Although the test subjects had similar baseline IQ scores -- a mean of 126, compared to the national average of 100 -- they showed a range of test performance results after the ranked group IQ tasks, revealing that some individuals' expressed IQ was affected by signals about their status within a small group.
The researchers wanted to know what was happening in the brain during the observed changes in IQ expression. The subjects were divided into two groups based on the results of their final rank -- the high performers, who scored above the median, and the low performers, who scored at or below the median. Two of every group of five subjects had their brains scanned using fMRI while they participated in the task.
Among the researchers' findings:
1. Dynamic responses occurred in multiple brain regions, especially the amygdala, the prefrontal cortex, and the nucleus accumbens -- regions believed to be involved in emotional processing, problem solving, and reward and pleasure, respectively.
2. All subjects had an initial increase in amygdala activation and diminished activity in the prefrontal cortex, both of which corresponded with a lower problem-solving ability.
3. By the end of the task, the high-performing group showed a decreased amygdala activation and an increased prefrontal cortex activation, both of which were associated with an increased ability to solve more difficult problems.
4. Positive changes in rank were associated with greater activity in the bilateral nucleus accumbens, which has traditionally been linked to learning and has been shown to respond to rewards and pleasure.
5. Negative changes in rank corresponded with greater activity in the dorsal anterior cingulate cortex, consistent with a response to conflicting information.
|Contact: Paula Byron|