About 18 months ago, my one-year-old wasn’t well. Doctors had been telling us for a fortnight that it was just flu and it would pass. But that morning, I could feel something was terribly wrong.

So I picked her up, put her in the car and rushed her to the local emergency room. The medical staff thought I was overreacting.

“We just have to give this time,” they told me, yet again.

On that occasion, though, I could feel a sense of panic rising inside me, and I ignored all suggestions of overreaction. Sometimes you just know things aren’t right; you feel it in the pit of your stomach, your heart starts to race and you have a growing sense of unease.

I insisted - some would say I created quite a scene - that they admit her there and then.

They finally agreed. She was taken in, and within five minutes her heart rate had spiked dangerously and she had gone into septic shock. I still have nightmares about what might have happened.

This is called “maternal intuition”. If you are a parent or carer, you are probably familiar with this feeling of when something just doesn’t seem right. It might seem like an instinct - and it is often called so - but it is most likely an accumulation of experience that we have of our own children and the little signs and cues that we notice because we know them so well. Our response might seem like a spur-of-the-moment decision, without rational thought, but it isn’t.

When the doctors and nurses refused to take my “maternal intuition” seriously, they were most likely acting on their implicit bias, which is that parents, especially mothers, can become hysterical when it comes to their children’s health. There is research to show that health professionals are less likely to take women and girls seriously, and their pain and illnesses are often not tackled immediately.

Data also shows that people from minority-ethnic communities face prejudice and bias from healthcare professionals and are less likely to be diagnosed correctly or prescribed treatment.

So a combination of these biases likely played a role in why it took so long for our daughter to be diagnosed, why our concerns were ignored for so long and why I was perceived as a “hysterical parent”. The doctors’ and nurses’ instincts told them that nothing was wrong, even when it was.

You would think that people in such roles, where it can be a matter of life and death, would not act on instincts. Yet they do. Also, when people are stressed, tired and overworked, they are more likely to fall back on their instincts.

It’s something that teachers - who are charged with making thousands of decisions every day and are among the most stressed professionals, according to multiple surveys - need to be wary of, too.

So below, in an extract from my new book Sway: unravelling unconscious bias, I outline what gut instinct is and the dangers we need to recognise (see box, below, for more information on the book).

Our gut instinct is formed from something psychologists call “visual matching”. When a person sees a situation in front of them, they quickly match it to a sea of past experiences stored in a mental knowledge bank and then, based on a match, they assign meaning to the information in front of them. The brain then sends a signal to the gut, which is full of nerve cells.

Gut instinct can be very useful when making quick decisions in everyday life. Psychologist Antoine Bechara, at the University of Southern California, studied brain-damaged patients who could not formulate intuitions while making decisions. They had to decide purely via rational, logical reasoning.

“They ended up doing such a complicated analysis, factoring everything in, that it could take them hours to decide between two kinds of cereal,” Bechara says.

Our gut instinct allows us to expedite this process. Our instincts help us to assess people and situations quickly, determine whether or not we can trust them, and make timely decisions. In this way, they are essential for our survival.

The bad news is that in this process, we also form biases that cloud our instincts. Our unconscious biases change how our instincts react to certain situations, and the way we perceive others, and can compel us to choose one object or person favourably over another.

For example, we might impose personality traits on people that make it easier for us to process information about them in the future, or mistakenly compare them with someone else because of our confirmation biases and erroneous memories.

Social norms also underlie our gut instinct about people. Our default bias is associated with these social norms. Often bias is created when a particular object or person does not meet the normative standards in society, and our instinct is to view them with suspicion and to alienate or stigmatise them.

Do you remember watching that viral video in which Robert Kelly, an associate professor of international relations at Pusan National University in South Korea, was being interviewed live on the BBC when his two children wandered in, and a woman of East Asian racial heritage frantically tried to remove them?

An anonymous survey I conducted via social media forums revealed that more than 70 per cent of people - most of whom claimed to be liberal, open-minded and non-prejudiced - immediately assumed that she was a nanny.

