However; a study conducted by Dr. David Holzman of the University of Rochester in 1999 found that snakes' cognitive abilities (in specific regards to spatial learning) actually rival that of birds and rodents. Holzman challenged the typical testing method that was being used by biologists to examine snakes’ navigational abilities, claiming the structure of the arena itself was biologically in favor of rodents. He hypothesized that if the typical arena being used to test the animals was modified to cater to snake's innate biologically driven goals providing them with problem sets that they would likely encounter in their natural environment, this would give a more accurate view of their intelligence.