Granularity and levels of reality

Let us revisit section 5.2.8. We want to investigate further how a human agent comprehends something. This time, we are more interested in a psychological view, and therefore more focused on the comprehensive abilities of the agent but on the ontological properties of situoids. For this we will investigate some results of modern cognitive psychology, linguistics and discourse analysis. The goal will be to distinguish real from intentional entities in situoid theory.

Whenever a human, intelligent agent uses its cognitive abilities to gather information, for example to read a text, watch a soccer game or follow the steps of a proof, small chunks of information are placed into short term memory, like a single word, a certain move or setting on a game field or a formula. This information is forgotten after approximately 30 seconds, unless rehearsed The Internet Community. Short term memory has only a limited capacity. The number of chunks that can be stored in short term memory has been identified by George A. Miller in his article ``The magical number Seven, plus or minus Two'' as approximately seven. This refers to the amount of meaningful pieces of information or chunks people can reliably remember for a few minutes.

In dijk1, the steps for discourse production are summarized as follows, and they can be, slightly modified, applied to comprehension of entities in general.

• Text/talk is read/heard and interpreted on line, unit by unit (e.g., word for word)
• On the basis of world knowledge, as well as knowledge of words, syntactic structure, overall meaning (topics), discourse structures and aspects of context (goals, etc) such units are assigned provisional meaning
• Meanings of smaller units are combined (and where necessary corrected) into those of bigger units, such as propositions, and sequences of propositions, until the Short Term Memory buffer is (nearly) full.
• The thus interpreted bigger chunks are stored in a Textual Representation (TR) in Episodic Memory.
• Parallel to this understanding of the respective units of the text and the formation of a TR in Episodic Memory, language users activate an old, or construct a new (mental) model of the events or situation the text is about.
• Understanding a text means the construction of such a model: A text is meaningful or understandable when a recipient is able to construct a model for it.
• Apart from meaning elements from the (mental representation of the) text, also information from previous (old) models (= earlier experiences), as well as specific instances of general (socially shared) knowledge help to build up such models.
• Models are both personal (featuring individual knowledge, beliefs, opinions of language users) as well social (applying general, socially shared knowledge), but each model is unique. The same person may construct a different model (=a different interpretation) of the same text tomorrow.
• The whole process of understanding is coordinated by the model language users have of the communicative situation, namely their context model (or simply: context). The context model tells the language user what the aims of the discourse are, who the participants and their roles are, what they know and do not yet know, in what setting the discourse is being understood, and so on. Such crucial information is necessary to understand such diverse properties of discourse as its intonation, lexical and syntactic style, which meanings are expressed or left implicit and what speech acts are being performed.
• Once formed -or updated- a (mental) model of a discourse, language users may generalize such models and thus construct more general, more abstract knowledge structures. It is in this way that language users may learn from their experiences. Of course, they may also make false generalizations, and thus, form prejudices.

In cognitive psychology, these principles are reflected by the concept of chunking. Short term memory with a limited capacity is the place where all incoming information from our senses is analyzed and interpreted first. Chunks of information are assigned a conceptual meaning in short term memory. Perception, comprehension or reasoning takes place in short term memory. The information from short term memory is then stored in the long term memory. However, it cannot always be retrieved. Because short term memory has a limited capacity, the process of assigning conceptual meaning to some whole happens in several chunks. We do not just read in a whole text and start assigning a meaning to it. And we do not perceive all the states of affairs in a situoid at once and start assigning a meaning to the situoid.

This process has to happen in several chunks. Cognitive interpretation, sometimes referred to as comprehension, begins immediately with the perception of the information. The appropriate concepts are then transported to long term memory as soon as the memory capacity of short term memory requires it. Also, the chunks of information have to be semantically connected, in order to assign a meaning to them. We do not simply give some meaning to a state of affairs and place this concept in long term memory, and remove it from short term memory right after. We must assume, that the state of affairs, or at least its interpretation, is still available in short term memory when we start interpreting the next.

This semantic interpretation is purely local. It consists of perceiving chunks of information one after another, and assigning meaning to them and their relations to each other. However, this does not lead us to a conceptual meaning of some whole, a text or a situoid. It does not let us assign the chunk its appropriate role or place in the whole. In cognitive discourse analysis, this concept of global interpretation is made explicit in terms of a semantic macro-structuredijk2. In cognitive psychology, it is explained through consecutive chunking up.

As situoids are comprehensive entities, the same principles apply to them. Therefore, situoids can be described on different levels, from different perspectives, in a lot of different ways. Different ways of describing a situoid result in different models of the situoid.

Imagine a situoid of a plaza. First this situoid is the instance of a universal, say, $plaza_U$. This universal requires of its instances certain features, say, the existence of certain infons like $\langle\langle Tree,x;1\rangle\rangle$, $\langle\langle Fontaine,x;1\rangle\rangle$ or $\langle\langle Person,x;1\rangle\rangle$, stating that there must be a tree, a fountain and a person on the plaza.

Now we imagine to stand on this plaza and describe it to our blind friend, $B$, and call this situoid $s_1$. We state that

• $s_1 :: Plaza_U$
• $s_1 \models \langle\langle Person,person_a;1\rangle\rangle$
• $s_1 \models \langle\langle Has-red-hair,person_a;1\rangle\rangle$
• $s_1 \models \langle\langle Is-attractive,person_a;1\rangle\rangle$
• $s_1 \models \langle\langle Fontaine,fontaine_a;1\rangle\rangle$
• $s_1 \models \langle\langle Is-high,fontaine_a;0\rangle\rangle$
• $s_1 \models \langle\langle Person,person_b;1\rangle\rangle$
• $s_1 \models \langle\langle Walks-from-to,person_b,x_1,x_2;1;c_1\rangle\rangle$
• $s_1 \models \langle\langle Sees,B,s_1;0\rangle\rangle$
• and so on...

Now this may be a detailed description of the plaza ahead, with a description of the persons, the fountain and even a process that involves a person. The existence of a tree is not further described but already acknowledged by stating that $s_1 :: Plaza_U$. Individuals are referred to by name.

Now time has passed, we are back home and recall the plaza to write a report about it in our diary. Let us call the situoid described there $s_2$. Certain features will be lost. We will probably still remember that $s_2::Plaza_U$. Maybe we also remember that there was this attractive red haired person. But the fountain was of no interest to us, so we forgot whether it was high or not. Therefore the situoid $s_2$ is different from $s_1$.

However, there is another view on granularity. In the ontology of GOL it is believed that reality exists in at least three different strata, that can be distinguished by the categories they incorporate. The physical stratum is the most fundamental, and the mental and social strata are founded on this stratum. Properties of the entities in the mental and social strata are supervenient on properties of the physical stratum.

We believe that the physical stratum defines a continuous reality, and situoids may exist in the physical stratum. Entities existing at a point in time, endurants, are constructions of a mind, and do not belong to the physical stratum. They belong to the mental or social stratum. Situations are entities of this kind. However, situoids may participate in the mental stratum, too.