Words can be repeated easily, but are understood with more difficulty. The sense must be determined partly by context, and then the specific function of the word refined by closer examination of how it is used, and how it differs in meaning from other similarly functioning words. Listen, repeat, guess, venture a usage, test, refine, test, utilise. Search for meaning, not noise; reduce uncertainty rather than increase it. Concepts, not tropes.
Thus the word stores of individuals vary: not all people will be able to use precision instruments, or even see the need for them. 40,000 tools is a lot to carry in a brain. A passable job, rough and ready, can be achieved with 9,000. Vocabulary stores are good predictors of general ability, and their high storage cost must be worth it.
Looking across generations is harder. My brothers and I laughed at my grandmother for referring to a drinking glass as “a tumbler” and mocked her for insisting such vessels always be placed on a lace doily, so as to leave no ring marks on the dining table. Testing contemporaries on dated usages is unfair. Does that mean we cannot determine anything about the vocabularies of today compared with those of our grandparents?
I was pondering these weighty matters when once again the familiar urchin messenger boy arrived with yet another missive from the grand house of Woodley of Menie. I cannot be sure, but I think the miscreant boy calls on the under kitchen maid first, and only afterwards comes round to knock on the front door, which may account for his flushed countenance.
What Woodley and his dining companions Fernandes, Figueredo and Meisenberg have done is to tie together four disparate but crucially related aspects of vocabulary: the extent to which a word can be defined (intelligence loaded vocabulary test), the historical birth of the word (when it first shows up in dictionaries, which they call “word age”); levels of national literacy and the extent to which it is now used in written texts (Ngram usage measures 1850-2005). Crafty, this gang. Here are a few highlights before you look at the final corrections on the not yet finished proofs.
Michael A. Woodley of Menie, Heitor B. F. Fernandes, Aurelio José Figueredo and
Gerhard Meisenberg “By their words ye shall know them: Evidence of genetic selection against general intelligence and concurrent environmental enrichment in
vocabulary usage since the mid 19th century.” Frontiers in Psychology published: xx April 2015 doi: 10.3389/fpsyg.2015.00361
It has been theorized that declines in general intelligence (g) due to genetic selection
stemming from the inverse association between completed fertility and IQ and the Flynn effect co-occur, with the effects of the latter being concentrated on less heritable non-g sources of intelligence variance. Evidence for this comes from the observation that 19th century populations were more intellectually productive, and also exhibited faster simple reaction times than modern ones, suggesting greater information-processing ability and therefore higher g. This co-occurrence model is tested via examination of historical changes in the utilization frequencies of words from the highly g-loaded WORDSUM test across 5.9 million texts spanning the period 1850–2005. Consistent with predictions, words with higher difficulties (δ parameters from Item Response Theory) and stronger negative correlations between pass rates and completed fertility declined in use over time whereas less difficult and less strongly selected words, increased in use over time, consistent with a Flynn effect stemming in part from the vocabulary enriching effects of increases in population literacy. These findings persisted when explicitly controlled for word age, changing literacy rates and temporal autocorrelation. These trends constitute compelling evidence for the co-occurrence model.
The co-occurence model is the decidedly unsexy name given to the theory that Flynn effects and dysgenic effects co-occur. I call it “the leaky boats hypothesis” (Loehlin, 1997) : Flynn effect is the rising tide; Woodley effect the leaky boats.
In the West, up until the early to mid 19th century, those with high levels of socioeconomic status, wealth, and education (all of which are proxies for intelligence; Herrnstein and Murray, 1994) had higher numbers of surviving offspring relative to those with comparatively lower levels (Clark, 2007; Skirbekk, 2008), suggesting that higher intelligence may have conferred fitness advantages
on individuals having to cope with extremes of cold, disease outbreaks, and conflict (Woodley and Figueredo, 2013). Subsequent increases in global temperature, coinciding with the end of the Little Ice Age in the mid-19th century, reduced environmental harshness, boosting agricultural yields thus reducing ecological
stress and conflict (see: Zhang et al., 2007, 2011 for a demonstration of the inverse historical relationship between temperature and conflict). This would have substantially relaxed selection against those with lower intelligence (Woodley and Figueredo, 2013). This was coupled with advances in medicine (which would have included better means of fertility control, hygiene, nutrition, and medication; Lynn, 2011), and also social innovations such as welfare, mass schooling, and universal healthcare. The combined effect of these was a demographic transition characterized
by general reductions in fertility, which were most pronounced among those with higher intelligence (Lynn, 2011). This was mediated primarily by fertility control coupled with the increasing prevalence of opportunities to delay fertility (i.e., higher
education, increasing status competition, etc., which disproportionately attenuated the fertility of high-IQ.
As the authors say: More difficult words presented sharper historical declines in usage
over the 1850–2005 period, words for which pass rates are more negatively
associated with fertility are decreasing in usage over time, which is consistent with those being the more difficult words words that are both more difficult and for which pass rates are more negatively associated with fertility are decreasing over time.
It may be a minor matter, but I did my own little analysis, and find that word A is an outlier. It is very easy, and much more frequent than the other items: all the other words are rare by comparison. Every test needs to start with an easy item, but I wonder how much work this particular word does. However, even this very common word shows exactly the same trend as the other easy, but far less frequent words.
In sum, have Woodley et al. put another crucial piece into the dysgenic jigsaw? At the moment, it looks like it.
I sent the messenger boy off with his usual shilling, and noticed a certain impudence as he accepted it. Perhaps the under kitchen maid has been spreading false rumours about me, in her contumely way.