It is somewhat surprising that the knowledge which is common to software developers in the context of software development does not readily translate itself to the views expressed on this site. This is, after all (if we are honest), largely an extension of a site dedicated to questions about software development.
It is central to many software development methodologies to pay attention to the issues arising out of managing complexities, and human ability to grapple with them, due to limited capacity of the human attention span.
Much of what propaganda deals with is overwhelming the capacity of the attention span in order to make difficult for most people to grasp ideas which go counter to the propaganda's narrative.
Open societies (like the liberal democracies ) are based on the principle that allowing any ideas to air will make the cost of isolating most people from good ideas insurmountable. So the people end up being exposed to both good ideas and bad ideas and only retain the good ones.
Closed societies (like 1-party states and other societies with heavily-censored public discourse) are based on the principle that the society can be motivated to go along with the central government's premises as long as other ideas simply don't get an airing.
Communist countries (i.e. the ones ruled by the Communist Party and referring to themselves as "socialist"), during the Cold War, were a perfect test-bed for limiting access to information. Not only because the cheapest means of communication during those times were largely broadcast-based, but also because their languages were too different from the languages spoken in the West.
The Role of Language
The language barrier acted as an additional information barrier of entry for most information from the West to the Communist societies. Most information that was allowed through was technical and could be understood by producing professional translations or (for the more cutting edge specialists) by allowing reading to be done with a dictionary by one's side.
This created an asymmetrical influence model. In which the Communist countries could learn Western European languages and exhort attention span bombardment of the impressionable Westerners, while the West had no such ability to influence the impressionable residents of the Communist countries.
Because the Communist countries saw the World Revolution as the ultimate ideological goal, this appeared to create an advantage. Although it didn't quite materialize because they didn't correctly estimate just how much the language barrier was part of the influence. Possibly because they overestimated the objective value of their ideology.
For example, the Communists had a lot of sympathies in India (Gandhi called himself a socialist ). But the socialist notions could not silence all messages because, as a former British colony, it had many educated Indian citizens who had access to all that which was said English.
I don't want to sound like I am pretending that English colonialism was a positive thing for India. I think of it more as a disease which immunized India from the scourge.
The West Played Catch-up
Because the Communist countries had the additional information warfare advantage of language, they were more successful at infiltrating open societies of the West.
Once the West realized that they were being targeted for an ideological destruction (because again, the Communists' stated goal was a World Revolution, they launched both domestic programs to remind its residents of the values which made Western societies what they were (thereby regaining some of the ground of the collective attention span) and limited distribution of translations of news/books/etc. into languages native to the Communist countries. Although I believe there was more emphasis on Eastern Europe than on China. But I could be wrong about that.
Why Did it Break
One of the main factors for the collapse of the closed societies' propaganda model was the rapid expansion of cheap means of reproduction of recorded communications (both audio and print). Xerox machines and tape recorders made it much cheaper to share Western messaging in previously-closed societies.
The development of the Internet had some of the reverse effect. It erased so much of the language barrier that it made it possible for the previously-closed societies to influence the open societies. And it made reproduction of information accessible to all.
This has led to what is now known as "information warfare." Which is an attempt by all societies to gain footing in the collective attention span of others. Rather than a conversation, it is now a competition of shouting matches.
How It's Getting Fixed
But the attention span is still limited. So people cannot process more than a small fragment of the available information. This created a market for services curating information in the sea of all available information.
There are competing claims that
- curation now serves the role that the censors used to do
- or that the curation simply filters out the noise
Unfortunately it does both and, while it has its problems, it's also a necessary tool to deal with the fact that the attention span is limited.