Towel Model vs. Jelly Model: Understanding Information Systems
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The two basic classes of information systems can be described by models — the towel model and the jelly model. In the towel model a towel is laid out flat on to a table and a small bowl of ink is placed nearby. A spoonful of ink is taken from the bowl and poured on to the surface of the towel at a specified place. The ink represents the ‘information input’ which can be specified by reference to coordinates taken along the edge of the towel. The information input is recorded as an ink stain. A number of different inputs are made one after another so that the towel comes to bear a number of ink stains. The towel simply records what has happened to it, and since the ink is immediately absorbed by the towel there is, at the end, an accurate record of the inputs.
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The towel system is the sort of accurate memory system which one uses in a computer. The incoming information is recorded without being altered in any way. A separate processor then uses this stored information according to its programmed instructions. It is the processor that changes the information around. In the jelly model the towel is replaced by a large shallow dish of ordinary jelly or gelatine. This time the bowl of ink is heated. When a spoonful of hot ink is poured on to the jelly, it melts the jelly’s surface. However, as the ink cools, it stops melting the jelly. When the cooling ink and melted jelly are poured off a shallow depression is left which marks where the ink was placed, and this depression corresponds to the ink stain in the towel model, as a record of input.
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If succeeding spoonfuls of ink are poured on to widely separated parts of the jelly surface, the final result is very much like the towel model, but if the spoonfuls overlap then something quite different happens. Instead of staying exactly where it has been placed, the incoming ink flows into an already existing depression and tends to make it deeper. At the end, instead of having a number of separate depressions, one has a sort of continuous channel which is sculpted into the surface of the jelly, much as a river is sculpted into the landscape. The difference between the two types of recording system is considerable. With the towel model the ink stays where it is placed, so that, at the end, there is a good record of what has happened. In the jelly model, however, the ink flows along the channels already formed in the surface. The jelly model is, therefore, a bad recording system since it does not record accurately but changes information around according to what has happened before. This is information processing, and since the recording surface is now doing its own processing there is no need for an outside processor. Thus, the jelly model acts as an information processor or ‘thinking system’, although the surface is quite passive. All it does is to provide an opportunity for incoming information to organise itself into a pattern.
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On different occasions I have asked some 5,000 scientists and mathematicians to give me a definition of pattern. Most of the definitions contain the necessary elements of order, recognition, repetition, and predictability. All these can be included under a very simple definition of a pattern: “a pattern exists when the probability of one specific state succeeding another specified state is greater than chance”.
