Visual Perception of Colour, Light and other Visual Properties
We are The Sussex Colour Group, a Research Lab based at the University of Sussex in the UK. We investigate human perception of colour, light and other visual properties. We are particularly focused on understanding the development of visual perception, as well as the perceptual and neural mechanisms that underpin visual perception in adults. We use a range of methods in our research, inlcuding infant and child testing, psychophysics, cross-cultural fieldwork, altered-reality and neuroimaging. Our research has been generously supported by funding from the European Research Council, UKRI and from a number of industrial partnerships and consultancies.
The Development of Visual Perception
We investigate how infants and children see, think and learn about colour and other visual properties, and the process by which visual perception develops. This gives us insight into children’s perceptual and cognitive development, and into infants and chidlren's' response to the world around them. Understanding how visual perception develops also gives insight into how it works in its mature form. Our infant studies are conducted in the Sussex Baby Lab (which is co-led by Anna Franklin & Alice Skelton): https://www.sussex.ac.uk/babylab/
Colour & Light: We have shown that infants have a remarkably rich visual experience of colour, can perceive its dimensions, and can categorise it using the sensory mechanisms of colour vision. Our studies reveal that infants have visual preferences for some colours over others, which strikingly resemble adults’ colour preferences. We also find that infants’ sensitivity to colour relates to the statistical regularities of colour and light in the natural environment, and that young children are able to keep colour perceptually constant despite changes in illumination. This perceptual constancy also relates to how well children can name colours. Working with older children, we have found that the presence of red has a slight effect on children’s performance on cognitive tasks in some contexts. We have also investigated colour and luminance discrimination in autistic children. We have applied our findings on the development of colour perception to develop a gamified psychophysical iPad app, called ColourSpot, which diagnoses colour vision deficiency (colour blindness) in children as young as 4. Current research is investigating the role of light and lighting in visual development. Current collaborations include Dana Turner's investigation of the ratio of L and M cones in infancy as part of Project COLOURCODE (led by Jenny Bosten). Researchers: Anna Franklin, Alice Skelton, Marie Rogers, Christoph Witzel, Jenny Bosten, Dana Turner. Funding: Economic Social Research Council, ERC Projects CATEGORIES, COLOURMIND & COLOURTEST, AkzoNobel.
Natural Scene & Image Statistics: Following on from our finding that infants' sensitivity to colour relates to the statistical regularities of colour and light in natural scenes, we have conducted a series of studies investigating infants' perception of a range of other scene and image statistics. We have found that a range of chromatic and spatial statistics, such as fractal dimension and edge orientation entropy, predict how long infants look at art, natural scenes, building facades, book images and abstract patterns. This gives insight into the statistical regularities that the immature infant visual system is capable of processing. We have also generated a dataset of 200K images from colour and spatially calibrated head-mounted cameras worn by infants and caregivers as they went about daily life. Our analysis of these egocentric scenes identifies differences in the 'visual diet' of infants and caregivers that give insight into the role of experience in visual development. Researchers: Anna Franklin, Alice Skelton, Jenny Bosten, Philip McAdams, Taysa-Ja Newman, Kath Symons, Richard Taylor, Megan Chambers, Charlotte Samuels. Funding: ERC Project COLOURMIND.
Aesthetics & Design: Little is known about how visual aesthetics develops. We are investigating how early sensory biases provide a foundation for the development of aesthetic experiences. So far, we find relationships between infant looking and adult aesthetic judgements for some stimuli (e.g., colour, van Gogh landscapes, building facades) but not others (e.g., natural scenes, book images). These findings inform our understanding of the sensory component of aesthetics. We have also been working with companies and organisations who design for, or work with infants and young children, weaving the methods and findings of our science into the design of early years books, products, theatre performance, and art gallery and museum provision. Researchers: Anna Franklin, Alice Skelton, Philip McAdams, Taysa-Ja Newman, Kath Symons, Anna Spencer, Charlotte Samuels. Funding: Etta Loves Ltd., Arts & Humanties Research Council and Economic and Social Research Council Impact Acceleration Funds.
Perceptual & Neural Mechanisms of Visual Perception
We want to understand what is ‘under the hood’ of human visual perception – to understand what perceptual processes enable us to perceive, think, like and talk about visual properties, and how those perceptual processes work. We also ask questions about the role of environment, culture and experience in visual perception. This enables us to contribute to broader debate in the cognitive sciences on topics such as the efficient coding of our visual system, the relativity of perception, and the principles of aesthetics.
Colour Categorisation: In addition to providing converging evidence that infants categorise colour, our European Research Council funded CATEGORIES project investigated the perceptual and neural mechanisms that underpin adult colour categorisation. We used ERPs to find a neural marker for the unique hues, and to clarify the time course of the effect of colour terms on perceptual and post-perceptual processes. Our fMRI study of colour categorisation also identified that the middle frontal gyrus encodes colour categorically whilst the visual cortex codes the perceptual similarity of colour. Researchers: Anna Franklin, Alice Skelton, John Maule, Lewis Forder, Xun He, Chris Bird. Funding: ERC Project CATEGORIES.
Visual Preference & Discomfort: We have provided support for the theory that colour preference relates to the valence of associated objects, and with cross-cultural work with the Himba, we have also refuted the theory that colour preferences are universal. Further cross-cultural research has identified a relationship between adults' visual preference and discomfort and their 'visual diet'. Using fMRI we have shown that the posterior midline cortex (precuneus, posterior cingulate and cuneus) are modulated by colour preference even when colours are passively viewed. This finding provides further evidence of the role of the default mode network in aesthetic preference. Current projects are investigating neurodiversity and visual preference & discomfort, in response to colour, light and lighting, using participatory methods. Researchers: Anna Franklin, Chloe Taylor, John Maule, Chris Racey, Zhe Gong & a Daylight Academy funded network on light and neurodiversity led by Paul Kenny.
Environmental Calibration: As part of project COLOURMIND, funded by the European Research Council, we have investigated how visual perception calibrates to the statistical regularities of natural scenes on multiple timescales. In one cross-cultural study (with Asifa Majid & Simeon Floyd), we measured the visual perception of people living in remote Esmeraldas rainforest, Quito city and Sussex using psychophysical tasks, and quantified people's visual diet using calibrated head-moutned cameras. We found relationships between sensitivity to visual stimuli and visual diet: for example, group differences in sensitivity to hue were consistent with perceptual learning in local environments. A COLOURMIND study conducted in Norway (with Bruno Laeng & Mikolaj Henik) has also found effects of season and latitude on a range of aspects of colour perception, and has related these effects to differences in visual diet measured using calibrated head-mounted cameras, spectroradiometers and hyperspectral imaging. We have also probed the limits of adaptation to chromatic scene statistics in a series of psychophysical experiements in the lab, and a study using Altered-Reality suggests that the visual system cannot adapt to a hue-rotated world. Our analyses of the 7T fMRI Natural Scene Dataset have also enabled us to further identify colour-biased regions of the brain using stimuli where colour is embodied in real-world scenes as in daily life, revealing correspondences between food and colour in ventral visual pathway. Researchers: Anna Franklin, Jenny Bosten, Alice Skelton, John Maule, Ian Pennock, Alex Swartz, Yesesvi Konakanchi, Beata Wozniak
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