Fear is the deepest emotion one can ever feel. It has many implicit effects on our mind, affecting all aspects of our thinking. Thus, fear should be seriously stressed in virtually any attempt to analyze human behavior, especially in such a context that the overall living pressure skyrocketed recently.

In this article, several proposed origins of fear will be discussed and analyzed. We hope this short review can be of good use.

Introduction to Fear

According to some sources, fear is an emotion induced by a threat imposed by the outside world or by the subject itself(Merriam-Webster, 2014). This definition is definitely correct, though it has little description on the nature of fear. To better understand fear, we have to first throw our intuitive impressions on fear away, which leads us to reconsider the definition of the very word “fear”. This is a phenomenological approach(Yamane, 2007).

Origins of Fear

The origin of fear remains a mystery even in the 21th century. In the ancient times, fear and other emotions are usually attributed to the intrinsic nature of human souls, in an idealistic way. As epistemology develops, modern psychologists usually consider fear in evolutional or neurophysiological aspects(LEDOUX, 2012).

The evolutional recognition of fear is most appreciated by the community. This approach states that the existence of fear is necessary in the early development of species. For example, the fight-or-flight response, which is important in the survival of an animal(Porges, 1997). Some other theories (Toda, 2007) proposes that fear and other emotions is purely mechanical, like complex computers.

Meanwhile, some oppositions have been issued by some scientists, which point out that this pure evolutional view lacks recognition for the subjective perception of threats and fear mentally by human beings(Yamane, 2007). Moreover, pure evolutional theories fails to explain the human intuition on potential danger, as intuition obviously involves the top-level functioning of the brain.

Sometimes the word “panic” is used as an synonym of “fear”, which is erroneous for panic is actually a subtype of fear, as is explained in (APA, 2000).


Though multiple researches have been successful in proving the existence of fear-inducing hormones (Corticosterones, etc.), we still argue that the metal perspective of fear should never be overlooked.As stated in (Toda, 2007) and (Hebb, 1946), fear is connected with high-level brain functioning. Fear can be artificially created by imposing a relationship between certain events with danger (fear conditioning)(Maren, 2001). This is proved by the famous Little Albert experiment(Watson & Rayner, 1920).

All views have their own limitations. Fear, as an emotion, is definitely related with our deep thoughts. Still, from an evolutionary viewpoint, some types of fear are induced by hormonal stimulations, which is a signature of the origin of human beings.Thus a new theory has to be established, which I propose as “Mixed Automaton Theory”.

Mixed Automaton Theory

The Mixed Machine Theory recognizes fear as an “Exception Handling” mechanism. In analogue with the exception handling mechanism in computer systems, we first consider the brain as a probabilistic automaton, which is defined as an automaton where state switching is controlled in a probabilistic manner(Rabin, 1963).

As in its definition, an automaton can only have a set of predefined states in normal conditions. But in real-world situations, an automaton can be put into a state that is not in the set, which is called an illegal state. In this state, the automaton will either a) switch to a random state or b) send an alarm signal and fallback to an error handling state.

The brain does the same when encountering off-limit situations. Fear is here considered the exception processing routine, which tries to solve the problematic situation and restore the brain to a legal state.

Another pathway for fear induction, namely the hormonal pathway, can also be regarded as a supplement to the brain automata as hormones can keep the response sustained, as neurological reactions usually does not.

This mechanism can explain the problems stated in (Yamane, 2007) and (LEDOUX, 2012).


The integrity of this theory remains to be reviewed, but we hope that this theory can lead to a unified theory which can explain all types of emotions, like the Grand Unified Theory in physics.

Further research may follow as this theory needs clarification.

I am honored to work with my group members, their excellent performance will never be forgotten.

Many thanks for my psychology teacher, Zhifeng Sun in guiding me to reconcile my knowledge of psychology.

Thank you for reading this article.


APA, A. P. A. (2000). DSM-IV-TR: Diagnostic and statistical manual of mental disorders, text revision: American Psychiatric Association.

Hebb, D. O. (1946). On the nature of fear. Psychological Review, 53(5), 259.

LEDOUX, J. (2012). Searching the Brain for the Roots of Fear. OPINIONATOR. 2014, from http://opinionator.blogs.nytimes.com/2012/01/22/anatomy-of-fear/?_php=true&_type=blogs&_r=0

Maren, S. (2001). Neurobiology of Pavlovian fear conditioning. Annual review of neuroscience, 24(1), 897-931.

Merriam-Webster. (2014). The Merriam-Webster Online Dictionary: Fear.Retrieved 2014/6/29, 2014, from http://www.merriam-webster.com/medical/fear

Porges, S. W. (1997). Emotion: An Evolutionary By-Product of the Neural Regulation of the Autonomic Nervous Systema. Annals of the New York Academy of Sciences, 807(1), 62-77.

Rabin, M. O. (1963). Probabilistic automata. Information and control, 6(3), 230-245.

Toda, M. (2007). 感情: 人を動かしている適応プログラム: 東京大学出版会.

Watson, J. B., & Rayner, R. (1920). Conditioned emotional reactions. Journal of Experimental Psychology, 3(1), 1.

Yamane, I. (2007). 恐怖の現象学的心理学. 日本人間関係学会, 人間関係学研究, 5.