LED’s ability to produce natural light sources influences the behaviour and perceptions of humans. 

As mentioned previously in another article LED lights contain a high Colour Rendering Index (CRI), which means objects within LED lit areas appear more natural in colour. But what wasn’t mentioned deserves its own space. After all, what is this CRI? How does it make colours appear more natural? And why do such colours seem more aesthetically pleasing to people?  
It might seem strange, but LEDs shape the way we ‘eat with our eyes’. The reason for this is that sight is one of the first sensory criteria we use to decide what food we eat. So the most luscious looking strawberries or the fattest tomatoes are the types of food we are first attracted to. A great way to generate this attraction is to display the food as ‘naturally’ as possible, by using LED light for example.  
CRI is the measure of LED light’s ability to show objects – in this case food – ‘naturally’ compared to a familiar reference source i.e. daylight or incandescent light. The CRI spectrum allows us to quantitatively measure the bulb’s score out of 100. It is calculated from the differences in the chromaticities of eight CIE standard colour samples (CIE 1995) when illuminated by a light source and by a reference illuminant of the same correlated colour temperature (CCT); the smaller the average difference in chromaticities, the higher the CRI. A CRI of 100 represents the maximum value. Lower CRI values indicate that some colours may appear unnatural when illuminated by the lamp. Incandescent lamps have a CRI above 95. Cool white fluorescent lamps have a CRI of 62, however fluorescent lamps containing rare-earth phosphors are available with CRI values of 80 and above. Basically, the higher the CRI the more natural the light. 
From the mid twentieth century, it was reasoned by scientists that it might be useful to categorise how different types of illumination affected the perceived colour of the objects on which their light fell. They felt that such a classification could help lighting engineers choose a type of lighting to suit a given application. Hence, the CRI was conceived.    
You are probably wondering how does this relate to me wanting to buy the reddest apple? The correlation can be found within the field of Colour Psychology, which is the study of hues as a determinant of human behaviour. Research in this field explores whether colour influences perceptions that are not obvious – such as how we taste food – or how colour can even enhance the placebo effect. Essentially, it is the study of the emotional and mental effects colours have in all facets of our lives. 
In fact, colour psychology research suggests your surroundings could be influencing your emotions and affecting your state of mind. Have you ever noticed that certain places are especially calming and relaxing for you? Or extremely irritating? It might be because the colours in those environments are playing a part in shaping your perception of them. Some have sought to apply this research for the greater good: in Glasgow and Japan blue coloured streetlights were installed within certain neighbourhoods in order to reduce the crime rate. Although, whether the crime rate was dropped due to blue lights has been left unproven.  
However, the major application of colour psychology is used for marketing and branding. Since colours are important in influencing the perception consumers have on goods and services, the CRI and LEDs become highly important to marketers. Colour has now become a major consideration to every company’s marketing strategy, much time is spent matching the colour of a brand’s logo to the personality of its goods and services. It is the reason why you will find colours such as pink associated with feminine products and brands as opposed to more traditional masculine products. It is not an exact science however: research demonstrates that warm colours encourage spontaneous purchases, despite cooler colours being more favourable to most people.
But back to our luscious strawberries and fat tomatoes; supermarkets are the masters of colour psychology. You probably have noticed, after entering the one-way entrance of your local supermarket, that the first thing you see is the produce department. The reason for this is the sensory impact of all those textures, scents and colours, which are meant to make us feel hungry and cheerful.  
The supermarket’s sensory bombardment does not stop at the produce department either. On average a supermarket carries around 44,000 different items, bigger locations carrying thousands more. This volume of choice is enough to send people into a state of overload. According to new research, the demands brought on by so much decision-making overcome us by about 40 minutes into shopping. At this point we stop struggling to be rationally selective with our shopping, and instead, succumb to shopping through our emotions – and colour is the realm of emotion.
Aesthetic aspects of a product’s packaging, such as its brightness, typography and colour for example, influence where our eyes will land on the supermarket shelf. Thus, visually appealing products on the shelf attract consumers’ eyes and increase the attention we spend on these products. 
A prime example of how colour influences our consumer behaviour can be found in with the humble banana. The banana’s signature ripe yellow colouration that we love is actually the result of market analyses. Sales records show that bananas with Pantone colour 13-0858 (also known as Vibrant Yellow) are less likely to sell than bananas with Pantone colour 12-0752 (otherwise called Buttercup), which is visually one grade warmer, and seems to imply a fresher, riper fruit. Banana farmers reacted to this by planting their bananas under conditions tailored to produce the Buttercup colouration. That is why our bananas are coloured the way they are. 
Hence, it is no surprise that more and more attention is being focused on differing degrees of light. As technology improves and LEDs continue to reach the pinnacle of the CRI spectrum, new approaches to human behaviour and perception will also be studied. Whether future research will be investigating the perfect looking tomato, or analysing the blue lit crime-free streets of Glasgow, connections to light and colour will be inevitably linked to how we perceive the world.