Health, UK (Commonwealth Union) – The science of color perception begins with light. Light, which is a form of electromagnetic radiation, travels in waves of varying lengths. The wavelength of light determines its color. For instance, shorter wavelengths correspond to blue light, while longer wavelengths are perceived as red light. Our eyes contain specialized cells called photoreceptors that are responsible for detecting light.
A recent study led by the University College London (UCL) researchers has revealed distinctions in how the brains of healthy older adults perceive color in comparison to their younger counterparts.
Published in Scientific Reports, the research delved into the reactions of pupils in younger and older individuals to various aspects of color in their environment. The study involved 17 healthy young adults, averaging 27.7 years of age, and 20 healthy older adults, with an average age of 64.4.
Participants were placed in a blackout room and exposed to 26 different colors, each displayed for five seconds, while the researchers measured the diameter of their pupils. The study found that pupils constrict in response to changes in color lightness and chroma (colorfulness). The spectrum of colors presented included dark, muted, saturated, and light shades of magenta, blue, green, yellow, and red, along with two shades of orange and four greyscale colors.
Utilizing an exceptionally sensitive eye-tracking camera that recorded pupil diameter at a rate of 1000 times per second, the research team observed that the pupils of healthy older individuals exhibited reduced constriction in response to color chroma compared to their younger counterparts. This contrast was particularly pronounced for green and magenta hues.
Interestingly, both younger and older adults displayed similar responses when it came to the ‘lightness’ of a color shade.
This groundbreaking study marks the first instance of employing pupillometry to illustrate that as individuals age, their brains become less responsive to the intensity of colors in their surroundings.
The study’s findings align with prior behavioral research indicating that older adults perceive surface colors to be less vibrant than their younger counterparts.
Lead author, Dr Janneke van Leeuwen of the UCL Queen Square Institute of Neurology, says “This work brings into question the long-held belief among scientists that colour perception remains relatively constant across the lifespan, and suggests instead that colours slowly fade as we age. Our findings might also help explain why our colour preferences may alter as we age – and why at least some older people may prefer to dress in bold colours.”
The scientists posit that with advancing age, there is a reduction in the body’s responsiveness to color saturation levels in the primary visual cortex. This region of the brain is responsible for receiving, integrating, and processing visual information transmitted from the retinas.
Earlier studies have indicated a similar phenomenon in a rare dementia variant known as posterior cortical atrophy (PCA). In this condition, observable challenges and irregularities in color perception may stem from a notable decline in the brain’s sensitivity to particular color tones, which has green and magenta in particular, within the primary visual cortex and its associated networks.
The co-corresponding author, Professor Jason Warren of the UCL Queen Square Institute of Neurology, says “Our findings could have wide implications for how we adapt fashion, décor and other colour ‘spaces’ for older people, and potentially even for our understanding of diseases of the ageing brain, such as dementia. People with dementia can show changes in colour preferences and other symptoms relating to the visual brain – to interpret these correctly, we first need to gauge the effects of healthy ageing on colour perception. Further research is therefore needed to delineate the functional neuroanatomy of our findings, as higher cortical areas might also be involved.”
