On "Steep" Learning Curves (Or: Hackling at Tilted Petards)
Okay, time to tilt against the windmills -- actually just one small, stupid windmill. But it's a windmill that particularly raises my hackles because it brings together my distaste for ignorant distortions of stock phrases with my interest in the history of psychology.
(You can bet that I double-checked the OED, after saying this, to confirm my use of "tilting" at windmills and raising "hackles". I don't want to be hoisted by my own petard. [Yep, double-checked that too.] Shouldn't we know what we are saying? -- what tilting and hackles and petards are?)
Here's a picture of a typical learning curve (from Stroop 1935):
(This curve charts the increasing speed with which subjects can name the colors of words on a list of color words printed in colors different from those named by the word [e.g., saying "blue" when seeing the word "red" printed in blue ink]. But the particular nature of the task is irrelevant to my point.)
Now consider this: If the curve were steeper, would that mean subjects were learning more quickly -- i.e., that the task was easier to learn -- or would it mean that the subjects were learning less quickly and the task was harder?
Next time you hear someone talk about a "steep learning curve" to mean the opposite of its proper meaning, tell her you're going to hackle her tilted petard!