So both the students and the monkeys were shown a series of four photographs, and then after a pause of a few minutes a single photo appeared on the screen. The goal was to determine whether the photograph was, or was not, among the four shown earlier. But they could also select an icon on the screen that said they didn't know and wanted out of the trial.
"It's a well-known thing in us and primates that we remember well the first item on a list, and the last item, but we remember more dimly the items in the middle of the list," Smith says.
Rats Don’t Measure Up
Both the monkeys and the humans had the same problem with the middle pictures, and opted out of the experiment if they couldn't figure out if the photo was on the list or not. Thus both were expressing confusion, or uncertainty, in almost precisely the same way.
"The patterns of results produced by humans and animals provide some of the closest human-animal similarities in performance ever reported in the comparative literature," he says.
The dolphin performed a similar test, although since it wasn't trained to operate joysticks it was asked to signal whether a tone heard through an underwater speaker was above, or below, a certain frequency. The dolphin came up with the right answer quickly when the tone was clearly above or below the frequency, but when it was too close for the animal to tell, it opted out of the experiment, just like the monkeys and the undergraduates.
Smith suspects that the state of confusion is shared among other animals who are not as "cognitively sophisticated" as humans, monkeys and a bottlenose dolphin, but when the researchers tried to prove it with rats, they failed.
It could be that the test simply didn't work, or the researchers didn't try hard enough, he says. Or it could mean rats are never confused. They just blunder through life, making instantaneous decisions even if they don't know what's going on.
All this may not come as a surprise to many readers.
Just about everybody has had a pet at one time or another that clearly seemed confused, but Smith cautions against reading too much into that. Anecdotes are just stories, he says, not science.
Of course, that can't possibly include my border collie. Whenever he's confused he exhibits the same behavior. He heads for his food dish.
If I did that every time I couldn't figure something out, I'd probably gain about 500 pounds a day.
Lee Dye’s column appears weekly on ABCNEWS.com. A former science writer for the Los Angeles Times, he now lives in Juneau, Alaska.