Scientists at St Andrew's University School of Psychology and Neuroscience have revealed the scientific formula that, for the first time ever, defines precisely which human characteristics make a person "cute".

Professor David Perrett commissioned a panel of 90 adults to analyse 200 infant faces and rate their cuteness.

Custom software was then used to identify the features consistently prevalent in the 20 most and least cute faces.

This allowed Professor Perrett to define which characteristics contribute to cuteness.

The report, commissioned to mark the launch of Hallmark's brand new cute greetings card range, Little Meow, reveals the formula: Chubby cheeks + tiny chin + undersized nose + large eyes + rosy complexion = CUTE

When this cute formula is applied to images of both men and women, those facial features perceived as "cute" in infants - such as chubby cheeks and a button nose - also contribute to cuteness in adult faces.

Experiments conducted by Hallmark and the university also revealed that a subtle manipulation in face shape (a 20% application of the cute formula) was all that was needed to maximise cuteness in an adult face.

These subtle adaptations do not change adults into infants but instead involve the induction of features reminiscent of a younger appearance.

Prof Perrett said: "Cuteness can evoke both emotions of pleasure and care in humans, so we were keen to discover exactly what makes a person cute.

“By conducting the first comprehensive  scientific study of 'cuteness', that is, an exhaustive investigation into what is the ideal combination of features required to make a face 'cute' we were able to devise a precise formula for facial cuteness."