Intuition

February 1991, the Persian Gulf. Lieutenant Commander Michael Riley, aboard HMS Gloucester, looked at his radar screen and saw a dot moving out from the coast. He gave the order to fire before he could explain why.

This might sound ordinary. The Gulf was in the middle of the war with Iraq, and missiles flying back and forth must have seemed almost routine.

But it was not ordinary at all that Riley could tell the dot was a missile. That same path was also the flight path of friendly A-6 aircraft. They came home from their missions along that line all the time. An emergency order to fire on that dot could have meant killing his own side.

Asked how he knew, Riley could only say that it seemed to be accelerating. And here is the strange part. Riley said he knew within the first 3 seconds. But at that radar’s rate, 3 seconds was only 2 sweeps. He had seen the dot just twice.

How can two dots tell you something is accelerating? You need at least three. And when the tapes were checked afterwards, there was no acceleration at all.

So was Riley just lucky?

Two dots, the same speed

Look at the two radar scopes below. The left one shows the A-6. The right one shows a Silkworm missile. Both leave the coast at the same point, at the same speed, about 620 knots. The only difference is altitude.

Step through it and you will see the A-6 appear on the second sweep, not far from the coast. The Silkworm is not there yet. It shows up on the third sweep, farther out than the operators were used to.

The crew of the Gloucester had watched A-6s come home like this many times. Their brains had learned, without being told, that “the first dot appears one sweep after the coast.” When the Silkworm’s dot appeared farther out than that, the brain concluded it must be moving very fast.

On the next sweep, the dot moves the normal distance for something flying at about 600 knots. Next to that first, apparently huge jump, it looks as if the target burst off the coast very fast and then slowed down. That is the “acceleration” Riley felt.

The altitude the radar could not see

The Type 992 radar on the Gloucester gave only bearing and range. It did not measure altitude. But near the coast, the land reflects radar energy back as noise, called ground clutter. Anything flying low stays buried in that noise for longer.

The A-6 flew at about 3,000 feet, so it left the clutter quickly. The Silkworm flew low, at about 1,000 feet, so it stayed hidden for more than one sweep. The range at which the first dot appeared was an indirect signal of altitude.

The radar did not measure altitude. Riley’s brain read it anyway.

Knowing without knowing that you know

Gary Klein, a psychologist who studies how people make decisions under pressure, heard this story from Riley himself. At the time, Riley still could not explain how he knew. Klein’s team went through the radar recordings sweep by sweep, until Ellis, one of the team, noticed the link between altitude and clutter. When they told Riley the hypothesis, he agreed it was probably the answer.

Think about how strange that is. The information that let him make the right call in a few seconds was in Riley’s head all along, but he could not reach it. The only thing that made it up to conscious awareness was a short label, “it’s accelerating,” and a cold feeling that said: this one is not ours.

This is what intuition looks like. It is not magic, and it is not a random guess. It is hundreds of past experiences compressed until only a feeling is left. The brain catches the anomaly before language can catch up. And sometimes it gives the anomaly the wrong name, the way Riley called altitude acceleration.

Intuition looks like a sixth sense. It may actually be full of reasons.