Flynn Effect is actually causing an elevation of IQ's over time,
we might expect to see children begin reading and talkig earlier.
And there is evidence that this may be happening:
Of the 12 children in Leta Hollingsworth's, "Children Above 180 IQ", one of them, Child D, representing 8.33% of the total sample, began reading before 2. Six others, A, B, C, E, J, and K, or 50% of them, learned to read between 2 and 3. One, Child L, (8.33%) learned to read between 3 and 4. Two more , F and H (16.67%) were reading before 5, and one, Child G, (8.33%) began reading at 6. Child I's reading initiation date (8.33%) is unknown, but may also have started to read at 6. The average age at which reading began is about 3.67.
It's interesting to note that in the 1921 Terman Study, only 13% of the children with IQ's above 170 learned to read before they were 4, compared with 67% of Leta Hollingsworth's children with IQ's 10 or more points higher.
A similar study by Van Tassel and Baska found that 80% were reading before 5, and 55% were reading before 4.
In Mirica Gross' 1980's study of extremely gifted children in Australia, among the four children who scored at the 200 level on the 1973 edition of the Stanford Binet, Adrian was reading before 2, Christopher was reading between 2 and 3, Ian was reading before 2, and Hadley was reading at 18 months. Christopher and Ian scored exactly 200, while Adrian, at 6, scored 233. Dr. Gross' group learned to read at significantly earlier ages than any of the earlier groups, particularly when we consider that Dr. Gross' group consisted of children with ratio IQ's (on the Third Revision fo the Stanford Binet) of 160 and above. The average age at which they began to read was about 2.75.
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