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We ascertain that cognition is the functional basis of intelligent behaviour as it is exhibited by human beings. Admittedly, the biopsychologists still do not know all details of how human cognition works, but those essential cognitive functions in our brain, which enable the outstanding human capabilities we are so proud of, can yet be described to a quite satisfying extent. We have become acquainted with them to a sufficient extent that we can exploit it for work system design. For this purpose, this article will sum up by suggesting in the following a structure of three cognitive functional levels. High-level cognitive functions: These functions represent the chain of cognitive functions which stand for the mainstream subfunctions to generate any kind of voluntary action in a work process and thereby to impinge on the real world environment.
These subfunctions primarily are in our focus. It is the chain of these subfunctions which take care to determine the situational beliefs, the adjusted goals and constraints, a task agenda, the correspondingly due task (current intent), the resulting action instructions, and the control of these actions. Thus, these are the functions, which provide the visible behaviour of the human operator, being solely based on relevant relevant a-priori knowledge which is innate or might have been acquired beforehand by any learning process. This knowledge can be partially accessed consciously. The most part, though, of a-priori knowledge about motivational contexts which are the drivers for this chain of functions does not become conscious. A study identified four levels of a-priori knowledge in the human brain which become involved for decision-making in any work situation:
• level of innate nature: This level is the very basic one which can hardly be affected by any experiences or education. The pertinent a-priori knowledge may settle personality traits like patience, endurance, openness to experience etc. There is no conscious access to anything explicit of this knowledge.
• emotional level: Together with the level of innate nature this level constitutes the unconscious kernel of our personality, the a-priori knowledge of motivational contexts which are guiding us (most of it located in the amygdala and the mesolimbic system). It develops during the first years of our life and can only be affected by extreme emotional experiences or long lasting influence. There is also no conscious access to anything explicit of this knowledge.
• level of social mind set: This level consists of the a-priori knowledge which helps to make our behaviour socially compliant (predominantly located in the orbitofrontal cortex). The reasoning process and the resulting decisions are being consciously experienced. In essence, the knowledge becomes encoded by continuously learning from social experiences in the course of our life. This level considers the long-term consequences of our voluntary actions.
• level of know-how to communicate: The pertinent a-priori knowledge of this level guides our ways of communication to be in compliance with other a-priori knowledge available in the prefrontal cortex. Again, this knowledge develops by a continuous learning process during our life and any reasoning activity in this context and the behavioural decisions are being consciously experienced.
The a-priori knowledge of the latter three levels and the corresponding subfunctions are highly application-oriented, e.g. dependent on the concrete work demands (work objective) in an application domain. Some of these subfunctions include knowledge processing in the sense of reasoning, thereby taking into account the constraints of limited mental resources. It should be noted that these functions also include voluntary actions for deliberate active acquisition of additional knowledge which may be pursued to be utilised from there on in the work process. Deliberate acquisition of knowledge cannot be done without voluntary actions like reading, for instance, and might become a work process for itself.
Medium-level cognitive functions: These are the functions needed to enable the high-level cognitive functions. They are carried out unconsciously, like learning, if it is not deliberately pursued (learning by doing like we have learned our mother language) and therefore taking place as a concurrent data-driven background processes, or the memory mechanisms including the mechanisms of knowledge representation, retention and retrieval, and the mechanisms of consciousness including those of working memory and attention control.
Low-level cognitive functions: These functions are those of the different kinds of basic information processing elements (neurons) and the structure and internal processing organisation of the neural networking in the human brain. These functions are the basic enablers of the functions of the higher levels. For the discussion of human cognitive functions the focus will mainly lie on the first two higher functional levels of cognition as mentioned above. It would be nice to also cover the third level comprehensively, but this is not possible at the time being. The functions of human cognition pertinent to this level, basic brain elements of information processing and, in particular, the functional organisation of these elements in terms of neural networks as functional units with millions of interacting neurons are still not sufficiently understood in the neuroscience community. This is still a fact, although there are great advances, thanks to the techniques available in combination of electroencephalography (EEG), magnetoencephalography (MEG), positron emission tomography (PET) and functional magnetic resonance tomography (fMRT). These techniques allow the localisation of the time-dependent activation of neural areas associated to certain cognitive tasks with rather good accuracy and in real time. Other techniques allow the investigation of the processes within and around single neurons in great detail, which enables the formulation of computer models. The great gap, though, lies in the fact that there is alarmingly little knowledge of how the billions of neurons actually work together to provide the unique performance of human cognition.
For the purpose of this article this gap will be overcome by covering it on a phenomenological basis, as it is common practise in cognitive science. Therefore, we treat the innermost part of low-level functions more loosely. Looking at the engineers' realm of artificial cognition, it is much easier to carry out the corresponding discussion for the basic functional level of artificial cognition. There, we deal with the technology available as part of the enabling foundations for artificial cognition, keeping in mind that this is a matter of permanent progress of the state of the art with steadily increasing performance of the basic functional elements. This difference in the low-level functions between human and artificial cognition is of great importance, since they essentially provide the explanation for the observable differences in the two higher functional levels between human and machine cognition: The differences mainly lie in the performance of the basic functional elements and the structuring of these elements. This is the reason, too, for the fact that at the time being a one-to-one identity in the functional performance of natural and artificial cognitive systems is not within reach. Consequently, performance differences between human and artificial cognition within the functional levels of cognition have to be carefully accounted for in cognitive system design for the sake of overall system performance.
In the context of high-level functions we have discussed perception, deliberate learning, voluntary action, sensorimotor systems, and communication to some extent. As medium- level functions we have dwelt on the basics of attention control, vigilance, consciousness, unconscious learning, and memory functions. The low-level functions are considered to a certain extent when describing the higher-level functions from a neuropsychological point of view.