The study at the University of Lincoln in UK studied whether youngsters can identify baby-like characteristics - a set of traits known as the 'baby schema' - across different species.
Researchers found that even pre-school children rate puppies, kittens and babies as cuter than their adult counterparts.
The discovery that young children are influenced by the baby schema - a round face, high forehead, big eyes and a small nose and mouth - is a significant step towards understanding why humans are more attracted to infantile features, researchers said.
"This study is important for several reasons. We already knew that adults experience this baby schema effect, finding babies with more infantile features cuter," said PhD student Marta Borgi.
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"Our results provide the first rigorous demonstration that a visual preference for these traits emerges very early during development.
"Independently of the species viewed, children in our study spent more time looking at images with a higher degree of these baby-like features.
"Interestingly, while participants gave different cuteness scores to dogs, cats and humans, they all found the images of adult dog faces cuter than both adult cats and human faces," Borgi said.
Pictures of human adults and babies, dogs, puppies, cats and kittens were digitally manipulated to appear 'cuter' by applying baby schema characteristics.
The same source images were also made less cute by giving the subjects more adult-like features: a narrow face, low forehead, small eyes, and large nose and mouth - making this study more rigorous than previous work.
"We have also demonstrated that children are highly attracted to dogs and puppies, and we now need to find out if that attractiveness may override children's ability to recognise stress signalling in dogs," said Professor Kerstin Meints, Professor in Developmental Psychology at Lincoln's School of Psychology, who supervised the research.
The research was published in the scientific journal Frontiers in Psychology.