My idea is that native speakers understand the feelings of words, which is different from definitions of words. And feelings can be learned by using the senses to make more than images. Images with feeling, sound, movement etc. For example the word "excitement" is a hot active word, but the word "happy" is maybe warm, moving, but slower than excited. This idea comes from NLP, neurology, and psycholinguistics.
If the group is very advanced I could introduce some tough technical vocabulary, but the important point is learning to feel the difference between words and nuance.Instead of image training I could say coaching for communication.