This prompts concerns regarding the racial biases inherent in our society about people of certain ethnic origins being assumed to be in subservient roles as helpers or assistants. It also raises questions about the perception of mixed-race couples, with people naturally assuming that we mate with people who are the same as us.

You might also remember the contentious comments made by Tim Hunt, a Nobel laureate, that sparked a fierce response across social media. In a speech delivered at a lunch for female journalists and scientists, entitled “Creative science - only a game”, he said: “Let me tell you about my trouble with girls … Three things happen when they are in the lab … You fall in love with them, they fall in love with you and when you criticise them, they cry.”

More recently, in August 2019, the chef Marco Pierre White told the Irish Independent that “the real positive with men [in the kitchen] is that men can absorb pressure better, that’s the main difference, because they are not as emotional.”

In both the above cases, these people’s biases and preconceptions are highly likely to affect their instincts about certain candidates in the lab or in the kitchen, and influence the hiring decisions they make.

In schools, such biases could also lead to instinctual decisions being made about colleagues or pupils - be it in academic or pastoral terms - that are based on intuition, not evidence.

John Nash was a Nobel prizewinning mathematician, and the film A Beautiful Mind was based on his life. He proposed a model for how actions and reactions around a norm operate in a micro-macro feedback loop.

In this case, a norm gives a person a rule of thumb for how they should behave and gives an expectation of how other people act in a given situation (macro). A person acts in the best way possible given the expectation (micro).

For a stable norm, people’s actions and behaviours remain the same without change, which is termed the micro-macro feedback loop. Our instinct is to resort to the normative default.

Our instincts about and against people are also formed due to association and affiliation. Skin colour is often one of the first cues for assigning group memberships and we all do this, no matter how much we deny it.

In 1968, the day after the assassination of Martin Luther King, Jane Elliott, an educator and antiracist activist, decided to address the problems of racial prejudice by dividing her third-grade class into groups on the basis of eye colour. All her students were white, and none of them could relate to the feeling of being a black person in America, so she wanted them to understand what discrimination felt like.

As seen in the PBS Frontline documentary A Class Divided, Elliott showed how easy it was to turn her seven-year-old pupils into hatemongers by making the blue-eyed children the targets of discrimination by the “better” brown-eyed children. After dividing the children, she told them that people with brown eyes were smarter, faster and better than those with blue eyes, as intelligence was linked to how much melanin we have. She also gave the brown-eyed children longer lunch breaks and other privileges.

Soon, the brown-eyed children became more confident and condescending towards their classmates, calling them “stupid” and shunning them in the playground. The blue-eyed children became meek and withdrawn.

This exercise, although controversial, is considered a landmark in showing how environmental cues can shape our biases and reinforce our in-group memberships. It confirmed that prejudice against members of the out group is learned in children. However, if it is not addressed and unlearned, we can carry these biases throughout our lives.

So when it comes to making important decisions about people or situations, we cannot always rely on instinct. Our instinct is a result of an accumulated knowledge and so its value cannot be discounted, especially when making quick decisions. But it is also shaped by our biases and prejudices, and so cannot be comparable to acting with complete rationality in accordance with evidence.

The key for us all is to not fall back on instinct for decision making but rather to use it as a trigger for sparking analytical and logical thought. It is vital to filter possibilities quickly at a subconscious level and direct our decision making to a point at which our rational, conscious mind can take over, one where we can acknowledge and evaluate our biases openly.

Friedrich Nietzsche, in his book The Birth of Tragedy, saw an enduring Apollonian and Dionysian dichotomy in human behaviour. One god, Apollo, stands for logic and reason while the other, Dionysus, stands for chaos. The Apollonian rational thinking is balanced by Dionysian instinct. There is a place for both.

Pragya Agarwal is a behavioural scientist and writer. This article is based on an extract from her book Sway: unravelling unconscious bias

This article originally appeared in the 10 July 2020 issue under the headline “Basic instinct”