As much as we love the movie, nobody wants to worry about a snakes-on-a-plane scenario in the real world. But what can be said about dogs, pigs, or peacocks on a plane?

These are just a few of the "emotional support animals" that people have tried to bring on board in recent years. As the name suggests, these animals are meant to help their owners reduce psychological distress. But the scientific evidence to support this, for the most, remains unclear.

For starters, most studies in this area involve dogs — the most common support animals along with cats — which raises questions about all the other species people consider. Even in this existing research, it has been hard to reach a definite conclusion since there are so many variables tied to our emotional well-being.

"Isolating the effect of a pet in the context of all the other factors that influence a person’s mental health is so hard, so the evidence there is really, really mixed," said Molly Crossman, a psychology researcher at Yale.

This distinguishes emotional support animals from service animals, which are specifically trained to offer assistance to people with disabilities. For example, a service dog may be necessary to help a blind person walk to various places. But an emotional support dog is not trained to perform any specific tasks.

There are concerns over people possibly taking advantage of this to travel with animals on board for free, even though they do not have a crucial need for the presence of the animal.

“There has been a rise in the availability of false emotional support animal credentials online, enabling people who are not truly in need of animal assistance to abuse the rules and evade airline policies on animals in the cabin,” said Airlines for America earlier this year.

Of course, research has shown that some people may experience mental benefits from pet ownership. But simply owning a pet is different from needing a psychologist to certify an animal for therapeutic purposes, presenting an ethical dilemma.

Writing for the Conversation, Christine Calder of Mississippi State University also draws attention to how the animals may ultimately bear most of the emotional stress and suffering.

"Riding on planes, being in closed-in spaces, and being exposed to loud noises and crowds of people can be overstimulating and scary to an animal, especially one not accustomed to that particular environment," she states.

Psychologists also express doubts about the long-term effects even if the animal does offer some comfort in the short run.

With anxiety sufferers, for instance, Crossman explains that patients have to face their fears and learn to normalize situations that make them anxious. If one is only able to overcome various situations because of their emotional support beagle or tabby cat, it may risk creating an unhealthy dependency.