Understanding the Brain p. 3 Josephson
be likely to achieve a target result. This choice of field to explore is one aspect of the model, and has its
correlate in the physical system architecture.
It has previously been noted that the details of processes are typically context dependent, which requires a
mechanism whereby different systems can be activated in different contexts, in conjunction with processes
defining a context in suitable ways. In addition, the learning process can be enhanced by means of mechanisms
that encourage remaining in a particular context or task situation long enough for the details of the relevant
processes to be properly established.
We can characterise the hyperstructure processes as building up a hierarchy of resources, each stage providing
resources needed for the next level. A process such as learning to walk can fairly obviously be seen as a process
involving the generation of resources of specific types in specified ways. One of the principles involved can be
characterised as a moving target principle in that the target is initially a simple one such as being able to stand
up in balance, but when this target has been accomplished a new target comes into view, such as taking a step.
Later on we will be discussing how processes as language acquisition can be structured in similar ways.
Such a regulated development, with each stage limited by the demand that specific targets be met, seems more
likely to be able to achieve an outcome such as human language than the anything can be achieved just by
adding a few more layers to the neural network concept of some network modellers (cf. Quartz and Sejnowski
1997). It also provides in principle (subject to the characterisation of the types of systems and the observer
mechanisms causing one level to emerge from another) a more precise specification of how language could
develop than the approach of Arbib (2000) which argues that language is the anticipated outcome of combining
a certain collection of skills but is unclear about how the combination of skills comes about. In the present
picture, everything is implicit in the collection of abstract descriptions, which are similar to a collection of
instructions for building some multi-level structure, with diagrams of how the various parts fit together at the
various levels. In other words, the physical nervous system is a realisation of an abstract scheme which is itself
composed of many interrelated parts, somewhat in the way that a computer program is a realisation of the
specification provided by its source code in a high-level programming language.
A variant mechanism for creating hierarchical structures involves problem-solving processes, again assumed to
be associated with specialised abstractions, invoked when a process taking place meets some kind of obstacle.
This kind of process differs from the hyperstructure processes in being driven primarily by environmental factors
rather than developmental mechanisms. Dealing with obstacles can be facilitated by an equivalent to the frame
mechanism used in computer programming; this involves the creation of a frame that represents the details of
the problem, and the situation to which return will be made.
4. Role of the architecture
The role played by the neural architecture is implicit in the above account, and in this section we make its role
explicit through examples. An example of a place where the architecture is relevant is in the idea that search
processes can owe their efficiency in knowing which field to explore for systems to use. One device for
achieving such selective investigation is to have a scheme whereby particular neural systems are assigned
particular roles, and to arrange for some signal to be present which can make the relevant systems selectively
available, while some other signal picks out a subset of these systems specific to the current context. More
generally, any element of an abstraction stating which type of entity is required for a specific application can be
implemented by an architecture that effectively assigns specific types of system to specific roles within the
collection of abstractions.