Complex sentence: In an experiment, 17 people who had received three months of intensive training in meditation and 23 meditation novices, to perform an attention task in which they had to successively pick out two numbers embedded in a series of letters.
Split into simpler sentences: In an experiment, 17 people received three months of intensive training in meditation. Those 17 along with 23 meditation novices performed an attention task in which they successively picked out two numbers embedded in a series of letters.