Here's an excerpt from the article which explains it further
When we are looking at charts and trading, esp. seasoned traders get an intuitive feeling of what may happen next. I have seen this with several traders. They see a pattern emerging and they know how its going to develop further. Obviously its not fool proof, but even if it's better than a coin toss probability, its good enough, in reality I have seen people who have a probability of getting it right more often. But then, it may not just be their refined visual perceptual abilities, there could be other variables that they may be tacitly processing, perhaps some moving averages or some other data. Its only when their brains kind of processes all these elements together that they get their predictions right.
Also, since price movements are fractal in nature, traders are further able to apply the same sense to different time frames, and perhaps benefit from larger swings as well.
But then how do we develop this intuition, unfortunately there are no shortcuts. Sufficient "Screen Time", "Focus" and "Reflection" seem to be the only ways get there.
BTW, if you are more interested in the subject of forecasting there is this awesome book by Philip E. Tetlock and Dan Gardner called "Superforecasting: The Art and Science of Prediction", here is a nice summary.