Octopuses* and their cephalopod relatives are some of the smartest animals on the planet. Accordingly, many scientists want to understand how their mind works. To gain insights into the complex minds of cephalopods, researchers have been studying behavior in individual animals for years by presenting different animals with various visual stimuli. But many of the methods have downsides - for example, if you want to see how an octopus reacts to another octopus, you can add an octopus to the tank, but doing so introduces other variables. There may be variation in response based on how the introduced octopus looks, moves, etc, and these factors are hard to control. Ideally, you'd want something that you could repeat exactly every time - like a movie.
When researchers have tried in the past to use movies to stimulate behavioral responses, however, they found that the octopuses didn't respond. They weren't sure exactly why. Mirrors and pictures revealed that octopuses can clearly see the 2-D images, so that's not the issue. It was as if they just weren't interested in videos.
Dr. Renata Pronk and her colleagues from Macquarie University had a theory - they thought that the octopuses didn't believe them. Cephalopods rely heavily on their sight, and their vision is highly developed, so it's possible that the animals easily realized that poor quality videos weren't real life. If this were the case, Pronk realized, octpuses might respond to the breakthrough visuals of HDTV.
To test this hypothesis, she collected wild gloomy octopuses (Octopus tetricus) and subjected them to high-definition videos of things that might interest an octopus - a tasty crab, another octopus, or a jar to play with.
Incredibly, when she played the first video of a crab for her first test octopus, it grabbed at the screen. HDTV fooled it! Heres a video of a thoroughly-tricked octopus c/o New Scientist:
With their method working, the researchers tested 31 octopuses on 3 different days over a ten-day period to see if their behaviors varied temporally. Furthermore, they compared the individual animals, to look for evidence of personalities.
Behavioral biologists define a "personality" as behavioral differences between individuals that are consistent over time and across ecologically important contexts. In other words, Pronk wanted to know if some octopuses are consistently more aggressive or passive than others when exposed to the same situation.
The researchers found that the octopuses did react differently from each other, but they also reacted differently on different days. Some days they were highly reactive, other days they were less so. There was no consistent reaction from a given octopus.
These data suggest that octopuses have what is called "episodic personalities." This means that they do show differences in behavior between individuals, but they also show differences over time. This isn't necessarily "bad" or suggest they are "less intelligent." Indeed, this may be a sign of their intellect - after all, humans exhibit individual and temporal variation in behavioral response, too.
Moreover, this study gives biologists a new method to study octopus behavior. Of course, the most important questions have yet to be answered - like which American Idol contestant the octopuses will root for, or whether they will detest Jersey Shore as much as I do.
*Not Octopi. I was very disappointed to learn that it's not Octopi.
Pronk, R., Wilson, D., & Harcourt, R. (2010). Video playback demonstrates episodic personality in the gloomy octopus Journal of Experimental Biology, 213 (7), 1035-1041 DOI: 10.1242/jeb.040675
Monday, March 15, 2010