Intelligence Quotient Points Research Articles

A long-term increase in the fluid intelligence of English children.

In the early decades of the century a number of geneticists and psychologists believed that intelligence in the economically advanced nations was in secular decline. Contrary to this expectation, recent data for a number of countries have shown that intelligence has been increasing at rates far greater than hitherto considered probable. A compilation of this data by Flynn for 14 economically advanced nations has shown that intelligence quotient (IQ) rises have generally been within the range of 2-12 IQ points per decade. These recent studies raise several questions, among which are precisely what abilities have been increasing over time; and whether existing data are correct in suggesting that the secular rise in Britain is lower than that in other countries. We report here that in English children there has been an increase over the past 50 years of 12.42 IQ points, averaging 2.48 points per decade. The increase has been in fluid intelligence, the mental power that underlies the acquisition of cognitive skills, rather than in crystallized intelligence, which represents the cognitive skills acquired in a particular culture.

Duration of circulatory arrest does influence the psychological development of children after cardiac operation in early life

Published works on intelligence quotient (IQ) and development following the use of profound hypothermia and circulatory arrest (TCA) to repair congenital heart defects in infants and young children suggest that little or no psychomotor impairment results. IQ scores derived from cognitive, memory, perceptual, quantitative, and verbal tests (McCarthy scale of the children's abilities, mean score 100, SD 16) were measured in 31 patients 5 years following operations performed with TCA between 1972 and 1976. These patients were compared with three control groups: (1) 19 patients with similar defects but operated upon using moderate hypothermia and continuous cardiopulmonary bypass (CPB); (2) 16 children who were the siblings of the TCA patients; and (3) 14 children who were the siblings of the CPB patients. The hypothermic temperatures reached were closely clustered around 15 degrees C in the TCA group and 28 degrees C in the CPB group. TCA time ranged from 22 to 71 minutes. Statistical analysis, which included, t test, chi square test of association, and Wilcoxon test, showed that the only baseline characteristic which differed between the two patient groups in respect to age at operation, age at testing, and preoperative physiological variables (level of cyanosis, weight, oxygen saturation, and hemoglobin concentration) was weight (p = 0.03). The mean score of the TCA group (91 +/- 4.0, SE) was significantly lower (p = 0.002) than that of their siblings (106 +/- 4.1, SE). The score for the CPB patients (102 +/- 5.2, SE) was not demonstrably different from that of their siblings (96 +/- 5.9, SE). The sibling and patient (TCA) IQ differences were associated with duration of arrest in verbal (p = 0.06), quantitative (p = 0.07), and general cognitive (p = 0.003) scores. A decrease of 0.53 point per minute of arrest time was estimated for the entire group of 31 patients; that is, in the 19 patients with siblings, for each minute increase in circulatory arrest time, the patients dropped 0.69 IQ point below their siblings. These results and analysis of other published data do not support the generally accepted view that TCA can be used entirely without penalty. We question the accepted "safe" limit of circulatory arrest of 60 minutes.