Much has been written of the pitfalls of being a helicopter parent, one who insulates children from adversity rather than encouraging their independence.
A new study from the University of Pennsylvania seems to back up this finding -- in dogs. Researchers showed that doting mothers seem to handicap their puppies, in this case reducing the likelihood of successfully completing a training program to become guide dogs.
The study was led by Emily Bray, who earned her Ph.D. in May from the Department of Psychology in Penn's School of Arts & Sciences. She collaborated with her advisors: Dorothy Cheney of the Department of Biology and Robert Seyfarth of the Department of Pscyhology in Arts & Sciences and James Serpell of the School of Veterinary Medicine. Mary Sammel, a professor of biostatistics in Penn's Perelman School of Medicine, was also a coauthor on the paper, published this week in Proceedings of the National Academy of Sciences. The research was conducted at The Seeing Eye, an organization in Morristown, N.J., that breeds, raises and trains dogs to guide blind people.
"It's remarkable," Bray said. "These puppies were with their mom for only five weeks and it's having an effect on their success two years later. It seems that puppies need to learn how to deal with small challenges at this early age and, if they don't, it hurts them later."
The study also found that dogs' cognition and temperament were associated with program success or failure, identifying specific tests that were predictive of the dogs' eventual performance. The results contribute to an understanding of the long-term effects of maternal style and suggest ways that guide-dog-training organizations might better identify dogs who are more likely to succeed.
Scientists have long been interested in the impact of early-life experiences on adult behavior, studying the phenomenon in rodents, primates and people. But hardly any studies had been done in dogs.
Guide dogs presented a useful group to study for several reasons. First, at The Seeing Eye, many puppies are raised in a single location under fairly controlled conditions. Second, the dogs have a clear measure of success: either they graduate from the program to become a working guide dog or they are released. And third, success as a guide dog isn't easy; the dog must be willing and able to navigate a complex and often-unpredictable environment while remaining obedient and attentive to its owner.
"This was a great way to conduct a controlled study where you can start to look at the contributing factors that make these dogs successful," Bray said. "And it was also exciting to be able to do this longitudinally, following them from puppyhood to their graduation or release from the training program."
The Seeing Eye was an enthusiastic partner in the research, cooperating with the Penn team to learn more about which factors influence the success of their puppies.
"Organizations like The Seeing Eye invest a huge amount in their training program but have about a 70 percent success rate," said Seyfarth. "That is good, but, from a practical point of view, they'd like to improve."
To gather information about the puppies' early-life experiences, Bray and a team of undergraduate research assistants essentially embedded themselves at The Seeing Eye's breeding facility, taking video and closely observing 23 mothers and their 98 puppies for their first five weeks of life.
"We wanted to know if we could differentiate the moms based on how they interacted with their puppies," Bray said. "We documented things like her nursing position, how much time she spent looking away from the puppies and how much time she spent in close proximity to her puppies or licking and grooming them."
A statistical analysis of all of this data revealed differences across the mothers, with some being particularly attentive and others less so. In a test of salivary cortisol levels, a measure of stress, the more vigilant mothers had higher baseline levels and higher spikes in cortisol when puppies were temporarily removed from them compared to those that were less vigilant.
When the researchers tracked the puppies a couple of years down the line, they found that those with mothers that were more attentive were less likely to graduate from The Seeing Eye's training program to become guide dogs. In particular, those dogs whose mothers nursed more often lying down, as opposed to sitting or standing up, were less likely to succeed.
"If a mother is lying on her stomach, the puppies basically have free access to milk, but, if the mother is standing up, then the puppies have to work to get it," Seyfarth said. "A hypothesis might be that you have to provide your offspring with minor obstacles that they can overcome for them to succeed later in life because, as we know, life as an adult involves obstacles."
The researchers conducted a second part of the study after the puppies had gone to live with foster families and then returned to The Seeing Eye for specific guide-dog training. The dogs, at this point young adults at 14 to 17 months old, were given tests to measure their cognition and temperament. A test of cognitive problem-solving skills, for example, involved a game with which the dog has to perform a multi-step task in order to reach a treat. Tests of temperament included observing the dogs' reactions, such as how long they took to bark to an umbrella being opened or to entering a room with a mechanical cat they'd never seen before.
"We saw that some dogs were calm and collected and solved problems quickly, while others were more reactive and perseverated at the problem-solving tasks," Bray said.
Perhaps unsurprisingly, dogs that did well at the problem-solving tasks and took longer to bark at novel objects were more likely to succeed in the guide-dog-training program.
In another study, published earlier this month in the journal Animal Cognition, the researchers reported that dogs' cognition and temperament were interrelated.
"People talk about them as though they're separate but we know that they're related," Bray said. "If you give an animal a puzzle box but they're so neophobic that they won't even approach it, they're not going to be able to solve it."
The work underscores the connection between maternal behavior and offsprings' behavior later in life, but further research is needed to tease out exactly why the attentive mothers were more likely to have puppies that were released from the program.
"It's hard to know whether the puppies are more anxious down the line because of the way that they've been coddled, if they've somehow picked up on their mother's anxiety," said Serpell, "or if they may have inherited some genetic component responsible for their behavior."
Bray is hoping to continue to explore these questions in her postdoctoral work at the University of Arizona and Canine Companions for Independence.
"With mothering, it seems like it's a delicate balance," she said. "It's easy to be like, 'Oh, smothering moms are the worst,' but we aren't exactly sure of the mechanisms yet and we don't want to tip too far in the other direction either."
The study was supported by the University of Pennsylvania and by National Science Foundation Grant 132185.
Proceedings of the National Academy of Sciences