When apes make a bad decision or took a gamble that doesn't pay off, they bang on tables and perform other kinds of tantrum-like behaviors, often exhibiting regret by attempting to undo what they had done.
The new findings suggest that for apes, much like for people, the consequence of decisions cause emotions that, in turn, play a major role in shaping future decisions and the willingness to take risks.
"This suggests that the roots of human economic behavior are shared with these nonhumans," said Alexandra Rosati, an anthropologist at Yale University in New Haven, Conn. "One thing it might help explain is why humans show certain types of biases and why people don't seem to be very rational."
For most people, emotions influence both day-to-day behaviors and long-term decisions. Consider, for example, the choice between a sure-thing: $50, or the opportunity to take a gamble with a 50 percent chance of winning $100 and a 50 percent chance of getting nothing.
For some people, gambling and losing might cause enough disappointment and regret to affect their likelihood of gambling again in the future. People who respond less emotionally, on the other hand, might continue to gamble again and again.
To test the same kinds of reactions in animals, Rosati and colleagues trained chimpanzees and bonobos to perform two tasks.
In the first task, the apes had to decide between foods in two bowls. They could pick a mediocre item like peanuts, which taste OK but aren't anything special. Or they could gamble on a mystery bowl, which might yield an awesome treat like a banana or something like a cucumber, which is edible but, as Rosati said, "not awesome."
In the second task, the animals could choose between one piece of banana that they could have immediately or three pieces of banana if they were willing to wait a couple of minutes.