NASHVILLE, Oct. 1 (UPI) -- A U.S. study of cockroaches suggests the insects are morning morons, but evening geniuses.
Vanderbilt University researchers have discovered dramatic daily variations in the cockroach's learning ability.
"This is the first example of an insect whose ability to learn is controlled by its biological clock," said Professor of biological sciences Terry Page, who led the study with undergraduate students Susan Decker and Shannon McConnaughey.
The researchers taught individual cockroaches to associate peppermint -- a scent they normally find slightly distasteful -- with sugar water, causing them to favor it over vanilla, a scent they find universally appealing.
The researchers trained individual cockroaches at different times and found those trained during the evening or at night retained the memory for several days. During the morning, however, when cockroaches are least active, they were totally incapable of forming a new memory, although they could recall memories learned at other times.
"It is very surprising that the deficit in the morning is so profound," said Page. "An interesting question is why the animal would not want to learn at that particular time of day. We have no idea."
