I think that I notice that colours become brighter when I am feeling more cheerful than when I am feeling miserable. Of course, we do all have a certain amount of psychoactive brain chemicals naturally than without recourse to hallucinogenics.

One thing which I found strange was that I was using hallucinogenics on a regular basis was that I used to see hues of pastel shades of colour and coloured shadows, and some auras. I used to also see reflections in non reflective surfaces.

But, I think that some people are more trippy than others. I almost always saw visual images when I used to smoke dope. I used to see cathedral ceilings and images like in Hindu art. I wanted to sketch them, but the only thing substances which I felt able to use and draw the images I was seeing while using it was morning glory seeds. But, I don't recommend it because it gave me bad stomach ache because the seed manufacturers coat them poison to deter people from using them for this purposes.

Apart from colours, another interesting aspect of psychedelia is synthesaesia. I have a few instances of that without any substances, in which I found that sounds triggered visual images when my eyes were closed. Apparently, the reason why some people experience this is because the eyes and the ears develop from the same nodule.

Thanks for relating your personal experience with psychedelics. My point is, if color intensification is part of a trip, why not color perception itself?

A small clarification is in order. One of John Stuart Mill's many contributions to science is setting down a basic rule-set to for causal argumentation known as Mill's Methods. One of the rules is concomitant variation which basically states that if as some A increases/decreases, some B also increases/decreases proportionately, A causes B. In the case of pscyhedelics, increasing the level of psychedelic drugs in your blood stream intensifies color perception. Ergo, my argument is, color perception itself is caused by psychedelics.

We all see the world in technicolor even when not taking psychedelics. Could it be then that we're all tripping?

I think that it partly depends how you think about the nature of psychedelic reality, and I understand the word to be about mind expansion. I think that your idea that we are all tripping through seeing colours probably points to the way in which we take such vision for granted. I don't really because I do have some underlying vision problems, and my biggest fear is of going blind oneday. So, I try to be grateful for the amazing nature of vision, including the spectrum of colours.

I think that it comes down to the way in which we experience and think about perception and this is linked to art as a way of exploration. For most of my life I used to draw regularly and paint on occasions. However, I have barely done this at all for the last couple of years, partly due to being in the right state of mind and not having the right place to do it. I am aware that this may have had a negative impact on my appreciate of life and even contributed to my eyesight becoming blurry recently. I think visual perception and its appreciation is somehow central to our existence and brain functioning because the retina is part of the brain ultimately.

Going back to your way of thinking about colour there is the dichotomy about making art in black and white or in colour. Often I draw in black and white, but I do experiment in colours and find using a vast array of watercolour pencils is one way of doing this with a view to capturing the full colour spectrum. At one point in the past, people photography was usually done in black and white, and television was in that way, whereas we expect to view coloured pictures most of the time. But, it is an aspect of mind expanding perception really, or the perception of multidimensional reality.

Bad Bugs Bunny yuks aside, carrots are a rich source of beta-carotene, an antioxidant carotenoid that your body converts to vitamin A, which is essential for good vision. Vitamin A helps with the production of both rod and cone cells in the eyes, which help you see in low light conditions and see colors. — Random webpage

We had better remember to eat our carrots and, at least they are cheaper than psychedelics, and legal too.