Under the Microscope: Our body has inbuilt mechanisms to help us to protect ourselves against dangers in the environment. Thus, when we perceive a threat in our immediate environment, for example an angry aggressive dog, we have an immediate involuntary hormonal response that chemically prepares our body for immediate action - either to fight the threat or to flee from it.
This is called the "fight or flight" response. Protecting ourselves from threats in our environment is obviously of vital importance. But how do we protect ourselves from threats that we do not directly perceive?
Well, we can do something about this too because we may detect the threat in our environment indirectly by perceiving fear in the face a companion who has already perceived the threat. Indeed evolution has equipped us with a hair-trigger response to perceiving fear in someone else's face. According to a study published in the Journal of Science last December, authored by P Whalen, seeing the enlarged whites of fear-whitened eyes is sufficient to activate a fear-related structure in the brain called the amygdala.
In evolutionary terms the amygdala is an ancient almond-shaped structure buried deep in the brain and found in all vertebrates. Fear is an essential incentive to help us to avoid danger. The amygdala is crucial for feeling fear and for priming the body to physically respond to danger. The amygdala is also involved in other emotions. There is some evidence that malfunctioning of the amygdala may play a part in autism and over-activity of the amygdala may play a role in anxiety disorders. The sensitivity of the amygdala to a fearful expression on someone else's face is helpful to you because whatever has alarmed your friend may also be a danger to you. The amygdala is so good at this detection that it responds automatically even before the conscious part of the brain has worked out what is happening. In other words, sensing fear is so important to survival that evolution has automated it.
Angry faces don't activate the amygdala as much as scared or surprised eyes. Eyes in the latter categories show more white than angry or happy eyes. Volunteers were shown many images of neutral emotion eyes interspersed with images of scared eyes. The images of the scared eyes were flashed in so quickly that the volunteers were not conscious of them. The results showed that the volunteers' amygdalas responded to the scared eyes. Amygdala response was monitored by functional magnetic resonance imaging to measure the blood flow in specific regions of the brain.
Much has been learned about how the amygdala works by studying patients with damage to this part of the brain. A study published by R Adolphs and others in the journal Nature, January 2005, describes the behaviour of a patient (SM) who has lesions in the amygdala. SM cannot recognise fear from facial expression and the study shows that this is because she doesn't look spontaneously towards the eyes on the face. Normal people always look immediately at the eye region of a face. When shown a face with a clear expression of terror, she concentrates on the nose and mouth regions and ignores the wide scared eyes. Visual cues provided by the eyes are particularly important for the recognition of fear. Other emotions registered on a face can be recognised without looking at the eyes, eg a smile.
Surprisingly when SM was instructed to "look at the eyes" she could recognise fear - she still knows what fear "looks like". However, unless continually prompted to look at the eyes she very soon reverted to taking all her cues from other areas of the face and ignoring the eyes. It seems therefore that the damage to the amygdala has altered how SM explores and pays attention to the face rather than how she analyses and categorises.
Fear/anxiety is a primary human emotion, others being happiness/joy, anger/irritation, sadness/grief, and disgust/ hatred. From these, more complex emotions can be derived. Traditionally in the West we have tended to define the human mentality in terms of thought, intelligence and knowledge. However, it becomes more easily conceivable every year that passes that computer advances will eventually produce artificial intelligence that will rival, or even outperform, human intelligence - already we have computers that can beat expert humans at chess. When/if that day arrives, how then will we define the uniqueness of our species?
We might well use emotions as a measure of our species. We are those beings that love, grieve over the loss of a loved one, feel shame at behaving badly and fear in the face of danger.
Fear and anxiety may be regarded as two different degrees of the same state. Fear is an intense emotion felt in the presence of an immediate and real threat and produces responses that increase an individual's chances of surviving these threats.
Anxiety is a vague and unpleasant emotion that reflects apprehension, distress and unfocused fears of no one thing in particular. It can be caused by various situations involving perceived unpredictable or uncontrollable situations in one's life. Temporary anxiety is normal and has no lasting effects but persistent or chronic anxiety can lead to pathological conditions.
Unnecessary anxiety is a life-wasting thing, but it seems to me that the pressures of modern living have greatly increased the average person's anxiety levels. In acknowledgement of this, people parting from each other are now as likely to say "take it easy" as to bid a simple "goodbye".
William Reville is associate professor of biochemistry and public awareness of science officer at UCC .