A person with a severe and obvious mental illness walks into a crowded room. Let us call her Sara. People notice. Some are frightened. They watch her closely. They stare in disbelief at odd behaviours, mimicking awkward mannerisms, ridiculing speech and actions that do not fit in. This is stigma, and we have all seen it happen.

And then Mark walks into the room. He suffers silently with severe emotional distress. He hides it well. He does not want others to know about his psychological condition, the medication he takes, or the psychotherapy sessions he attends. He has experienced harsh judgment, disdain and rejection too many times. This is stigma, and we have all seen this happen too.

In addition to being stigmatised, people like Sara and Mark are being blamed for gun violence. Yet, they are not the problem. This dangerous stereotype is being actively perpetuated by high-level politicians. From President Barak Obama to Republican Senator Lindsey Graham, a false connection is being made between mental health problems and gun violence.

Current efforts to alter the national background check system are directed at restricting gun ownership for people who have a mental disorder. This approach will have little or no impact as studies show that people with mental illnesses are involved in 4 percent of violent crimes and are 11 times as likely as the general population to be the victims of violent crime. When people with mental illness are dangerous, it is most often directed at themselves.

Approximately 25 percent of American adults - half of them women and half of them men - suffer from a mental disorder. The Centers for Disease Control and Prevention (CDC) report that the majority of adults with diagnosable mental disorders don't receive treatment, even though psychotherapy and medication are effective in 80-90 percent of individuals.

Far too often, people with mental disorders are treated abysmally. Active discrimination is common. People with severe mental illness are denied employment, housing and health care, in spite of legal protections intended by the Americans with Disabilities Act, the Fair Housing Act, and the United Nations Declaration on the Rights of People with a Disability.

In the aftermath of violent massacres in Newtown, Connecticut, Aurora, Colorado, and Tucson, Arizona, considerable media and legislative attention have been paid to issues of gun control and the underfunded mental health care system. The National Rifle Association and its political supporters have recently begun advocating for increased mental health services in lieu of tightening gun control laws.

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In Connecticut, a bipartisan legislative panel is considering improvements in psychiatric and psychological intervention, including increased case management, training for educators and intervention by physicians. The Colorado legislature is debating stricter mental health procedures for involuntary hospitalisations and mandatory notifications regarding gun ownership.

For many, the power of the stigma outweighs the need for mental health services, no matter how great that need may be or how good the mental health care system is. The CDC's Office of Minority Health and Health Disparities reports that 78 percent of adults with mental health symptoms believe that treatment would help them to lead normal lives. However, a person with unmet mental health needs will very often refuse to use these services - no matter how effective or well-intentioned - as long as the stigma is present.

While the media portray wildly popular stories with likeable characters who have different kinds of mental illness, such as in Silver Linings Playbook, House, Homeland, and Sherlock, these fictional creations are intended strictly for entertainment purposes, and do not represent the actual day-to-day negative experience of those with mental illness.

Stigma is not only experienced by individuals with mental illness. Stigma is contagious and it spreads. Families of persons with mental illness are stigmatised. Institutions providing mental health services are viewed with suspicion and avoided. Many people who take medications do not disclose this information to their closest friends for fear of negative judgment.

Tighter gun control restrictions might help with gun violence in general, but these restrictions will not help people with mental illness. Public panic that arises following mass shootings might stir up wrong-headed fears that link violence to mental illness, but these fears - and the associated stigma - will not help people with mental illness. Even increased mental health services are not likely to help people with mental illness, if stigma keeps them away from these services.

I hope that one day Sara and Mark will be able to walk into a room and no one is frightened. No one wants to make fun of them. No one wants to flee. My hope is that Sara and Mark will be seen simply as people. My hope is that everyone in the room has compassion for our shared human condition.

Dr Linda Rubin is a licensed psychologist and professor in the Counselling Psychology doctoral programme at Texas Woman's University. She has teaching, clinical and research expertise in interpersonal violence, traumatic stress and gender issues, with 85 publications and professional presentations in international, national and regional venues.

Follow her on Twitter: @DrLindaRubin