Јака студија, мајсторе. Уште да ја прочиташе. Ајде, чекор по чекор, да ги потенцираме најбитните елементи од студијата што ја прати, а ги имаш у заклучок.
Differences in cognitive abilities are correlated with differences in brain size, and both brain size and cogntive ability are correlated with age, sex, social class, and race. As noted earlier, correlation does not prove cause and effect, but, just as zero correlations provide no support for a hypothesis of cause and effect, non-zero correlations do provide support. We are convinced that the brain-size/cognitive-ability correlations that we have reported are, in fact, due to cause and effect. This is because we are unaware of any variable, other than the
brain, that can directly mediate cognitive ability. Some have suggested that perhaps increased intellectual activity and/or improved nutrition cause higher cognitive ability. But, just as physical activity and/or better nutrition can only increase physical strength via their effects on muscles, increased cognitive "strength" can occur only via increased brain function. Of course, brain size is not the only mediator of brain function; Miller's (1994) review suggests that amount of brain myelination is related to IQ (as in work by Schultz, 1991; Willerman, Schultz, Rutledge, & Bigler, 1994).
Nonetheless, we believe that the important research questions are as follows:
(1) What is responsible for these group differences
in brain size; that is, are they genetically and/or environmentally caused? and
(2) Why does variation in brain size correlate with differences in cognitive ability?
Numerous problem areas remain to be researched.
For example, it is not known whether women have fewer neurons than do men; there may be greater cortical packing density in women, and thus, it is myelin thickness or some other variable that is responsible for the sex differences in brain size (Haug, 1987).
In a postmortem study of brain tissue from the temporal lobes of 5 women and 4 men, Witelson, Glezer, and Kigar (1995) supported the hypothesis that women's neurons are packed more tightly. It is unknown, however, whether tightly packed neurons are more or less efficient than are those that are more. widely spaced; the latter may allow a greater number of
synaptic connections.
Serious paradoxes also require resolution.
For example, White women have brain sizes equal to or smaller than those of Black men, but nonetheless score higher than do Black men in general cognitive ability.
Additional research with magnetic resonance imaging or behavior genetic techniques is certain to enrich knowledge of these important relationships. MRI may identify features of the brain that correlate even more highly with IQ than does volume (some possibilities are
neuronal density, white/gray contrast, ventricle/brain ratio, and various specific brain regions). More generally, as Broca and other nineteenth-century scientists conjectured so long ago, it may be the complexities of the convolutions of the brain, and the varieties and efficiencies of its commissures, rather than its actual size, that is related to intellectual ability and that differentiates populations.
Што значи ова, Ванлок? Какви заклучоци можеш да повлечеш од потенцираните делови од текстот?