Philosopher Fred Keijzer challenges this use of "Sphex", citing experiments in which behavioral adaptations are observed after many iterations. Keijzer sees the persistence of the "Sphex" example in cognitive theory as an indication of its rhetorical usefulness, not its factual accuracy. Of course, the repeated inspection of a disturbed nest may very well be an adaptive behavior, thus diminishing the aptness of Hofstadter's metaphor. As he concludes, "There is no reason for humans to remain stuck in an endless behavioral loop when wasps don’t."