“It’s about 100 kilometers…”
But then she stopped.
She looked embarrassed.
She said, “I know where it is. But I always get the words for ‘east’ and ‘west’ mixed up.”
The answer… interference theory!
Here’s how the writer described it:
“presenting semantically grouped L2 words to learners has a deleterious effect on learning.”
(Isn’t that lovely writing? Maybe he should try a spy novel next…)
And here’s how I would translate the writer’s description:
You learn two new words today. But because the words are similar (ex. east and west; push and pull) tomorrow and every other day for the rest of your life you mix up the two words. And that’s not good.

That’s a 35% difference!
Not bad…
And if you’d like to learn all my tips and tricks for building a powerful, strong and sexy English vocabulary, well, you can do that right here: