Tests of simple problem solving are important because they predict success in many real life activities, including education and work.  Often they are called tests of fluid intelligence.  Fluid intelligence is important in meeting many kinds of cognitive challenge, such as dealing with brain diseases, mental health conditions, or developmental or economic disadvantages.  Evidently a problem-solving test measures something important, but what is it?  We reasoned that, in all goal-directed behaviour, a complex problem must be split into a series of simpler, more focused parts.  If this fails, thought and behaviour lack a clear organization and structure.  To show the importance of mental segmentation, we presented standard tests of problem-solving already split into their parts.  We found that, when problems are split in advance, they become trivially easy.  The research confirms that, in standard tests of fluid intelligence, we are measuring the mind’s ability to organize a problem into separate, easily solved parts.  This ability is a core mental resource in dealing with many kinds of life challenge.

Duncan, J., Chylinski, D., Mitchell, D. J., & Bhandari, A. (2017).  Complexity and compositionality in fluid intelligence.  Proceedings of the National Academy of Sciences USA, 114, 5295-5299.