Sharp-cornered objects caused much greater amygdala activation than rounded objects. A well-studied region in the temporal lobe of the brain, the amygdala’s primary function is to process stimuli that induce fear, anxiety, and aggressiveness and to deal with the resulting emotional reactions. In other words, angular shapes tend to trigger fear and therefore aversion and dislike. Moreover, the authors of the study noted that “the degree of amygdala activation was proportional to the degree of angularity or sharpness of the object presented, and inversely related to object preference”.

Lima, M. (2017)

The chroma level has an effect on activity (Miyamoto, 2003). The brighter the colour, the more a sense of dynamism will emerge (Valdez & Mehrabian, 1994). The psychologists da Pos and Green-Armytage (2007) obtained the same result in their research into colours and basic emotions. Passive feelings such as sadness and fear are associated with very unsaturated monochrome colours, while active feelings such as happiness, surprise and anger are linked to bright and very contrasting colours.

Mehrabian (1987; 1991) developed eight basic temperaments and their variations, defined in the PAD-model (Pleasure, Arousal, Dominance).
exuberant +P+A+D vs. bored -P-A-D
dependent +P+A-D vs. disdainful -P-A+D
relaxed +P-A+D vs. anxious -P+A-D
docile +P-A-D vs. hostile – P+A+D

• Exuberant= + Pleasure, + Arousal, + Dominance. Related emotions are extrovert, outgoing, happy, social.
• Bored = – Pleasure, – Arousal, – Dominance. Related emotions are sad, lonely, socially withdrawn, physically inactive.
• Dependent = + Pleasure, + Arousal, – Dominance. Related emotions are attached to people, helpless, interpersonal positive and social.
• Disdainful = – Pleasure, – Arousal, + Dominance. Related emotions are jealous, loner, withdrawn and calculated, sometimes anti-social.
• Relaxed = + Pleasure, – Arousal, + Dominance. Related emotions are comfortable, confident, self-assured, able to withstand stress.
• Anxious = – Pleasure, + Arousal, – Dominance. Related emotions are worried, nervous, insecure, tense, unhappy, easily sick.
• Docile = + Pleasure, – Arousal, – Dominance. Related emotions are pleasant, unemotional, indulgent, kind, behave appropriately.
• Hostile = – Pleasure, + Arousal, + Dominance. Related emotions are angry, negative emotional, possibly violent.

Harm Avoidance involves a heritable bias in the inhibition of behaviour in response to signals of punishment and frustrative non-reward. The trait is related to neuroticism.

People low in Harm Avoidance are carefree, courageous, energetic, outgoing and optimistic even in situations that worry most people.

High Harm Avoidance: Anticipatory worry, excessive worrying, pessimism, Shyness with strangers, shyness, Fear of uncertainty, Fatigability and asthenia, being fearful, doubtful, easily fatigued. It is observed as pessimistic worry in anticipation of problems, fear of uncertainty, shyness with strangers, and rapid fatigability. People high in Harm Avoidance are fearful, socially inhibited, shy, passive, easily tired, and pessimistic even in situations that do not worry other people.
(Cloninger, 1994)

The association of purple with strong internalization of affect, anxiety and tension seems supported by findings of elevated purple in a number of psychopathological groups.
Schaie, K. W., 1966

(Inez Michiels, 2022)