cognitive bias
It's human nature to have cognitive biases. These tendencies to think in certain ways or process information by filtering it through your personal preferences, beliefs and experiences are normal, but they can offer a skewed perspective.

"We all have these biases -- they are the lenses through which we process information and they are a necessary part of the information-selection process," says Mark Reinecke, professor and chief psychologist at Northwestern University and Northwestern Memorial Hospital in Chicago. Even physicians and mental health professionals have cognitive biases when making decisions for their own health and while treating patients.

Meanwhile, certain subtle mental biases can affect the health choices you make on a daily basis -- often without your realizing it. This can include everything from the dietary and physical activity choices you make to the screening tests you choose to the medications you take. Sometimes these biases are harmless while other times they could be problematic.

Here's a look at six common cognitive biases that can affect your health-related lifestyle choices, your behavior and your health-care decisions.

Confirmation Bias

This refers to a tendency to seek and remember information that confirms what you already know or that fits the behavior you already have -- and to discount information that doesn't jibe with that.

A 2014 study from Germany found that when people search the internet for information about the effectiveness of psychotherapy and pharmacotherapy in the treatment of depression, they tend to have a confirmation bias toward psychotherapy that guides their search. "Not all research on health habits is uniform so it's pretty easy for someone to find research that meshes with what they believe in," explains psychologist Alice Domar, executive director of the Domar Center for Mind/Body Health and senior staff psychologist at Beth Israel Deaconess Medical Center in Boston. If you enjoy drinking wine, for example, you might focus on the studies that suggest moderate drinking is beneficial for your heart and ignore the research linking alcohol consumption with an increased risk of breast cancer and other forms of cancer.

Hindsight Bias

It's a form of selective recall where you think "I knew this all along!" when you're diagnosed with a condition or you get bad news about your health, says psychologist Leslie Heinberg, section head of the department of psychiatry and psychology at the Cleveland Clinic. "It makes us feel like we're more in control, rather than having forces way beyond our control affecting us."

This type of bias stems from a combination of selectively recalling information or symptoms consistent with what you now know to be true, believing that the outcome or event was inevitable, and believing that you could foresee or predict what happened, according to 2012 research in Perspectives on Psychological Science. If you're diagnosed with anemia, for example, you might think, "I knew it" and attribute your months of low energy and fatigue to anemia. This is an example of erroneous thinking, notes Jessecae Marsh, an assistant professor of psychology at Lehigh University in Bethlehem, Pennsylvania, because "fatigue can be a sign of so many different things. A hindsight bias causes you to reinterpret your previous symptoms in light of the diagnosis."

Optimism Bias

"Maintaining an optimistic world view and a sense of efficacy is, in fact, quite helpful -- it protects you from anxiety and it means you're going to stay positive," Reinecke says. But it becomes maladaptive, he adds, if you convince yourself that you're never going to develop a certain health problem even if you engage in known risks. If you believe you look and feel better with a tan, you might continue spending long hours soaking up the sun, telling yourself you won't get skin cancer since you use sunscreen. Or you might continue smoking, convincing yourself that you won't get lung cancer because your great uncle Harold, a lifelong smoker, never did. It comes down to "overestimating a good outcome," Heinberg says.

Comment: It's been said before but it merits being said again: As long as you don't burn, sunlight is very good for you and smoking -- if you're the smoking type and choose natural tobacco -- can be good for you too. This author needs to examine her own biases!

In a 2013 study, researchers at Cornell University surveyed college students (who are known to have a substantial optimism bias) about their flu-prevention efforts and found that unrealistic optimists had significantly lower intentions to engage in smart hand-hygiene practices.

A close cousin to this bias is probability neglect -- where you ignore the inherent risks or the laws of probability of developing a particular disease because "you're certain you're going to be in the minority who don't get it," Heinberg says. This may be the case, for example, for a woman in her 40s or 50s who has never had a mammogram because breast cancer doesn't run in her family. "Most women who develop breast cancer don't have a family history," Heinberg says.

Comment: She did it again! The author is apparently unaware of the dangers of mammograms.

Status Quo Bias

Some people chafe at the prospect of change and want to stick with what they know and what's comfortable, even if it's not working that well -- a form of inertia that may be caused by a status quo bias. So you may be reluctant to change to a different health insurance plan or doctor because you're familiar with the one you have now, even if you're not pleased with how things are going.

"There's a lot to be said for being consistent with a health care provider because it leads to a therapeutic rapport, consistency in care and compliance," Reinecke says. "But it can lead you to stick with something even though it's not working." Case in point: You don't want to switch to a new medication your doctor suggests even though the one you're taking isn't helping. Indeed, in a 2013 study, researchers at Stanford University conducted a series of experiments where they gave people the option of reducing their anxiety while waiting for an electric shock to be administered or doing nothing (the default choice) while awaiting the shock; when doing nothing was the status-quo option, nearly 50 percent of the participants went that route. The inclination to stick with "the devil you know" is that strong.

Comment: The author does have a good point here. Some people choose their car mechanics with more care than they do their doctors. If your car continues to break down despite repeated 'fixings' you'd certainly find someone new to look under the hood.

Restraint Bias

If you tend to overestimate your level of self-control in the face of temptation, you're intimately familiar with this bias. You might go to a football game with friends and vow not to drink more than two beers but then you get caught up in the camaraderie and drink more. Or maybe you take your kids out for ice cream, telling yourself that you don't need to have it, but you blow your resolve when you get there. In a 2009 series of studies, researchers at Northwestern University found that people tend to overestimate their capacity for impulse control, which leads them to overexpose themselves to temptation, thus promoting impulsive behavior.

Generally speaking, "people think they have more self-control than they do," Domar says, "and people don't like to have limits placed on them." It's also easy for people to overlook "the influence of the environment and situational variables," Reinecke says. This is especially true with dieting and drinking behavior and among recovering smokers, experts say.

Standing Up to Your Own Biases

If you want to make better health-related decisions, the first step is to cultivate awareness of various cognitive biases you may have so that you "can guard against them," advises Jennifer Blumenthal-Barby, an associate professor of medical ethics at Baylor College of Medicine in Houston. "Patients can ask themselves: If the information were framed differently -- in terms of mortality [rates] instead of survival [rates] or absolute risk instead of relative risk reduction -- would I still feel the same way or make the same decision?"

It also helps to "look for evidence to support the opposite of what you're thinking," Marsh says. "Ask yourself: Am I considering other options, challenging my own beliefs or thinking through the probabilities?" Discussing these questions with people you trust can help. So can considering how your future self might feel about this decision, Blumenthal-Barby says, "since we know people have a present bias and tend to discount the future." To that end, you might ask yourself: Would my future self resent the choice I'm inclined to make right now?

Comment: This is a good argument for seeking out alternative therapies and practitioners vs continuing down the dead-end street of mainstream medicine.

Ultimately, "you need to have an openness to believing that you could be wrong or could be missing something important," Domar says. That's hard for a lot of people to do. But remember: "No one is too smart or too well-educated to fall into these traps," Heinberg says. "We're all vulnerable to this."