When the notebook user returned and searched for the item they had "lost", the dogs indicated the toy more often than the notebook or stapler.
Of the latter two items, the canines were just as likely to go for one as the other. Patrizia Piotti, lead researcher, of the University of Portsmouth said: "We assessed whether dogs would abandon an object that they find interesting in favour of an object useful for their human partner, a random novel distracter, or an empty container. Results showed that it was mainly self-interest that was driving the dogs' behaviour."
She added that, if there were no toys around, a different group of dogs were found to have better results. They looked at the spot where the notepad was hidden for half a second longer than the stapler.
However, this was only if the researcher was speaking to them in a high-pitched voice, suggesting the dogs were merely excited.
The research was published in the journal PLoS ONE.
Clive Wynne, at Arizona State University in Tempe, said: "Does the dog take an interest in an object that a human is interested in, or only in objects that dogs are interested in? "That got a clear-cut result: dogs only like objects that dogs like."