In the course of writing my dissertation, I come across John Horn's work on Fluid & Crystallized Intelligence over the lifespan back in 1965. This is his thesis that he did while here at University of Illinois, and the copy is in our library. I borrowed it because in his work, he talks about how the factorial structure of psychometric intelligence changes with age.
The first thing I noticed about this work was that it was typewritten! Of course, it is not surprising, since back then, computers were not as available. Its not that. It was because I imagined the painstaking hours it took to generate this written document. What happens when you make a mistake on one single letter halfway? What happens if a fire burns the paper? Did someone digitize? I certainly hope so! How did he do all those calculations? It is extremely humbling to know that others have done this without the huge aid of modern technology and still produced such a marvelous product.
The next thing was that this thesis was signed by Cattell, well-known for formalizing this dual-factor theory of intelligence. Imagine, he touched this piece of paper. This is not sentimentality. This is reverence. I can only hope that my own work will one day be deemed useful to someone, even if only slightly. This is a perennial concern, beyond my control...but it is a strong hope. So much work has been done in the past, of which we mostly overlook or disrespect in our own ego to validate our own thoughts. We must recognize that "there is nothing new under the sun". But what has been given us is the joy of refreshing the old, and progressing into it in greater depths.
The final thing regards what Horn studied. Basically, he found that young adults perform better at tests of fluid intelligence than older adults, and older adults perform better than young adults on tests of crystallized intelligence. This is quite a well-known notion, of which I hear very little about these days. Perhaps it is my own ignorance? I am not sure, but reviewing this work sparks some need in me to investigate this further. Hence the impetus to pursue adolescent research to "fill" up the gap in lifespan studies in cognitive aging, which has focused on older adults. Perhaps much has already been done, I just haven't been in contact with this field or literature...time will tell. I will have to read up more. The graph in this photo is from his thesis. It is hand drawn, and it truly speaks a thousand words.