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Bill Gibson is the skeptical, hard-nosed research psychologist who inhabited the office next to me until he retired recently. One afternoon I asked him about the faded photograph of a dog he kept on his desk. Bill is a math guy, a left-brainer. He designs computer systems that can look at your eyeballs and tell which part of your cortex is working overtime. But when he started telling me about Blue, a Shepherd-Husky mix, he melted. For eleven years, Blue was Bill’s best friend. “Blue would look me straight in the eye. He knew things.” Bill said.

Then he told me how Blue came down with cancer of the bowel. “I was with him at the end,” Bill said. “I put him on a nice blanket and gave him a kiss goodbye and talked to him. I had him cremated. I kept the ashes for a while and then later on I spread them on a mountain. I was a mess for a long time. Sometimes I would break into tears. It was embarrassing.”

Then Bill started to choke up. “I still think about him every day. I loved him more than I’ve loved any person in the world. I’ll probably think of him on my death bed.”

Bill is not unusual in the he experienced after his dog's death. But even though 90% of dog and cat owners think of their members of the family, our society does not generally acknowledge the profound grief that can follow the loss of a pet. For deeply attached pet owners, however, researchers have found the experiences of losing a pet and a family member are quite similar (here).

The Evolution of Grief: The Reunion Theory

Grief can knock you flat. But does it have an evolutionary function? The late John Bowlby, a British psychiatrist, thought so, as does the evolutionary psychologist John Archer. They argued that grief did NOT originally evolve as an emotional response to the death of a loved one. They think the original function of grief was to motivate searching behavior for living companions that have gone AWOL, for example, because of a relationship breakup or a forced separation. This idea is called the reunion theory. It holds that grief motivates searching behaviors that could help us locate and ultimately reunite with a lost partner. According to the reunion theory, the grief we experience when a human companion actually dies is an evolutionary side-effect of the search-promotion function of grief.

I admit that the reunion theory of the evolution of grief sounds far-fetched. However, Claire White of California State University at Northridge and Dan Fessler of UCLA have developed a comprehensive account of grief that includes elements of the reunion theory (here). They also came up with an innovative way to test their ideas. They reasoned that if grief evolved to motive attempts to locate missing loved ones, grieving people would be hypervigilant in their quest to find lost partners. That is, they would be prone to mistaking unrelated sights and sounds for their missing companions. White and Fessler call these perceptual errors “false recognitions.” False recognitions are not . Rather, they are misperceptions of real external stimuli such as a stranger who, at a distance, resembles the missing loved one.

Based on the reunion theory, they made the following predictions about false recognitions of grieving individuals:

Bereaved people who are more attached to their lost companions will be more prone to hypervigilance and hence be more likely to experience false recognitions.

Bereaved people who frequently view photographs of lost companions will commit more false recognitions.

As time since the loss passes, false recognitions of bereaved people will become less frequent.

Here is the best part of the study. White and Fessler tested their ideas by examining false recognitions in pet owners whose dogs or cats had recently died.

Studying False Recognitions of Dead Pets

The participants were recruited through online pet loss websites and flyers placed in veterinary hospitals in Los Angeles and Belfast. To participate, the subjects had to have owned a dog or cat for at least six years, and the animal had to have died within the previous two years. The final sample included 107 bereaved dog owners and 57 cat owners.

The participants took an online survey that included:

A standardized 23-item index of how much people loved their pets.

A measure of how frequently they viewed photographs of their dead pet.

The False Recognition Questionnaire. This scale contained six items related to the frequency that the subjects had, in the last two weeks, had false recognition experiences (for example, hearing or seeing their dead pet.

The Results: Perceiving Dead Pets Is A Common Phenomenon

Within the previous 14 days, the vast majority of the bereaved pet owners had false recognition experiences.

84% had, for at least a split second, believed they had seen or heard their dead pet.

93% found pet-related habits hard to break (e. ., they had begun to feed the dead pet or call its name).

70% had mistaken a sound for their dead pet.

77% had mistaken another animal for their dead pet.

32% had felt the urge to look for their dead pet.

21% said they sometimes felt an image of the pet so strong that they felt the animals were alive.

All three of the researchers’ main hypotheses were supported. Individuals who were very attached to their pets were more likely to have frequent false pet recognition experiences. Subjects who frequently viewed photographs of their pet had higher scores on the False Recognition Questionnaire. And the frequency of false pet recognition experiences declined a time passed since their pet’s death.

The Bottom Line

As is always the case, there are limitations to this research. For example, the subjects were self-selected on the basis of their grief for a deceased pet. Because they were highly attached to their animals, it is unclear how often false recognitions occur among typical pet owners.

That said, I love this study. To my surprise, it provided limited support for the reunion theory of grief. (I say limited because the correlations between the measures tended to be the low range.) More importantly, these findings suggest that weird mistakes when it comes to seeing, hearing, or even trying to feed an animal that you know is dead is not a sign of incipient . Indeed these experiences may turn out to be common.

Finally, this study exemplifies how research on our relationships with animals can offer insights into many aspects of human psychology. As my friend and fellow Psychology Today blogger Marc Bekoff put it, “I like studying human-animal interactions because they reveal so much about ourselves.”

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