attention is engaged on a target.

Aspects of spectral sensitivity inTalitrus saltator(Montagu) (Crustacea‐Amphipoda)

Spectral sensitivity in Talitrus saltator (Montagu, 1808) was investigated with classical electroretinographic techniques and behaviourally with a choice experiment. Both tests demonstrated a high sensitivity for blue light of wavelength around 450 nm, the main component of solar illumination over the sea. This maximum sensitivity could be used to guide T. saltator towards the sea to keep it within its preferred habitat on the wet zone of the beach. Colour discrimination capability was investigated by comparing the electroretinograms obtained in different conditions of adaptation (dark, blue and yellow light) and the behavioural responses to lights of different colour and varying intensities. The results of these tests suggest that, besides higher sensitivity, a specific chromatic preference for blue light could also improve seawards orientation. In its general features, the vision of T. saltator appears to be adapted for a sub‐aerial style of life on the seashore.