Jeff Hawkins writes in A Thousand Brains (see Reference frames):

Each cortical column can learn models (maps) of complete objects.

Objects are defined by sets of observed features in the upper layer of a cortical column associated with a set of locations of/on the object (lower layer of neurons). If you know the feature, you can determine a location. If you know the location, you can predict the feature.

"Features" are actually links to other reference frames, so it's reference frames all the way down. Neocortex used hierarchy to assemble objects into more complex objects.

Each cortical column can learn hundreds of models.

Reference frames are used to model everything we know, not just physical objects. Thinking is moving between adjacent locations in a reference frame. All knowledge is stored at locations in reference frames.

Attention plays essential role in how the brain learns models. All objects in attention are constantly added to models, either temporary or not.

Note that this last quote implies (I think Hawkins also points this out more explicitly at some point) that "current working memory" is a temporary reference frame.

Hawkins's ideas together with the idea that people can only hold about seven objects in working memory lead me to a speculative conclusion that reference frames of abstract objects (concepts) should look like stars of at most seven points. Some examples:

In my mental model/mental map/reference frame of "aspects/types of safety", there are no "animals". If I lived in the Amazonian jungle, this map would probably include "animals", "insects", "river", "food", and "neighbouring tribe", i. e. would be completely different.

"Rocket" or "hyperloop" are not featured on my reference frame of the means of transport, but probably are present on the equivalent reference frame in Elon Musk's mind.

I think that I feel that reference frames with more than seven concepts don't exist in my mind. For example, the "software quality" is not a reference frame in my mind, I cannot navigate it, I cannot extract its features easily from my memory, despite I've once spent several weeks thinking almost exclusively about this topic, and documented it on Wikiversity. To talk and think about software quality, I need to refer to some notes, wiki pages, and diagrams constantly.

If course, the knowledge about different software qualities is stored somehow in some reference frames in my mind because if I think long and hard, I can extract, perhaps, 15-20 qualities from my memory. But there is probably some implicit second hierarchy of concepts between the concept "software quality" and the actual qualities, or, more likely, some mess of "proto-", "fuzzy" frames. Mental navigation in such a landscape is energetically hard, it is "real thinking". The mental navigation in crisper, simpler frames of at most seven features is effortless, "automatic".

The first implication of this conclusion is that overly connected evergreen notes don't reflect actual reference frames in my mind and therefore don't serve the mind in "mental navigation", recall, solution finding, etc.

The second implication is the new way to look at the famous "two-pizza team" rule. Traditionally, the team size of 8 is justified by the growing number of communications. But maybe people cannot place more than 7 colleagues well on their "team" reference frame?

Implications in systems thinking: Explaining the power of systems thinking practices using reference frames.