Erten and Tekin, "Effects on vocabulary acquisition of presenting new words in semantic sets versus semantically unrelated sets." (2007).
People have vocabulary organized in their minds in patterns or semantic sets. Semantic sets are word groups where the words have closely related meanings or share common elements. Students tend to "recall words on the basis of the semantic field in which they are conceptually mapped" (408). As a result, many language textbooks organize words into semantic sets. There is evidence, however, that this can interfere with students' learning of vocabulary.
For this study sixty fourth graders were taught eighty new vocabulary words. The fourth graders learned four sets of words: two groups of semantically unrelated vocabulary words and two groups of related words. The study indicates that students recalled semantically unrelated words more accurately and more quickly than semantically related words. This is because teaching vocabulary words that are too closely connected at the same time can "cause interference due to cross-association and may even hinder vocabulary learning" (407).
I connected to this article personally, because in high school my AP Spanish teacher taught us vocabulary using semantic sets. For example, she had us learn 30 vocabulary words for different types of fruits and vegetables in one week. To this day I cannot tell you how to say "olive" or "melon" in Spanish. Now I know that's because learning words that were too closely connected caused interference.
The text suggests that teachers organize instruction around a theme as opposed to semantic relationships. For example, "Sweater, changing room, try on, wool, striped" would be a better group of words to teach than "scarf, tie, coat, pants, and skirt" (409). I will definitely take this into consideration when I am teaching.