Human cognition and the two modes of information processing

Human cognition works on the basis of two modes of information processing. By far the most part of cognition works on the basis of the mode which is characterised by mainly parallel and therefore swift processing. This kind of mode is no surprise, because the connectionistic neural net implementation of human cognition is best suited for this mode. Theoretically, its capacity can hardly be exhausted, but the processing lacks flexibility because of fixed, stored processing patterns (automatisms) and is therefore unqualified for the purpose of creative reasoning. Moreover, it is hardly possible to accurately describe any process of this kind in verbal terms, because the main part of it works unconsciously. Have you thought about what are we really conscious of about our steering wheel actions for lane keeping when driving on the freeway? Automatic activation of this mode can be considered as the standard procedure, although it can be activated consciously, too. The other mode can be characterised by conscious, mainly serial, and therefore slow processing of explicit entities (symbols). This processing mode we would not expect at the first glance in case of a neural net implementation.

Therefore, we will dwell on it in some more detail in the following. This process is limited in capacity, rather tedious, but well-suited for reasoning purposes. It is in the loop, if we are facing complex problems with no solutions at hand. Then, a great deal of data from different memory contents have usually to be put in context in order to consciously figure out how to proceed. It also provides the crucial capability which supports communication by means of languages and which we owe the spectacular progress of science mankind has achieved. For the processing in this mode, two enabling mechanisms play a central role:

• the attention control mechanism and
• the so-called working memory, which will be discussed in the following.

Attention control is an effective mechanism to concentrate the existing resource of cognitive processing on those few external or internal stimuli which are the relevant ones in the light of the motivational contexts. The attended matter can be a content item of the working memory or is just becoming one, originated by external stimuli. We can activate attention control to focus on a particular matter of voluntary choice, subject to ongoing intentions. However, it is also possible that attention is automatically drawn to external stimuli, subject to contexts like:

• motivational contexts,
• conceptual contexts,
• cultural contexts, and
• perceptual contexts.

A mechanism like this is a necessity for the sake of efficiency, because we have only a limited capacity of information processing. Attention control is one of the most complex mechanisms of the brain being still a matter of intense biopsychological research. It can be taken for granted in the meantime that top-down connections onto the neural pathways which are responsible for the processing of sensory inputs, are selectively amplifying and reducing the activation levels. There is some evidence that at least the pre-frontal cortex and the limbic system are partially involved in attention control. This makes sense, because these brain structures are mainly involved in central executive functions like the motivational evaluation of the overall situation concerning the work process, the goal setting, and action planning based on this evaluation. Scientists have shown in cognitive neuroscience experiments that attention to colour and shape produced amplified activity in areas of the ventral visual pathway, and attention to movement produced amplified activity in an area of the dorsal pathway. It is still rather unclear, though, how the detailed implementation looks like. At least, it seems to be verified that the following structures like the reticular formation, thalamus, basal ganglia, gyrus cingulated, parietal lobe and frontal lobe of the neocortex are participating to make happen the phenomenon of attention control.

There are still debates going on about theories of either earlyselection or late-selection along the perception pathways which indicates a lack of a widely accepted view on the cortical processes involved. Certainly, there is a pre-attentive phase of external stimuli processing. In summary, the explanation still relies to a great extent on phenomenological behavioural evidences. When moving on with phenomenological behavioural evidences as a basis, attention is very much associated to the sensory systems, although one has to separate attention in perceptual processes from that in (voluntary) action generation. There is overt and covert attention regarding the process of selecting external stimuli for attention. Overt attention is the act to direct our senses towards a source of relevant stimuli. Usually, the rule applies that the more peripheral a stimulus on the retina, the less the chance to be captured by the attention mechanism. Still, through covert attention we mentally focus on a stimulus which is not simultaneously in the focus of our senses. This brings to light that attention control is a selective mechanism. We cannot simultaneously attend to all external stimuli which are for instance included in what is received on the retina. This also leads to the definition of selective or focused attention, when talking about stimuli processing of one modality.

The term focused attention means that we can only focus at one item at a time, whereas selective attention is used in the context of necessary priority rules to be applied in the light of the existence of various alternatives to attend to, possibly distracting from what primarily has to be attended to. This limitation of the attention resource is not only true for the perceptual processes, but also for the other cognitive processes where attention is involved. In particular, selective and focused attention can become a critical weakness in certain situations. To a great extent, erroneous behaviour of the human operator can be attributed to this weakness. There is the so-called strong-but-wrong error form, for instance. This sometimes fatal type of error can happen when attention is primarily focused on a limited amount of features which, as a result of the phenomenon of habituation regarding context preconceptions, seem to exclusively characterise the encountered situation. The pertinent tasks are expected to be easily mastered by existing preconceptions. It may happen, though, that the expectations might be proven wrong, if all features of that situation were taken into account. This can lead to great surprises of the operator and to catastrophic failures at the worst.

Although attention is immediately shifted to this mismatch, the knowledge about alternative corrective procedures, although existing, might still not be promptly accessible, since the attention is not necessarily immediately directed towards the conceptual lead-in cues which are crucial to adequately identify the situation. In summary, attention control can be misled by existing prevailing preconceptions. A typical situation of that kind can arise when a fire breaks out in a building crowded by assembling people. The crowd is rushing to the door in panic, and the person being first at the door might just be able to open it before the crowd is pressing hard from behind. If this person is being preoccupied by a usual concept that pushing the door is the way to open it, it might just do the wrong thing in this particular case. The door remains closed and, as a consequence, this person and possibly others would be crushed to death before any alternative action can be carried out. Being strongly minded, even further attempts to open the door the same wrong way before eventually looking for possible alternatives is somewhat typical of strong-butwrong errors. Another kind of error due to the limitations of attention control, but without any acute problem solving demand, is the so-called skill-based slip which might occur, if the focus of attention is distracted for some reason from the present task. Probably all of us have experienced it, for instance when driving home from work at night, but having planned to make a little detour to a shop in order to buy something on the way home. It might happen that we think of our family and intentions for the next day, not recognising, that we have passed the intersection, where we should have turned off instead of directly driving home as we do almost every day.

Human cognition and the two modes of information processing

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