"Long before it's in the papers"
January 28, 2015

RETURN TO THE WORLD SCIENCE HOME PAGE


Rats can reflect on their knowledge, study finds

March 8, 2007
Courtesy University of Georgia
and World Science staff

Let’s say a col­lege stu­dent en­ters a class­room to take a test. She prob­a­bly al­ready has an idea how she will do—knowl­edge avail­a­ble be­fore she ac­tu­al­ly takes out a pen­cil. But do an­i­mals have the same abil­i­ty to think about what they know or don’t know?

Courtesy University of Georgia


A new study has found that lab­o­ra­to­ry rats do. It’s the first to show that any non-pri­mate has this gift, and could lead to deep­er stud­ies on how an­i­mals and hu­mans think, the in­ves­ti­ga­tors said.

“This kind of re­search may change how we think about cog­ni­tion and mem­o­ry in an­i­mals,” said one of the sci­en­tists, psy­chol­o­gist Jo­n­a­thon Crys­tal of the Uni­ver­si­ty of Geor­gia in Ath­ens, Ga. The find­ings ap­pear in the cur­rent is­sue of the re­search jour­nal Cur­rent Bi­ol­o­gy.

Sci­en­tists have be­lieved for some time that peo­ple and non-hu­man pri­ma­tes are ca­pa­ble of “me­ta­cog­ni­tion”—rea­son­ing or think­ing about one’s own think­ing. 

Wheth­er oth­er an­i­mals do it has been un­clear. Bird stud­ies pro­duced in­con­clu­sive re­sults, ac­cord­ing to Crys­tal and his co-au­thor, Al­li­son Foote, a grad­uate stu­dent at the school. The pair called their work the first to find me­ta­cog­ni­tion in a non-primate, a pro­pos­al that may well be con­tro­ver­sial.

The ex­per­i­ments in­volved a “duration-dis­c­ri­mi­na­tion” test: of­fer­ing rats re­wards for clas­si­fy­ing a brief tone as ei­ther short or long. A right an­swer led to a large food re­ward; a wrong one, no prize. Al­so, on some tests runs, be­fore start­ing, the rats were giv­en a chance to back out of the test, in which case they got a small re­ward an­yway.

Some of the test choices were easy: the sig­nal lengths were very dif­fer­ent. Oth­er choices were hard, as the dif­fer­ence was smaller. In these cases the ro­dents faced a di­lem­ma: Should they take a chance on the test and risk no re­ward? Or should they bail out and take the small, but guar­an­teed prize?

If rats know wheth­er they know the an­swer, Crys­tal said, they’d pre­sum­a­bly de­cline most of­ten on harder tests. They would al­so per­form worst on hard tests that they’re not giv­en an op­tion to de­cline. “Our da­ta showed both to be true, sug­gest­ing the rats have knowl­edge of their own cog­ni­tive states.”

So “the rats know when they don’t know the an­swer,” and re­sponded ac­cord­ingly, said Crys­tal. The re­sults pre­s­ent a ro­dent mod­el that should al­low re­search­ers to un­der­stand bet­ter what an­i­mals are “cog­ni­tively so­phis­ti­cat­ed” and why, ac­cord­ing to the re­search­ers.

The re­search will al­so open new lines of in­quiry in­to the brain mech­a­nisms un­der­ly­ing this abil­i­ty, they added. Re­flect­ing on one’s own men­tal life is thought to be a de­fin­ing fea­ture of hu­mans, but the find­ing of metacog­ni­tion in rats would sug­gest this may be wide­spread among an­i­mals, the in­ves­ti­ga­tors spec­u­lat­ed. Does it mean, for ex­am­ple, that rats are “con­scious,” and could that al­so be true of oth­er non-pri­ma­tes? Fu­ture re­search could clar­i­fy that, Crys­tal and Foote said.


* * *

Send us a comment on this story, or send it to a friend

 

Sign up for
e-newsletter

   
 
subscribe
 
cancel

On Home Page         

LATEST

  • St­ar found to have lit­tle plan­ets over twice as old as our own

  • “Kind­ness curricu­lum” may bo­ost suc­cess in pre­schoolers

EXCLUSIVES

  • Smart­er mice with a “hum­anized” gene?

  • Was black­mail essen­tial for marr­iage to evolve?

  • Plu­to has even cold­er “twin” of sim­ilar size, studies find

  • Could simple an­ger have taught people to coop­erate?

MORE NEWS

  • F­rog said to de­scribe its home through song

  • Even r­ats will lend a help­ing paw: study

  • D­rug may undo aging-assoc­iated brain changes in ani­mals

Let’s say a college student enters a classroom to take a test. She probably already has an idea how she will do—knowledge available before she actually takes out a pencil. But do animals have the same ability to think about what they know or don’t know? A new study has found that laboratory rats do. It’s the first to show that any non-primate knows when it doesn’t know something, the invest igators said, and could lead to deeper studies about how animals and humans think. “This kind of research may change how we think about cognition and memory in animals,” said one of the scientists, psychologist Jonathon Crystal of the University of Georgia in Athens, Ga. The findings appear in the current issue of the research journal Current Biology. Scientists have believed for some time that people and non-human primates are capable of “metacognition”—reasoning or thinking about one’s own thinking. Whether other animals do it was unclear; studies on birds produced inconclusive results, according to Crystal and colleagues. They touted their work as the first to find metacognition in a non-primate, a proposal that may well be controversial. The experiments involved a “duration-discrimination” test: offering rats rewards for classifying a brief tone as either short or long. A right answer led to a large food reward; a wrong one, no prize. Also, on some tests runs, before starting, the rats were given a chance to decline the test completely, in which case they got a small reward anyway. Some of the test choices were easy: the signal lengths were very different. Other choices were hard, as the difference was smaller. In these cases the rodents faced a dilemma: Should they take a chance on the test with the risk of no reward? Or should they bail out and take the small, but guaranteed prize? If rats know whether they know the answer, Crystal said, they’d presumably decline most often on harder tests. They would also perform worst on hard tests that they’re not given an option to decline, he added. “Our data showed both to be true, suggesting the rats have knowledge of their own cognitive states.” So “the rats know when they don’t know the answer,” and responded accordingly, said Crystal. The results present a rodent model that should allow researchers to understand better what animals are “cognitively sophisticated” and why, according to the researchers. The research will also open new lines of inquiry into the brain mechanisms underlying this ability, they added. Reflecting on one’s own mental life is thought to be a defining feature of humans, but the finding of metacognition in rats would suggest this may be widespread among animals, the invest igators speculated. Does it mean, for example, that rats are “conscious,” and could that also be true of other non-primates? Future research could clarify that, according to Crystal and colleagues.