Metaphors of thought
There have been various metaphors, often linked to the technology of the time, that have been used to help us understand the mental events that constitute thinking. For example, Sigmund Freud used a hydraulic model of the mind to understand how repressed thoughts and feelings could manifest themselves in dreams and neurotic behaviours (Freud, 1954). This was like a fluid in a pipe being compressed and hence spurting out somewhere else. An early information processing model saw the mind as an early telephone exchange where input processes were like subscribers ringing the exchange where the operator would connect to the subscriber by plugging a cable into a socket in the exchange and asking what number they wanted. The operator would then connect the subscriber to the number by plugging another cable into another socket. The mind was the telephone operator passing information from input to output. But that doesn't explain how the operator works.
In the second half of the 20th century, computers provided a much richer model of how thinking might work. Instead of having a model that had unexplained gaps such as the telephone exchange model, computers were virtual machines that could perform a variety of different tasks depending on the software installed. Thus, a single machine can be a word processor, a calculator, a designer, a chess player, a movie player, a car driver, and so on. Descartes (1637/1998) regarded a person as a machine animated by an insubstantial soul (a ‘ghost in the machine'). By distinguishing software from hardware in a computer, suddenly the ghost and the machine could be combined. Furthermore, a computer works by performing computations. Vision works by computing light intensities: from that - computing lines, edges, curves; from that - computing planes and surface orientations; from that - computing 3D volumes (Marr, 1982). So far, this type of computation involves serial, bottom-up processing', the results of one process passes to the next stage that computes an output that passes to the next stage, and so on. However, stored knowledge will kick in to help vision identify what it is looking at and where it is (top-down processing). This allows us to process multiple sources of information at the same time thus speeding up the task of identifying objects, understanding speech, flying aeroplanes, or whatever.
Mental models of the world
Processing information to generate a virtual reality model of the world usually means generating a series of mental representations. If you are planning where to go on holiday then you are generating a number of mental representations about what kind of holidays one you want, what kinds of activities you want to engage in, what kind of weather you are hoping to have, where you want to stay, how much you want to pay, how to get there, the timings involved. If the mental representation is complete, then the virtual reality model you have generated in your head should conform broadly to the actual reality that you will experience in the world, and problems that might arise can be solved before you even start. By mentally representing the world, you can plan your holiday, design a house, prepare what to say at an interview - all before actually going on holiday, building a house or taking part in the interview. We are able to do this because our experience of the world has allowed us to learn what to expect and thus predict the near future. The ability to represent the world is due to the fact that our brains are ‘prediction machines’ (Clark, 2013; Hinton, 2017a).
Relative vs absolute thinking
There are many examples from decision making to risk taking to perception, and so on, that show that our thinking is relative
figure 1.3 Effects of judgements of size of the grey circle due to the context. It is small relative to the large black circles and large relative to the small ones. They are, however, identical.
rather than absolute. Figure 1.3 is an example from visual perception. We tend to make local comparisons rather than absolute ones. This is true even at a physiological level. For example, if you have three bowls of water, one hot, one cold and one at room temperature and you put one hand in the hot water and one in the cold water and hold them there for a short while, then take them out and plunge them in the water at room temperature, the hand that was in the cold water will find the room temperature water hot whereas the other hand will find it cold. Relative to the temperature of the water in the first bowl, the perceived temperature in the room-temperature bowl is cold or hot. Similarly, if you are poor, €100 is a lot of money. If you are rich, €100 is pocket money. If you are buying a house, you might offer €305,000 but just to make sure you could up it to €308,000. Another €3,000 is a relatively small fraction of the house price. For any other purchase that you might make, €3,000 is a lot of money.
The ease with which something comes to mind makes it seem relatively important (see Chapter 5). If there is a report of a child dying due to an infection caught at an open farm where animals are handled, parents might think twice about going on an outing to an open farm and choose the beach instead. Thus, the visit to the farm seems relatively more dangerous than driving to the beach. However, such infections are exceptionally rare whereas car accidents are very common.
