Happy Fechner Day, Everyone!

fireworksToday, October 22, is Fechner Day. Finally! I thought it would never get here.

You might be wondering how you should celebrate.

What to wear? Are stone-washed jeans acceptable? What should you have for dinner? Can you safely serve filet mignon with Whoopie pie?

How should you greet friends and loved ones? "Frolic Freely For a Felicitous Fechner Fest!"? "Happy F-day!"?

Yes, without proper guidance, getting Fechner Day right can be challenging. This year, celebrate with confidence by remembering these 5 simple tips:


Tip 1: Don't confuse today with Festivus

Today is not the day to air grievances and tell others how they’ve disappointed you over the year. Nor is it the day to perform amazing feats of strength or gaze in admiration at unadorned aluminum poles.

Today is the day to honor the pioneering work of Dr. Gustav Fechner, a 19th century German scientist and philosopher.

tip 1


Tip 2: Stay in bed this morning

Ever notice how famous scientists often seem to achieve amazing breakthroughs while lying in bed?

The great French mathematician and philosopher Descartes stayed in bed until noon for most of his life. In fact, it was while lying in bed, watching a fly crawl on the ceiling, that he reportedly came up with the idea of the X-Y coordinate plane—the foundation for graphical analyses such as scatterplots.  (Which reminds me…did you know you can identify the exact X-Y coordinate of any location on a Minitab scatterplot while lying in bed? Simply hit your Snooze button, right-click the scale on the scatterplot, and select Crosshairs. Move the crosshairs to identify X-Y coordinates.)


(I also right-clicked the graph and changed the data symbols to resemble flies on a ceiling.)

But back to Fechner Day...

Today we commemorate the morning of October 22, 1850, when Gustav Fechner had his own "Aha!" moment while lying in bed. Suddenly, Fechner realized that there was a direct, quantitative relationship between the intensity of a physical stimulus and its perception by the human mind.


Tip 3: Hug a psychophysicist

Fechner's "Aha!" moment inspired him to conduct groundbreaking research in the field of psychophysics, which studies the relationship between physical stimulus and psychological perception. Today, over 150 years later, psychophysicists from all over the world continue to tease out the complex dynamics of the mind-body relationship.

So what better way to celebrate than to hug a psychophysicist today? If you have trouble finding one, this Minitab bar chart might help:


After you’ve hugged a psychophysicist, go ahead and hug a poet. Then, squeeze a philosopher—preferably a panpsychist. And while you’re at it, wrap your arms around  a medical doctor. Then hug a mathematician. Finally, embrace an aestheticist and cuddle a satirist.

Because Gustav Fechner was all of those things as well.


Tip 4: Obey Fechner's Law

Fechner's law defines how much sound, light, or other sensory stimulus must change before we can perceive a difference. According to the law, the subjective sensation of a stimulus is proportional to the logarithm of the stimulus intensity.

To show this relationship, I entered stimulus intensity levels in column C1 of a Minitab worksheet  and used the Minitab Calculator to assign the formula for Fechner's law to column C2.


Then I graphed the results on a Minitab scatterplot, using the annotation tools to highlight a change in stimulus intensity:


Here's how Fechner's law works. Suppose that you can just barely distinguish a difference in the brightness of two lights. You define that just-perceptible difference in perceived intensity as a 1-unit change on the Y scale (for example, a change from 2 to 3). According to Fechner's law, you would need a 12-unit change in physical intensity of the brightness of the lights to actually perceive the difference.

Fechner's law was an amazing breakthrough in its time. However, subsequent research has shown that it holds only over certain ranges of brightness, loudness, or sound. Today, researchers use many other functions to model this relationship between stimulus and perception.


Tip 5: Gawp at a good-looking rectangle

Fechner was intrigued by human aesthetics. In his classic study, he asked subjects to identify which of these rectangles they found the most aesthetically pleasing. Take a gander and decide for yourself:

rect 1 to 1rect 5 to 6

rect 4 to 5rect 3 to 4rect 20 to 29




rect 2 to 3

rect 21 to 34

rect 23 to 13rect 1 to 2rect 5 to 2




After you decide, hover your cursor over the rectangles to find the winner in Fechner's study. Fechner concluded that most people prefer the golden rectangle, whose width to height is the golden ratio. However, some consider this pure malarkey and have challenged the results (noting, for example, that the nonrandom order that Fechner presented the rectangles--in increasing ratios of width to length--biased his results).

So, over 150 years later, the jury is still out. But it's not just an abstract exercise in academics. 

Marketing analysts today still ponder whether the shape of a product package affects consumer buying preferences. For example, one recent exploratory study suggests that laundry detergent boxes that utilize proportions close to the golden ratio may have an edge over their less golden counterparts...

What do you think? Will you get more RSVPs to your Fechner Day party if your invitations are in the shape of a golden rectangle?

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