Psychologists have long struggled to define intelligence, and there are doubts regarding the accuracy of tests designed to measure it. The widely accepted notion that higher intelligence is associated with faster information processing, or “mental speed,” is now being challenged by a new study conducted in Germany.
Published in the journal Nature Communications, the study indicates that individuals with higher intelligence scores take longer to solve complex problems due to their tendency to avoid hasty conclusions. The research also reveals a link between problem-solving abilities and differences in brain connectivity and synchrony among different regions.
The study, led by Michael Schirner of the Charité-Universitätsmedizin Berlin, analyzed data from 1,176 participants in the Human Connectome Project. The researchers examined the relationship between intelligence scores and reaction times on the Penn Matrix Reasoning Test, which involves increasingly complex pattern-matching tasks. The findings showed that individuals with higher intelligence scores solved easier problems more quickly, but took more time to solve difficult ones, likely because they dedicated more time to inferring hidden rules before arriving at the correct solution.
To further investigate, the researchers created personalized brain network models for 650 participants by combining their brain connectivity data with general models of neural circuits related to decision-making and working memory. The analysis revealed that those who took longer to solve complex tasks exhibited higher resting state connectivity between the frontal and parietal lobes and greater synchrony between these brain regions.
The frontal lobe is known for its role in attention and decision-making, while the parietal lobe collects and integrates sensory information. Previous brain scanning studies have indicated that intelligence involves a frontoparietal network, so the increased synchrony between these regions may reflect a prefrontal attentional mechanism that influences processing in the parietal lobe.
Contrary to the assumption that higher intelligence results from a faster brain, these findings challenge this notion. They suggest that speed is not always advantageous and that there can be a tradeoff between speed and accuracy, leading to better decision-making. While quick and automatic thinking may suffice for easy tasks, a slower and more deliberate cognitive approach, which allows for thorough integration of relevant information, may be more effective for solving complex problems.