May 21 (UPI) -- Ravens in a lab setting can experience negative emotional contagion, according to a new study by researchers in Austria.
Emotional contagion is said to occur when the emotional state of one individual effects the emotional state of another. The emotional state -- sadness or anger, for example -- can travel from one individual to the next. If one bird becomes depressed, the whole flock can soon be mopping around.
New experiments proved ravens in a laboratory setting can experience the social phenomenon.
"Scientific research on animal emotions is often received with skepticism," Jessie Adriaense, a cognitive biologist at the University of Vienna in Austria, said in a news release. "Research has advanced and we no longer follow the idea that emotions are less important than for example cognitive skills."
"Just like humans, animals are driven and motivated by their emotional states, which is reflected in their cognitive performance and behavioral expressions," Adriaense said. "Although it remains a challenging research endeavor, this study demonstrates we're heading in the right direction."
For the tests, researchers divided eight birds into four pairs and presented each twosome with a choice between two boxes, one empty and one hiding a hunk of cheese. Ravens like cheese.
After only a few repetitions, the ravens were able to figure out which box had the cheese in it. Once the ravens had figured out the test, researchers added a third box to the mix and observed the reactions of the two birds -- a so-called cognitive bias test. Scientists noted whether the ravens responded with optimism or pessimism.
Next, the pairs were separated and presented with a new choice: between carrots and dried dog food. Ravens don't like carrots. While one raven selected between two boxes, the other raven watched. The observer was only able to see the reaction of their former test partner, not the contents of the chosen box.
Finally, the ravens were presented the cognitive bias test again. Observers that watched a disappointed response were more likely to take their time and investigate the third box with apprehension. Ravens who witnessed normal behavior reacted normally to the third box.
The findings, published this week in the journal PNAS, suggest ravens can experience negative emotional contagion. Researchers suggest their unique study methods, which involved the integration of behavioral and psychological testing strategies, could be used to study other animals.
"Now that we know how it works, we can apply it to various animals," Adriaense said. "Getting to that stage was difficult, though, and we strongly profited from the interdisciplinary collaboration across faculties and research fields."