This is part of a special series of posts on the digital history of psychology from members of the PsyBorgs Lab at York University, in Toronto, Canada. The full series of posts can be found here.

Digital history seems hard to a lot of people. All those fancy computer programs to count and filter and graph data seem complicated and difficult to learn. But it need not be that way. You can get started on basic digital history of psychology right now with nothing more complicated than the web browser you are using to read this message.

Let me show you how: First, go to the Google Ngrams web page (in another browser tab, so that you can continue to read this post as well).  Ngrams is a program that scans the vast holdings of Google Books for words that you select, and then plots them on a line graph. When you have the Ngrams page up, delete the default words  “Albert Einstein,Sherlock Holmes,Frankenstein” from the search box and replace them with the words “phrenology, mesmerism, hypnosis”  (no quotation marks, but be sure to include the commas). Set the date range to between 1800 and 1900. Make sure the corpus is set to “English,” and leave the “smoothing” at the default value of 3. Click on the “Search lots of books” button.

You should get a graph that looks something like this (click on the graph to enlarge it):

You can see that immediately see that phrenology had its peak popularity (in English-language published books) in the late 1830s, and then began to fall off rapidly. It is important to note, on the y-axis, that this peak was only about 2/10,000ths of a percent of all words that appeared, but that was its peak none the less. It also had a secondary peak in the late 1840s, at just about the same time as mesmerism began its own rise. Indeed, some people of the time (including Ada Lovelace of computing history fame) wrote of “phreno-mesmerism”; the two practices began to merge in the public mind. They both fell off in the 1850s to a kind of “background” level of about 4/100,000ths of a percent for the rest of the century. In about 1885, however, a new discipline called “hypnosis” began to rise, surpassing both of the older practices in the late 1880s, and reaching its (19th-century) peak in the mid-1890s.

There is problem with doing the graph this way, however. Many authors  discussed these three ideas using alternate forms of the words: phrenologist instead of phrenology, mesmeric instead of mesmerism, hypnotize instead of hypnotism, etc. So we need to include those forms in our search as well. Go back to the Ngrams search box and insert this instead: phrenology+phrenological+phrenologist, mesmerism+mesmeric+mesmerist+mesmerize+mesmerized, hypnotism+hypnotize+hypnotized+hypnotizer+hypnotist. That covers most of the variants. Be sure to click the “Search lots of books” button. Now your graph should look like this:

This graph is not that different from the first one, except that the main peak for mesmerism and its variants (let’s call this mesmerism+) now exceeds the secondary peak for phrenology+ around 1850 (because, as it turns out, “mesmeric” was actually used more frequently than the base term “mesmerism”). Note also that there is a bit more of a secondary peak for mesmerism+ around 1890.

Now we are going to vary the corpus of books we use. Go back to the Ngrams page and change the corpus “English” to the corpus “American English.” This includes only books that were published in the US. Remember to click the “Search lots of books” button.

Note that phrenology+, at its peak in the 1830s, was a little more popular in America (or at least in American books) than in the English speaking world as a whole (.0005% vs. .0004%). Also, mesmerism+ was less popular in America (.00023% vs. .00028%), making its main peak lower than phrenology+’s secondary peak around 1850. In addition, there’s not very much of a secondary bump for mesmerism+ in the 1890s.

Now change the corpus to British English (and click “Search lots of books”).

Here we see a quite different different pattern. In Britain, mesmerism+ in the 1850s was nearly as popular  as phrenology+ had been in the 1830s. Also, there is a large secondary peak for mesmerism+ in the mid-1880s. It seems that the Brits, more than the Yanks, enjoyed writing (and presumably reading) about mesmerism.

Now we are going to limit the kind of books we include to just fictional works. Change the corpus to “English Fiction.”

It seems that phrenology+ never really caught the literary imagination, even when it was at its peak popularity in the 1830s. Mesmerism+, by contrast, had two major peaks in the fictional literature. One was in the 1850s (consider, for instance, Edgar Allen Poe’s short story, “Mesmeric Revelation,” 1850).   A second peak appeared in the 1880s (e.g., one of the most popular novels of the 19th century, Edward Bellamy’s Looking Backward (1887), begins with a protagonist who is put into a mesmeric trance for over 100 years). Unfortunately, it is not possible in the current version of Ngrams to split the English Fiction corpus into American and British subtypes to see if the national patterns were different from each other.

So, you may be asking why I titled this post “Are We Living in a Golden Age of Mesmerism?” It is obvious to everyone that mesmerism is long-discredited and no one would regard this as being a good time for that antiquated practice. However, if you change the date range to between 1800 and 2000 (and leave the corpus at English Fiction) you will see why I asked the question.

The first thing to notice, of course, is that during most of the 20th century hypnotism+ was far more popular in fiction than were either phrenology+ or mesmerism+. Hypnotism+ enjoyed successively higher peaks in 1920, the early 1940s, and then again in the 1970s. After that, however, something unexpected happened: hypnotism+ began to fall off and mesmerism+, which had quietly been on the rise again (in fiction, recall), since the late 1950s, actually surpassed hypnotism+ around 1980. Mesmerism+ continued its climb through the 1990s and, as of the year 2000, it was more than 50% more frequent than hypnosis+ in the English Fiction corpus (.00035% vs. .00022%). Who would have guessed?

So there is a little bit of digital history of psychology for you to ponder. Here are some additional exercises for you to try on your own:

(1) Many people spell “mesmerism” with a capital “M” because it was named after Anton Mesmer. Change the corpus back to “English” and reset the date range back to between 1800 and 1900. Then search only “mesmer,” but tick the little “case-insensitive” box next to the search box. (Then click on the “Search lots of books” button.) We could re-do all the searches we did above with this additional information (although you cannot use + and case-insensitive in the same search in the current version of Ngrams). Also, the British often use the spellings “mesmerise” and “hypnotise.”

(2)  Re-enter in the search box that long list of variants of phrenology, mesmerism, and hypnosis that we had before. Then add “psychology” to the list (with a comma in front of it). See how its frequency compares to the other three practices. Then, extend the date range to 2000 and generate a new graph.

(3) Change the “smoothing” to 1 or even 0. The smoothing function takes averages over a range of years in order to eliminate much of the random year-by-year variation or “noise.” This makes the graph easier to read. Next, change “smoothing” to 5 or even 10 years.

(4) Change the date range to between 1900 and 2000. Then search  “cognitive, behavioral”. Why do you think the lines crossed when they did? Add “social,” “developmental,” “personality,” etc. ?