‘The Puss in Boots Effect:’ Women use infant-directed speech when addressing dogs with larger eyes

Is it love at first sight? Do you often speak in a high-pitched voice when looking into your furry friends’ big eyes? Well, there may be a reason for that.

New scientific research that explores communication between humans and animals has found that a woman’s vocal pitch increases when addressing dogs with larger eyes.

In a paper called “The Puss in Boots Effect: Dog Eye Size Influences Pet-directed Speech in Women,” researchers confirmed that pet-directed speech (PDS) is consistent with the way people speak to babies – this is known as infant-directed speech.

So, if you find yourself baby-talking your pets, it may be a sign of your love for those precious furballs due to their sweet infant-like eyes.

The study conducted by a group of scientists from the University of Lincoln, UK, the University of Sussex, the University of Saint-Etienne and the University of Arkansas at Little Rock in the US, noted that: “The retention of juvenile features in adult mammals, means dogs with larger eyes tend to elicit an increase in the pitch range of women’s voices.”

There are many reasons why people speak directly to their pets, this includes engaging the attention of dogs, fostering a social bond and “evoking caregiving behaviours in the owner,” the paper said.

In order to understand this better, the team of researchers conducted a speech test with 21 male and 24 female participants to assess the pitch used when addressing images of dogs whose eye size had been “manipulated” to increase or decrease from their breed baseline.

More than 400 people were also asked to rate the sex, age and cuteness of the images they had seen of these dogs in an online survey.

The results of the study confirmed that large eyes in dogs induced pet-directed speech in women but not men.

The female participants also rated dogs with a 30 per cent larger eye size as younger than dogs with apparently smaller eyes.

Holly Root-Gutteridge, a postdoctoral research fellow at the University of Lincoln, said the results show the way men respond “differently to cuteness”, even at an unconscious level, as men responded less to the changes in eye size than women.

“It also confirms that as humans, we do respond more to the perceived youthfulness of animals,” Dr Root-Gutteridge added.

Jemma Forman, a doctoral researcher at the University of Sussex, also discussed the “uncanny valley” effect and how if the eyes are too big, it can be quite unsettling for people.

The uncanny valley phenomenon can be described as an eerie feeling that some people get in response to not-quite-human figures. This may be a robot, for example, or maybe even computer-generated figures.

“Women increase the range of their voices when viewing bigger eye sizes. Conversely, when the eye size becomes too big and looks out-of-place, an ‘uncanny valley’ effect takes over in which the dogs become overall less pleasant and more unsettling to view,” Dr Forman said.

“Therefore, women speak with a less exaggerated vocal range to the dogs with large, uncanny eye sizes. This effect is more obvious in breeds such as the pug or Pomeranian, breeds of dog who already have relatively large eyes for their head size.”

Raffaela Lesch, assistant professor in zoology and bioacoustics at the University of Arkansas at Little Rock, said: “When analysing the acoustic data of all participants, it was impressive to discover how strongly certain participants modulated their voices.

“During interactions with dogs, we can’t really help it but use this very specific type of speech and it is very similar to the type of speech we use around little kids.”