Animals with largest brain volume, have superior cognitive powers, shows a large-scale investigation into the evolution of self-control in animals.
According to psychologist Lucia Jacobs from University of California Berkeley,"The study levels the playing field on the question of animal intelligence," Science Daily reported.
The findings challenge prevailing assumptions that "relative" brain size is a more accurate predictor of intelligence than "absolute" brain size.
In one experiment, creatures large and small were tested to see if they would advance toward a clear cylinder visibly containing food - showing a lack of self-restraint - after they had been trained to access the food through a side opening in an opaque cylinder.
Smaller-brained animals did so with mixed results, said the study.