The most common symbolic use of the skull is a representation of death. At first impression it carries a negative aura and nowadays more often its portrayal express everything what can be associated with evil in general. However, it can have and another meaning such as life after death, which leads to joy and fulfillment, celebration of life or cheerful memory of the dead one. For instance, a famous day of dead which is celebrated throughout Mexico can be associated more over with joy than sadness or grief.
A symbolic meaning of skull can be related to its openness or identifiablity. A skull as a form is recognizable as part of a human body or as face which express a human person-hood. How does it happen? Human face is one of the most informative stimuli we can perceive. Most of the time even a short one second glimpse of a person's face is enough to tell humans identity, sex, mood, age or direction of attention. Scientists explains this by assuming it as a power of human brain to detect faces we must distinguish among similar visual forms despite substantial changes in appearance arising from changes in bodily position, illumination etc. In short, they assume that identification is particular sensitivity to differences between objects sharing a common basic configuration, in fact such differences must be represented in the brain for both faces and non-face objects (D. Y. Tsao and M.S. Livingstone, 2008). The interesting thing is that human brain is likely to link its bony skull to a face, or even more, let’s say, direct us to what is beneath. So, what makes our brains to identify a bony skull as a Face distinct from non-face object processing?
Human behavior and functional imaging studies reveals that face processing is more “holistic”; that is, faces are represented as non-decomposed wholes, rather than as a combination of independently-represented component parts (eyes, nose, mouth), and the relations between them (Farah et al 1998). Here we can remember the famous classical gestal theorists who were especially interested in understanding of human perception and their explanation of a principle which maintains its nature. According to Kurt Koffka, Wolfgang Kohler and other classics, the human mind forms a percept, or « gestalt « , the whole which independent of its parts, that is, with its own independent existence. It clearly explains why when a bony skull alone is seen as whole face with its references to what is lost or is awaiting. In other words a skull itself reminds its viewers of the unstoppable passage of time and certainty of death. However, in its true meaning it is a symbol of spirituality, and invitation to “Seize the Day”!
If you are interested in futher readings of scientific approach how does our brain produce an image of face, I would recommend:
-D. Y. Tsao and M. S. Livingston (2008) Mechanisms of Face Perception; The Annual Review of Neuroscience 31: 4 11–37;