Autumn brings a chilly shift in the air, the clunk of acorns falling on car roofs, the autumnal equinox, and the availability of pumpkin spice everything. However, autumn is primarily associated with leaves changing color, which is a plant’s physiological response to the decreased amount of sunlight and the need to reserve food stores. As trees transition from a monochromatic green to a patchwork of greens, reds, yellows, and browns, humans unconsciously have an emotional and physiological response simply because we are exposed to the colorful leaves. We react to autumn because not only are the leaves are aesthetically pleasing, but because we are hardwired to react.
In autumn we see colors ranging from the deep scarlet of red maples to the yellow-tinted maroon of sweetgums and the pale golden tone of sycamores. Leaf colors are caused by chlorophyll, carotenes, and xanthophylls—all of which are pigments that capture light energy used to create food via photosynthesis.
As summer transitions into winter, days grow shorter and the amount of sunlight decreases. During this time trees lower their production of chlorophyll, the green pigment that plays a major role in photosynthesis. All pigments are drawn back into the tree trunk to help the tree survive winter, however, chlorophyll is the first to go leaving (no pun intended) the carotenes and xanthophylls responsible for the oranges, purples, and reds we see.
Studies in color psychology indicate that each of these colors elicits an emotional response when we are exposed to them. In modern research, psychologists have evaluated moods, color preference, and physiological reactions to color (hue, brightness, and saturation) using surveys, galvanic skin response (GSR) tests, and electroencephalograms (EEGs). While there is some variation as a result of different methodologies, overall the following emotions have been associated with autumn colors:
Red: excitement, happiness, anger, arousal
Yellow: happiness, motivation, positivity
Orange*: warmth, happiness, comfort
Brown: stability, melancholy/pensiveness, strength
Magenta**: happiness, strength, sophistication;
whereas, green has been associated with safety, happiness, and calm.
*Denoted as “yellow-red” in many research articles
**Denoted as “red-purple” in many research articles
In addition to bringing about an elevated mood, exposure to red, yellow, and orange increases heart rate and increases the state of stimulation. During autumn the scenery changes from a constant soothing green to an array of simultaneously arousing and grounding colors that generate an assortment of emotions and moods, resulting in a dramatic response to the very visual season.
Johann Wolfgang von Goethe and Friedrich Schiller’s Rose of Temperaments (dated 1798) is the most well-known early evidence of mood-color association. With it, the two artists used a color wheel to create four categories of persona based on color schemes. The melancholic are the philosophers and are associated with red, purple, and magenta. The sanguine are the lovers and poets, and are associated with green, yellow, and blue. Choleric, the heroes and adventurers, are ascribed yellow, red, and orange. And the phlegmatic are the historians, teachers, and public speakers associated with blues and purple. Given that reds, oranges, yellows are more stimulating than blues and greens, it is no wonder that the warmer colors are used to denote heroes and individuals who thrive in adrenaline-inducing situations.