December 16, 2016

Can Dogs Recall Human Actions? Study Reveals Possible Episodic Memory in Dogs

A study recently published in Current Biology, finds that dogs may have episodic memory.
By Laurie Anne Walden, DVM, ELS
Dogs may have episodic memory, allowing them to recall actions that they witnessed incidentally without expecting that they would need to remember, say the authors of a study recently published in Current Biology.
 
“This is the first evidence of episodic-like memory of others’ actions in a non-human species, and it is the first report of this type of memory in dogs,” write the authors. In a news release, lead author Claudia Fugazza, PhD, of Eötvös Loránd University (Budapest, Hungary), said, “We suggest that dogs may provide a good model to study the complexity of episodic-like memory in a natural setting, especially because this species has the evolutionary and developmental advantage to live in human social groups.”
 
Episodic memory, a type of long-term memory, is the recollection of events that a person has experienced. (Other types of long-term memory are semantic memory, or knowledge of facts, and procedural memory, which includes learned skills and knowledge of cause and effect). Because episodic memory probably includes an element of self-awareness, it is difficult to know whether a nonhuman animal truly has this type of memory, say the authors. Therefore, they refer to this memory in dogs as “episodic-like” instead of “episodic.”
 
Episodic memory relies on incidental encoding, storing memories of events without actively trying to remember them (by comparison, intentional encoding is purposeful learning). The investigators devised a way to study incidental encoding in dogs by unexpectedly testing their memories of their owner’s actions. If the dogs had expected the tests, they would have been more likely to use intentional encoding to remember what their owners had done.
 
The investigators used 17 dogs previously trained by their owners in the “Do As I Do” technique, in which dogs learn to mimic specific object-related actions performed by their owners. For example, after an owner walks around a bucket and gives the “Do it” command, the dog walks around the bucket; after an owner touches an open umbrella with a hand and gives the command, the dog touches the umbrella with a front paw. The researchers used this test to obtain a baseline measure of each dog’s performance on an expected imitation test. Sixteen of 17 dogs correctly imitated their owners’ actions.
 
After the baseline test, the owners taught their dogs to lie down on a mat after witnessing the object-related action instead of mimicking it. Once the dogs had begun lying down spontaneously (without a command) after seeing the action, the investigators assumed that the dogs no longer expected the “Do it” command. In this way, the “Do it” command became an unexpected test.
 
In the experimental stage, each owner performed an object-related action. After waiting one minute, the owner gave the “Do it” command. Eleven of the 17 dogs correctly mimicked the action they had witnessed (a video demonstration is available here). The investigators also conducted this test with a one-hour wait, after which 6 of the 17 dogs correctly imitated the action.
 
The investigators suggest that because the one-minute and one-hour imitation tests were unexpected, the dogs that correctly mimicked their owners’ actions were using incidentally encoded information—possible evidence of episodic-like memory. They also note that the difference in performance between one minute and one hour is consistent with episodic memory, which is thought to decay more rapidly than other types of long-term memory.
 
The study does not necessarily prove that dogs have episodic (or episodic-like) memory, however. In an interview, Clive Wynn, PhD, of Arizona State University, pointed out that dogs previously trained in “Do As I Do” might be primed to pay extra attention to what their owners are doing, even if they do not expect to receive the “Do it” command.
 
“To our knowledge, this is the first time that a non-human species shows evidence of being able to recall complex events (i.e., others’ actions) without motor practicing on them during the retention interval,” write the investigators. They conclude that dogs could be a model for the study of episodic memory in nonhuman animals.
 
Two of the authors received funding from the MTA-ELTE Comparative Ethology Research Group. The Hungarian Scientific Research Fund provided study funding.
 
Dr. Laurie Anne Walden received her doctorate in veterinary medicine from North Carolina State University. After an internship in small animal medicine and surgery at Auburn University, she returned to North Carolina, where she has been in small animal primary care practice for over 20 years. Dr. Walden is also a board-certified editor in the life sciences and owner of Walden Medical Writing, LLC. She works as a full-time freelance medical writer and editor and continues to see patients a few days each month.
 

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