Chapter 7: Cognitive Intelligence and Thinking

Cognitive Intelligence and Thinking challenges the prevailing assumption that the left hemisphere is the seat of human intellect, arguing instead that the right hemisphere is the primary driver of genuine cognitive intelligence, particularly regarding the general intelligence factor (g),. The text distinguishes between crystallized intelligence (Gc), which relies on learned procedures, education, and cultural context, and fluid intelligence (Gf), the capacity for novel problem-solving and pattern recognition, demonstrating that fluid intelligence is strongly correlated with right hemisphere function and white matter integrity,. Neuroscientific evidence, including studies of brain lesions, reaction times, and color acuity, indicates that the right hemisphere is superior in integrating information and managing complex, non-routine tasks, whereas the left hemisphere functions more like an intermediary, executing serial procedures without true comprehension of meaning,. The discussion extends to the "Flynn effect"—the observed rise in IQ scores over the 20th century—and contrasts it with the more recent "reverse Flynn effect," which suggests a statistically significant decline in cognitive ability, particularly among the highest scorers and in right-hemisphere-dependent tasks like spatial rotation,. McGilchrist proposes that the initial rise in IQ scores may be largely attributed to "scientific spectacles," a cultural shift toward abstract, taxonomic categorization favored by the left hemisphere (e.g., classifying dogs and rabbits as mammals rather than functionally relating them), rather than an increase in functional real-world intelligence,. Furthermore, the chapter highlights worrying trends in educational outcomes, such as grade inflation masking a decline in mathematical mastery and Piagetian developmental stages, suggesting that a societal over-reliance on left-hemisphere modes of thinking is actively eroding our capacity for deep understanding, logical deduction, and creative insight,.