A picture may not be worth a thousand words, but it can certainly capture the essence of dozens of words. Moreover, pictures are much easier to memorize than words. Those memory wizards who put on stage shows owe their success (as do card counters in casinos) to use of gimmicks based on mental pictures. Ordinary readers can use to good effect the practice of making mental images of the meaning of text. The highlighted key words in text, for example, if used as a starting point for mental pictures, then become very useful for memorization. One only has to spot the key words and think of the associated mental images. Sometimes it helps to make mental images of headings and sub-heads. Pictures also become easier to remember when they are clustered into similar groups or when they are chained together to tell a story.
Mental pictures are not the only way to facilitate memory for what you read. I understand that actors use another approach for memorizing their lines for a play, movie, or TV show. Actors “get into the part” and study the meaning of the script in depth, which seems to produce memory automatically for them. When the same script is memorized with mental images, it appears that the text is being looked at from the outside, as something to be memorized. Actors, on the other hand, appear to be looking at the same text from the inside, as something to be experienced. The actors probe the deep meaning of the text, which inevitably involves attending to the exact words. For example, they seem to explore why their character would use a given set of wordsto express a particular thought. This is still a process of association, except that actors are associating words with real meaning and context as opposed to contrived visual image meaning and context.
Both approaches require engagement. The reader has to think hard about what is being read, and that is what helps you to remember what is read.