Whose Brain Works Harder? (adapted from Malley-Morrison & Yap, 2001) To reinforce the textbook's emphasis on scientific versus common sense approaches to knowledge, and to illustrate one of the approaches to measuring brain function, which of these individuals is likely to have the hardest working brains-those who do well on tests of abstract thinking or those who do not do well. Share your response after reading the following. Although it might seem as if abstract thinking would require hard work on the part of brains, it turns out that men who do well on such tests do not show as high a level of brain effort as those who do not. Using positron emission tomography (PET) scans, Haier et al. (1988) found that the brains of people scoring high on a test of abstract reasoning used less energy in the process than those with low scores. Specifically, Haier and his associates injected glucose tracer into the bloodstreams of eight male volunteers who took the abstract reasoning test. The basis of PET scan technology is that in brain areas undergoing high activity, the glucose tracer is taken up in greater quantities, thus giving greater brightness to that area of the PET scan. In Haier et al.'s experiment, part of the left rear cerebral cortex lit up on the PET scans in all eight volunteers, confirming that this area is involved in abstract thought. However, the scans of those who did not perform well showed more diffuse activity throughout the entire brain, as though the participants were struggling to solve the problem everywhere in their brains at once. Haier and his associates suggested that on some tasks, individuals with higher cognitive ability might have more efficient neural circuits, allowing their brains to perform well at lower metabolic rates.