Posts tagged with information design

The classic red/green colouring scheme for trading screens seems too alarmist.

Conceptually, the red/green distinction makes sense as corresponding to stop/go in traffic signals. But traffic signals need to be neon and striking in a hectic 3-D environment where it’s paramount for everyone to definitely not-miss the stop command.

But in a sheltered 2-D environment where goals commonly include to master emotion, to control passive reactivity, to keep a long-term head in the middle of short-term volatility, and to digest (calmly) massive amounts of information en simultáneo, neon red/green seems too grating.

yellow and blue trading screen (GVZ)

I made the above picture with R of course, like this:

    reChart(up.col="light blue", dn.col="yellow")

(GVZ is the gold volatility index.)

It’s not a perfect colour scheme—I would use Lab to do better—but it already improves on #FF0000 versus #00FF00.


One theory of the evolution of trichromacy in primates says that

  • red/green dichotomy tells us whether meat or fruit is rotten or ripe (especially in dappled light)
  • blue/yellow dichotomy tells us how cool/warm something is
  • light/dark (value) is the most basic kind of vision.

If we take that as a starting point, a less alarmist colour scheme for trading software could use the blue/yellow dichotomy to indicate whether a security price went up or down. Use a neutral chroma for “small” moves (this depends upon one’s time-frame, but properly the definition of “big move” should be calibrated to an exponential moving average with some width depending on one’s market telescope). Intensity of the move could be signalled with lightness, so that most figures on a screen are a readable lightness of a neutral colour, but “big moves” are tinged with convexly more chroma and very-convexly more lightness.


The definition of “up/down” might be refigured as whether the trader is short/long the security in question, or perhaps redness/greenness could be used in conjunction with the “market view” of cold/hot, to indicate whether a security is moving for/against one’s strategy. That too could be seen as overly alarming, but a (pseudo)convex coding of red-ness might again solve the problem again, only invoking the “panic mode” when there’s really something to worry about.