Hot brains. Researchers in Hong Kong compared teenagers on an attentional taks, and found that the variable that correlated best with whether they did well o rmore poorly was whether they owned a mobile phone. Phone users did better, whether their phones were switched on or not during testing. Previous studies had suggested that cognitive functions are enhanced with exposure to microwave radiation at wavelengths similar to that emitted by cellular phones. But was it their phone use per se that enhanced the performance on this task, or merely some other factor — probably demographic or socioeconomic — that correlates with phone ownership? It would be interesting to see if the degree of performance enhancement in a large sample population correlated with the length of ownership or volume of use — some variable that might get at accumulated lifetime microwave flux — of a cellular phone. New Scientist