Oh Be A Fine Girl, Kiss Me Now

December 31st, 2011

This odd sentence is actually a mnemonic for stellar spectral types. Those spectral types, from hottest to coldest, are O, B, A, F, G, K, M, and N. But it’s easy to forget the order, so generations of astronomy students have learned the mnemonic above to keep them straight.

Here are some other science mnemonics, some courtesy of xkcd comics:

The order of categories in biological taxonomy (Kingdom, Phylum, Class, Order, Family, Genus, Species). “King Philip came over for good sex.”

The planets (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Nepture): “My very excellent mother just served us nachos.”

Priority order of operator execution in computer arithmetic expressions (Parentheses, exponentiation, division & multiplication, addition & subtraction): “Please excuse my dear Aunt Sally.”

SI prefixes for large numbers (kilo, mega, giga, tera, peta, exa, zetta) “Karl Marx gave the proletariat eleven zeppelins.”
SI prefixes for small numbers (milli, micro, nano, pico, femto, atto, zepto): “Microsoft made no profit from anyone’s Zunes.”

My point here concerns an oddity: these things work. It really is easier to memorize “Oh, be a fine girl, kiss me now” than to memorize OBAFGKMN. Pause for a moment to consider this. In strict information theory terms, the mnemonic should be harder to memorize than the simple string of letters. Thus, the ease of using mnemonics seems counterintuitive. What’s going on here?

The answer, I think, arises from a point I have made elsewhere: the fundamental data structure inside the human mind is the story. From what we know of dreams, we can be certain that they are not stories, yet everybody experiences dreams as stories. Like a Rorschach blot, when given random information, we organize it into a story, because our minds are organized to perceive the universe as a collection of stories. The letters OBAFGKMN are a random string of information that doesn’t fit into our minds well. But when we convert them into a story, we obtain a data structure compatible with our mental structures, and we can remember it well.

This, by the way, debunks the notion that “The Memory Palace” is the best way to organize one’s memories. Spatial memory is fairly good in the male brain, but not so good for females. But storytelling memory is the same for both genders.

The fact that mnemonics rely on stories, not spatial structures, strongly suggests that storytelling memory is superior to spatial memory. But let’s put it to a test. This test is rather unfair, I admit, because it relies on memorizing a string of digits, and storytelling memory works best with strings of alphabetic characters. But let’s set up the following conversion table:

0: Zero C (because Z is so rare)
1: One O
2: Two T
3: Three R
4: Four F
5: Five I
6: Six S
7 Seven V
8 Eight E
9 Nine N

Next, let’s convert the value of pi into this format:


Here’s my stab at making a story out of this: “Robert offered Fred oil in narrow toys secreted inside really intense English nannies. Virgin needles ran through Robert’s eye.”

Question: which is harder to memorize: the number or the story?