ABSTRACT
Day and night, the sensory apparatus of the nose, eyes, ears, skin and deep tissue steadily detects the nature of the world in which we live. This mass of unsensored data arrives continuously in the brain and spinal cord. Only a small selected fraction of the total available information affects our behaviour. A different small fraction is selected and made available for conscious perception. The manner of this selection is the subject of this chapter. A sequence of processes, alerting, orientation and attention, precedes conscious perception. It seems intuitively obvious that tissue damage and injury take precedence in attracting attention and inevitably result in conscious perceived pain. What appears intuitively obvious conflicts with the facts. The placebo effect shows that conscious perception can be dominated by expectations which may conflict with the sense data. Furthermore, observations of human and animal behaviour repeatedly demonstrate that overall behaviour may relate to expectations learned from past experience rather than to the moment by moment information provided by the sense data.
