Instinct can make creatures make complex responses to stimuli. Compared with non-instinctive respond, instinctive respond requires only a few nerve cells. A brain with capabilities of non-instinctive respond must have a large number of nerve cells, and no insect brain has such a number of nerve cells.
The statement 'Creatures with brains larger than insect brains are capable of non-instinctive respond' can be inferred from the above.