Although there are clearly many different types of emotions, they all have some common
characteristics. First, emotions are largely non-purposeful and instinctive. The basic emotions
that human's express are shared with most mammals. Anyone who has a pet is aware that it's not
too difficult to tell when the pet is experiencing emotions like anger, anxiety, and happiness.
Second, on the physiological level, as you might expect, emotional behaviors are closely tied to
subcortical structures and the autonomic nervous system. This shouldn't be surprising to you in
that one of the basic characteristics of the autonomic nervous system is the control of nonpurposeful
behaviors such as heart rate and respiration. A third basic characteristic of emotions is
that, to a large degree, they appear to be innate. For example, sociologists have found that facial
expressions associated with the basic emotions such as fear, anger, and happiness are the same
across cultures. Even with cultures that have had very little contact with the "outside world".
Another piece of indirect evidence for the innate nature of emotions is illustrated by a muscle
located above the eyes called Duchenne's muscle. In the last century it was proposed that one
could tell if another person's smile was sincere based on whether or not this muscle contracts. If
it does, the smile is sincere, and if it doesn't the smile is not, and, further, this cannot be
controlled consciously. Research since this time has supported the existence of this "emotional
lie detector" we all carry around like a light bulb on our forehead.
Our focus in this module will be on fear and anxiety. It is not that more positive emotions, like
happiness, are not just as important. It is simply that these other emotions have not been studied
in depth. Further, the behavioral characteristics of emotions such as happiness and love are more
difficult to define empirically than are fear and aggression.