From 1889-2004, Western nations lost an average 14 IQ points (??)

From 1889-2004, Western nations lost an average 14 IQ points

Despite the fact that this study confirms many prejudices of older people, not to mention the movie Idiocracy, this finding is actually bizarrely inaccurate and contrary to hard empirical evidence. (Companies like Stanford-Binet have been testing people for decades.) Anybody familiar with the topic of IQ measurement knows of the Flynn Effect, which means in essence that IQ tests have to be renormed constantly because people keep getting higher and higher raw scores on them in each generation.

The Wikipedia summary of the subject states:

"Using the IQ values of today the average IQ of the U.S. in 1932, according to the first Stanford–Binet Intelligence Scales standardization sample, was 80.

IQ tests are updated periodically. For example, the Wechsler Intelligence Scale for Children (WISC), originally developed in 1949, was updated in 1974, in 1991, and again in 2003. The revised versions are standardized to 100 using new standardization samples. In ordinary use IQ tests are scored with respect to those standardization samples. The only way to compare the difficulty of two versions of a test is to conduct a study in which the same subjects take both versions. Doing so confirms IQ gains over time. The average rate of increase seems to be about three IQ points per decade in the U.S. on tests such as the WISC. The increasing raw scores appear on every major test, in every age range and in every modern industrialized country although not necessarily at the same rate as in the U.S. using the WISC. The increase has been continuous and roughly linear from the earliest days of testing to the present. Though the effect is most associated with IQ increases, a similar effect has been found with increases of semantic and episodic memory."

To place it in simple layman's terms:

Suppose you are a person of average intelligence, IQ 100 as measured against your peers by the original version of the Stanford-Binet test, and you could time-travel back to 1932. If you took the exact same S-B IQ test and gave the exact same answers, you would be considered quite gifted in their time, with an IQ in the 80th- or 90th-something percentile compared to the 1932 test-takers.

Yes, despite the evidence of Jersey Shore, human IQs have been increasing constantly, although the Flynn effect may now have slowed or ended in the majority populations of the most developed nations.

Does this mean actual intelligence is increasing? We don't know. Scientists agree on the facts, but disagree on their interpretation. We can say for sure that IQ test scores are increasing, but we don't know to what extent these scores really reflect intelligence, and there are many nuances to consider: nutrition, the overall improvement in test-taking skills, the living conditions of the specific socio-economic classes that have produced the bulk of the improvement, and so forth. The Wikipedia article linked above does a decent job of presenting all viewpoints.