Do we need and what is the theoretical foundation of Proximity

In the proxemic interaction paper, we hear about 8 concepts:

1. Incorporating the fixed- and semi-fixed feature space;
2. Interpreting directed attention to people and objects;
3. Supporting fine grained explicit interaction;
4. Interpreting continuous movements or discrete proxemic zones.
5. Moving from awareness to direct interaction;
6. Leveraging people’s Identity
7. Mediating people’s simultaneous interaction.
8. Difference in perceiving and interpreting Proxemics

However, these concepts seem not enough to form a well-defined theory about how to design using Proximity. And before that we might ask: do we really need a theory? The 8 concepts look intuitive such as interpreting continuous movements or discrete proxemic zones. In my opinion, we do not know whether a theory is necessary unless we try to find one. I googled "cognitive psycology proximity" and searched a paper named The Proximity Compatibility Principle: Its Psychological Foundation and Relevance to Display Design. (But I have not been able to download it) I am interested at what theory we can find or propose with the use of Proximity.