When you’re an eye doctor, and I’ve spent my entire career as one, you learn a lot about how people use, and misuse, the sense of sight to perceive the world around them. As humans, we’re constantly interpreting and occasionally manipulating our experiences to distinguish fantasy from reality. Some people are better at this than others. Some, for example, are consistently taken in by conspiracy theories or fake news stories, whereas others can quickly sniff them out as bogus.

A few years ago, I asked myself-what’s the difference between people with keen powers of perception and those with weaker powers? Is it education? Experience? Genetics? I began researching the topic and discovered there isn’t even a term to classify our power of perception, so I adopted one. I call it perceptual intelligence, and it’s the title of my new book.

“Perceptual Intelligence,” (or PI), is our ability to interpret sensory data and arrive at a decision. Just as with other forms of intelligence, some people have higher PI than others. Good decision-makers exhibit a high level of Perceptual Intelligence, whereas bad decision-makers demonstrate weaker PI.

PI, I learned, is an acquired skill. We can improve our PI, in fact, through awareness and practice. You may, for instance, find yourself overreacting to certain situations or circumstances. But with proper knowledge and a different perspective, you can train yourself to arrive at a more appropriate reaction.

In this fast-paced digital age, we’re forced to make decisions on the fly and often “leap before we look.” That might mean handing over your credit card number without verifying a website’s security, or trusting a news story without considering the integrity of the source. People with high PI, however, consistently “look before they leap.” Before making a decision, they ask themselves, instinctively: Am I interpreting this sensory data correctly and making the best choice?

Every millisecond, our senses take in a massive amount of information, which then travels to the brain. The brain, in turn, is where our perceptions originate. Those perceptions may accurately reflect reality but may also derail us toward fantasy. The driving question behind my book is: Why do our perceptions sometimes clash with reality? There are many reasons, I discovered.

One is medical. For example, a condition known as synesthesia can cause a person to literally see music or taste sounds. (A second form of synesthesia connects objects such as letters and numbers with a sensory perception such as color or taste.) Even the common cold, which affects the eyes, ears, nose, and throat—not to mention the brain, when our heads fill with congestion—has been known to distort our power of perception. When we are under the weather from the flu, our power of perception might seem so foggy that we develop a pessimistic view of situations that we might otherwise view with optimism. Another medical factor influencing perception is sleep deprivation. As any insomniac or parent of a newborn will tell you, a lack of sleep can distort our perception of the world, sometimes even fogging our memory of what happened during our sleepless state.

An obvious (and sometimes deadly) influence on our power of perception is drugs and alcohol. We don’t need to review criminal cases and “beer goggle” studies to see how drugs and alcohol impair our senses and affect our judgment.

There’s also our psychology, biology, genetics, habits, cultural upbringing, and memories, all of which combine to create our unique perceptual filter, influencing our decisions, thoughts and beliefs. The pope’s belief in life after death, for example, is diametrically opposed to the views of theoretical physicist Lawrence Krauss. Yet each is convinced that his take on death is the correct one. Is the pope blinded by faith? Is Dr. Krauss opposed to any idea that isn’t evidence-based? We all create our own unique version of the world, shaped by our own perceptions.

Often, our perceptions work behind the scenes, shaping our thoughts and behaviors without us even realizing. When we have a vague memory of a painful incident, what purpose does it serve? Why do we hold onto an incorrect and hurtful perception when instead we could find a positive use for it? People with finely-tuned PI can identify and topple faulty ideas that try to sabotage them.

PI can be improved, like any other skill, such as driving a car, playing a sport, or learning an instrument; and doing so can have a profound effect on your life. Boosting your “BS Detector” can lead to better decision-making, reduce the risk of financial, health, and family problems, even increase your overall happiness.