As a little experiment, let's compare readability test results for "If You Were a Dinosaur, My Love", by Rachel Swirsky, 2013;
Simple Measure of Gobbletygook - 11.5th grade lavel
Flesch Kincaid - 8.5th grade level
Lexical Density - 45%
with the first 1,000 words from "Black God's Kiss", by C. L. Moore, 1934;
SMOG - 8.3th grade
Flesch Kincaid - 6.3th grade
Lexical Density - 44%
Both SMOG and Flesch Kincaid measure the use of polysyllabic words, not content. For reference, conversational English is about a 6.0th grade in Flesch Kincaid. Lexical density is a percentage of content words (nouns, verbs, adjectives, and adverbs) to total words. Current fiction averages at 50%.
Autocrit.com was used to quickly generate test results. This limits the amount of text per test to 1000 words. To be consistent, the first 1000 words were chosen.
So why did I do this? It's an attempt to quickly quantify changes that might have happened over time in weird short fiction. Dinosaur was picked as a current story, with Kiss as a pulp story. Although neither are necessarily representative of their times, I wanted to see if there was enough of a difference that further comparisons might be warranted.
What did I expect? Moore, as the pulp writer, would rely on fewer polysyllabic words and more content words than Swirsky, a modern prose poet. This would translate into Moore earning a lower grade level and a high lexical density than Swirsky.
What happened? Moore did have a lower grade level than Swirsky, but they both had a lower than average fiction lexical density.
What's next? - I am thinking of running this with seven pulp shorts from the pre-Cambelline 1930s and seven Clarion graduate modern sff writers to get a better baseline for comparison.
For a point of comparison, and why I think I might be able to catch something by these tests, here are the results for the first 1000 words of Schuyler Hernstrom's "The Challenger's Garland", published in 2014 and a representative work of Pulp Revolution.
SMOG - 7.3th grade
Flesch Kincaid - 4.5th grade
Lexical Density - 49%
Which is closer to what I expect as results from the pulp masters. As before, the grade level is only a measure of polysyllabic word usage and not a measure of content. Hernstrom grapples with adult issues, not elementary school ones. He is in good company at this grade level with celebrated western author Louis L'Amour. Lexical density is higher, but I expected 53% or more from pulps, even though that expectation might need to be revised.