3.4. Perception, memory, and decision

Let us look at the locomotion of bacteria in more detail: It is propelled by one or more fast rotating flagella. After having moved forward in any direction some time, flagellar rotation shifts to the opposite direction, quasi to ‘backwards’, which results in a kind of lurching by which the bacterium’s posture in space changes. After a short time, the flagellar rotation again shifts its direction, and the bacterium again moves straightforward in a further random direction. And so on: Linear motion again and again alternates with lurching, and after each lurching phase the bacterium moves in a new random direction. Already this random motion has a benefit: the bacterium avoids its own excrement to enrich in its surrounding.

How does this sequence of random changes of direction turn to a targeted movement? Some bacteria have receptor molecules in their outer membrane; these receptors go over into the interior of the cell so that information can be transmitted from outside to inside. When a ligand, e.g., a saccharide molecule is bound to the receptor, then the interior part of the receptor molecule changes its shape. This results in a cascade of biochemical processes in the cell which at the end prolongs the straightforward phase of the flagellar movement. Every saccharide molecule binding to one of the receptor molecules has this effect, and the result is that movement phases towards a higher saccharide concentration are longer than movement phases in the opposite direction. So the bacterium statistically moves towards a higher concentration of the nutrient.

The shape change of a receptor molecule due to a ligand binding to it lasts only some time; then the receptor changes back to its original shape and is operational again. This can be taken as a kind of short-term memory: Information from outside results in a structural change in the inside of a living thing, and this change is erased after a short time (nothing else happens to us, save that we have s special organ for such internal changes by information: the brain). We find this in non-living nature as well: A footprint in sand at the seashore is erased by waves after a short time. In the bacterium and in the human brain, however, the time when information is erased is (mainly) determined not by external but by internal processes. That’s an important difference because these internal processes can be optimized by the evolution.

A bacterium’s ability to detect substances relevant for survival by means of receptor molecules can be regarded as an early evolutionary stage of perception. Of course, this perception is not at all associated with consciousness. It is immediately coupled with re-action and gets sense only by this coupling. Active motility of the living thing and its ability to actively change the direction of movement – even if originally only randomly – forms the basis on which information from outside can, via internal processes, influence a living thing’s own movements so that the movements are beneficial for survival. Not receptors or simple kinds sense organs stood at the beginning of the evolution of perception and cognition, but the self-activity of living things.

Although perception and action, at the early stage of evolution, are closely coupled, there is nevertheless needed some time for the internal processes between – and these processes can be influenced by other internal processes, Imagine, for example, a bacterium that has receptors for a nutrient, but also receptors for a substance that should better be avoided (‘pollutant’). When a molecule of the pollutant is bounded, the forward phase of the flagellar movement becomes shorter, lurching starts earlier, with the effect that the bacterium tendentially moves in the direction of decreasing concentration of the pollutant. But what happens if nutrient and pollutant are detected at the same time?

In such a case that might not be unlikely, two internal control processes get in competition with each other, and it must anyway come to a decision of how the bacterium will eventually move. By the way, also when neither a nutrient nor a pollutant is detected, that is, during completely ‘chaotic’ movement, the point in time at which forward movement shifts into lurching is a decision that comes about in the interior of the bacterium, thus we must say: It’s the bacterium’s decision. Likewise, we will call a human’s behavioral decision ‘his’ or ‘her’ decision if we assume the main causes or reasons for it to be in the person.

Self-activity is necessarily associated with decision making. I do not claim that such decisions are ‘free’ in any sense – they are determined by their causes just as all the decisions that permanently come about around us, e.g., the decision of whether or not it rains. Decisions of living things, however, are characterized by the fact that they are mainly caused within them, by their internal processes; therefore we can call them their own decisions. External information is internally processed before it can influence a living thing’s own behavioral decisions. Information must be evaluated in terms of whether it means advantage or disadvantage for survival and well-being. In other words: A living thing needs to understand information.

Considering the term ‘decision’, it must however be said: Decisions exist only from the perspective of someone able to imagine that things could be different than they are: It is just raining, but I can imagine that it isn’t. However, the fact that it is raining was completely predetermined by previously existing physical causes – there was no alternative. Looked at in this light, there are no decisions: All events necessarily happen because of their causes; they are completely determined by them. Likewise, a living thing, at every moment, necessarily behaves in the way it does – there is no choice. This is true for human behavior as well.

Nevertheless, we have the strong intuition that we are able to make decisions, and moreover, that we sometimes to our sorrow are required to decide something. I don’t believe that this intuition is a pure illusion. Its basis is something characteristic of living things: the possibility of antagonistic processes within their self-regulation – processes potentially leading to opposite (re-) actions. Suchlike antagonistic processes can be in an equilibrium for some time, i.e., in a standoff. This may then result in a state of indecisiveness and, in a conscious mind, lead to the experience of being conflicting. I will address this issue more extensively in a later chapter.


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