Similarly, when we hear traffic start up early in the morning, we are conscious of the sound. But as the roar of starting lorries merges into a steady hum, we get used (habituated) to the sound and soon we are no longer conscious of it. But if there is a CHANGE, a sudden silence, or a sudden crash, we are again aware (conscious) of the traffic.

Thus consciousness is OUR RUNNING RECORD OF CHANGE OF INPUT TO THE NERVOUS SYSTEM ... regular, routine input evokes automatic, subconscious response, while consciousness is triggered by non-routine, unusual stimulus, which evades our habitual response system, and penetrates to the centre, to the cerebral cortex, engaging the imagination which continually integrates the non-routine input from our senses, weaving it into the 360-degree glorious technicolor 'big picture' which we call 'reality'!

The nature of the negative-feedback processes regulating our behaviour are such that the brain acts continually to reduce input from the internal environment by outputting the appropriate pattern of signals to the muscles for the sequence of behaviour needed to correct the imbalance signalled by the flow from within.

For instance, urgent (that is unusually frequent) signals from within indicating LOW blood-sugar levels will generate 'seek food' behaviour (looking around) and when input from the peripheral senses (eyes, nose) indicates the contrast (rapid change of input) between red apple and green foliage, say, the streams of input from interior and exterior are combined and processed, finally to emerge and trigger the pattern and sequence of muscular activity which carries the fruit to the mouth and consumes it, thus RAISING the blood-sugar level. A different pattern of input -- say low input from within due to HIGH blood-sugar levels combined with the same external input, might generate the pattern of muscular activity which puts the apple in a pocket for later.

'Attention' is in fact 'attenuation' of input: if a light flashes, say, or a bell rings, the change in rate of input evades the automatic responses and penetrates to the cortex, engaging the imagination which has the function of initiating non-automatic, original behaviour to attenuate (attend to) the sudden influx and reduce the flow of input to a steady stream, dealt with routinely by the automatic systems, freeing the cortex to prepare for further sudden developments.

The biological function of consciousness is prediction and the integration and initiation of non-routine behaviour to enable rapid adaptation to rapidly changing circumstances.

Since consciousness is our response to changing input, while regular, routine, unchanging input is coped with habitually, that is SUB-consciously, it follows that WHAT IS AROUND ALL THE TIME IS INVISIBLE ... it is impossible to see the wood for the trees, and people can be manipulated via their habit-forming systems by repetition. So-called subliminal advertising is not hidden from view, which would be self-defeating, but on the contrary is ubiquitous, and therefore invisible. Guinness is good for you: however obvious the lie, sufficient repetition gets it swallowed by the subconscious (automatic) response system, unless some non-routine event (reading drugwar notes) triggers attention, engages the imagination, and breaks the habit.