Tortoises Can Master Mazes

Tortoises may be slow in a race, but not when it comes to thinking. “Generally people see reptiles as inert, stupid and unresponsive, I would like people to see that there is something much more complex going on.”1 says Dr. Anna Wilkinson, the University of Lincoln’s senior lecturer of animal cognition, and lead researcher of several studies investigating the mental capacities of red-footed tortoises. “Tortoises are perfect to study as they are considered largely unchanged from when they roamed the world millions of years ago. And this research is important so we can better understand the evolution of the brain and the evolution of cognition.”2

Dr. Wilkinson set out to test spatial cognition in reptiles3 with the help of her pet female red-footed tortoise, Moses. After setting up an eight-armed radial maze, complete with strawberry treats at the end of each arm and a black curtain obscuring the view outside the maze, Wilkinson and her colleagues put Moses to the test. They required the tortoise to get every strawberry piece without going back to any arm she had already visited. Moses performed well, using a strategy that was quite orderly and logical. Moses began to visit each arm in successive order, going to whichever one was next to the last she had visited.

To see if Moses would solve the maze differently when the environment was rich with cues, Dr. Wilkinson did another round of testing with the black curtain removed. Moses switched her strategy, transitioning to using the landmarks in the lab to tell which arms of the maze she had already been to and which she had not. “That requires quite a memory load because you have to remember where you’ve been.” said Dr. Wilkinson.

Though Moses’ landmark strategy has been observed in mammals, her response-based strategy has not.

training-turtles-617x416What makes these results especially impressive is the fact that tortoises do not have a hippocampus – the part of the brain that humans and other mammals use for memory, spatial navigation, and learning in general. So what part of their brains is at work during such tests? Something called the medial cortex, according to Dr. Wilkinson. This brain part is present in humans as well, and is linked to decision making and other complex cognition.4 Based on the fact that Moses’ response-based strategy has yet to be observed in mammals and birds, Wilkinson and her colleagues believe this means that the reptilian media cortex does not serve all of the same mechanisms as the hippocampus does.3

Red-footed tortoises also show signs of social learning. In a separate study,5 Dr. Wilkinson set up a barrier wire fence between the tortoises and a piece of strawberry. If the tortoises wanted to get the treat, they needed to walk around the fence. Unfortunately, none of the tortoises could figure this out on their own. After struggling for a while to get through the fence, they would give up. It never occurred to them that they could take the detour. However, when the tortoises observed a demonstrator tortoise going around the fence, they were able to replicate the behavior successfully in the next trial.

Additionally, the tortoises have demonstrated an ability for gaze following.6 This means that they will look in the same direction that another tortoise is looking, presumably to find out what has caught their attention. Such information can be highly valuable, as being alerted to the presence of food or predators by the gaze of another animal is critical for survival. Both of these findings suggest that red-footed tortoises are capable of social learning – something quite surprising considering that they typically live solitary lives.

Dr. Wilkinson continues to test tortoise cognition with the help of Moses and other red-footed tortoises. One of the most recent studies involves Moses deftly using a touch-screen tablet to receive food rewards.2

In the video below,7 science writer Emily Anthes discusses the research of Dr. Wilkinson, as well as studies focused on the cognition of other reptiles. She explains how scientists are proving that reptiles are more intelligent than previously thought, and even brings attention to the fact that flawed methods were used in past studies. Such methods include testing in cool laboratory environments. Since reptiles are cold-blooded and draw energy from external heat sources, those tested in cool temperatures would be sluggish and minimally responsive. When tested in warmer temperatures more suitable for reptiles, the animals performed far better.  Dr. Wilkinson tested her tortoises in environments of about 29 degrees Celsius (84 Fahrenheit), ensuring that they were fully alert. The video includes footage from Dr. Wilkinson’s maze study, and those of other scientists.

The maze paper’s abstract:

Much research has investigated spatial cognition in mammals and birds. Evidence suggests that the hippocampus plays a critical role in this; however, reptiles do not possess a hippocampus. It has been proposed that the reptilian medial cortex plays a similar role, yet little behavioral research has directly investigated this. Consequently, this study examined the role of extramaze cues in spatial navigation by the red-footed tortoise (Geochelone carbonaria) using an eight-arm radial maze. In Experiment 1 the maze was surrounded by a black curtain on which geometrical shapes were attached. After the tortoise reached above-chance performance we introduced test sessions in which the cues were removed. Performance was unaffected by cue removal. The tortoise appeared to have developed a “turn-by-one-arm” strategy. In a second experiment the curtain was removed and the tortoise was allowed access to a rich-cue environment. The use of the turn-by-one-arm strategy was significantly reduced and the tortoise appeared to be using the extramaze cues to navigate around the apparatus. This type of response-based strategy, and the specific contexts in which it was used, has not been observed in mammals and birds, suggesting that the mechanisms served by the reptilian medial cortex do not parallel exactly those of the hippocampus.

 

This article was written by Amanda Pachniewska, founder & editor of AnimalCognition.org


Sources

Photo credit: Mark Stevens, creative commons license – https://creativecommons.org/licenses/by-nc-sa/2.0/

1 – Laura Geggel
Tortoise Shows off Smarts by Mastering Touch-Screen Tech
LiveScience
http://www.livescience.com/47155-tortoise-touchscreen-learning.html

2 – Marie Daniels
Tortoises master touchscreen technology
University of Lincoln
http://www.lincoln.ac.uk/news/2014/08/935.asp

3 – Anna Wilkinson, et al.
Visual and response-based navigation in the tortoise (Geochelone carbonaria)
Animal Cognition
http://link.springer.com/article/10.1007%2Fs10071-009-0237-9

4 – Yang Y, Raine A
Prefrontal structural and functional brain imaging findings in antisocial, violent, and psychopathic individuals: a meta-analysis
Psychiatry Research
doi:10.1016/j.pscychresns.2009.03.012.

5 – Anna Wilkinson, et al.
Social learning in a non-social reptile (Geochelone carbonaria)
Biology Letters
http://rsbl.royalsocietypublishing.org/content/roybiolett/6/5/614.full.pdf

6 – Anna Wilkinson, et al.
Gaze following in the red-footed tortoise (Geochelone carbonaria).
Animal Cognition
http://pubget.com/paper/20411292/gaze-following-in-the-red-footed-tortoise-geochelone-carbonaria

7 – Emily Anthes
Coldblooded Does Not Mean Stupid
The New York Times
http://www.nytimes.com/2013/11/19/science/coldblooded-does-not-mean-stupid.html

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