Often neglected, vocabulary drives reading comprehension, study reports

iStock_000025474831XSmallVocabulary is once again being taken seriously in the classroom after a long period of neglect, says a recent study in Reading Research Quarterly. The renaissance of vocabulary is a very positive trend, the researchers write, because in ways that are not completely understood, vocabulary plays an important role in how skilled students will become as readers.

“Words may seem like simple entities, but they are not,” the authors write in their review of the literature on vocabulary and vocabulary assessment. “Their surface simplicity belies a deeper complexity.”

Close ties to comprehension

“There is no doubt that vocabulary is closely tied to comprehension. In study after study vocabulary knowledge predicts comprehension performance consistently with positive correlations typically between .6 and .8,” write P. David Pearson and Elfrieda Hiebert of the University of California, Berkeley and Michael Kamil of Stanford University.

Studies have failed to show that general vocabulary instruction is directly linked to improved performance on reading comprehension tests, the authors write, but students who learn vocabulary from specific texts do seem to perform better on reading comprehension tests on those specific texts, the authors note.

The researchers suggest that one reason studies have been unable to document the “far transfer” of vocabulary building on general reading comprehension is that current measures of vocabulary are simply too insensitive and undeveloped.

Vocabulary assessments have become increasingly contextualized in recent years, coming a long way from quizzing students on how well they have memorized lists of words and definitions, but there needs to be an even more sophisticated understanding and approach to vocabulary assessment, the authors say. More sensitive vocabulary assessments would help shed light on how vocabulary contributes to improved reading comprehension and also would help educators be more effective in how they teach vocabulary.

Theory of vocabulary assessment

There are 5 aspects of word knowledge that play into reading, according to research by W. E. Nagy and J. A. Scott:

1. Incrementality–Knowledge of a word becomes a little deeper and more precise each time a word is encountered; 2. Multidimensionality–Words such as glimpse and glance have different nuances of meaning; 3. Polyemy–Many words have multiple meanings and the more common the word, the more meanings it is likely to have; 4. Interrelatedness–Words are often associated with other words (e.g. dogs bark); 5. Heterogeneity–A word’s meaning differs depending on its function and structure; for example, a common word like run can have as many as 20 different meanings.

Meaning acquired incrementally

Two of the characteristics of word knowledge, incrementality and heterogeneity, have important implications for assessing vocabulary, the researchers write. The meaning of a word is seldom acquired in an all-or-nothing fashion but rather acquired incrementally.

Vocabulary assessment should try to measure students’ evolving understanding of the heterogenous meanings of words and of their nuances, the authors write. Repeating a word in assessments with different distractors and in different contexts tests students’ multilayered knowledge of that word.

“The assessment of students’ knowledge of word meanings, what we generally call vocabulary assessment, is as old as reading assessment itself,” the authors write. The earliest measures of vocabulary consisted of asking students to define or explain words, but beginning in the 1970s, vocabulary assessments have become more and more contextualized.

Authentic contexts

After reviewing 50 studies on vocabulary learning, the National Reading Panel in 2000 concluded that students acquire vocabulary best when it is used in meaningful, authentic contexts, and are less likely to remember words that are presented in decontextualized formats such as in lists, the researchers report.

Previous research by J. Read (2000) on vocabulary assessments for learners of English as a second language (ESL) identified three continua for designing and evaluating vocabulary assessments.

These three continua are: 1. Discrete-embedded–Is vocabulary tested separately or as part of text comprehension? 2. Selective-comprehensive–In word selection, are the vocabulary words a loose sample of words or representative of a larger corpus of words such as the 2,000 most frequently occurring words in the English language? 3.Contextualized-decontextualized–To what degree is context required to determine the meaning of a word?

Word selection

Word selection is an important consideration in both teaching and assessing vocabulary, the researchers write. In current large-scale vocabulary assessments, words are chosen on the basis of what words students at a particular grade level should know. But students’ prior knowledge of words is not necessarily the best construct for word selection, the authors write.

“For all intents and purposes, any word in the English language could be found on a typical vocabulary test, provided that it discriminates across students,” the authors write. “The question of interest is how could word choices be made in a more principled way.”

One approach to word selection described in previous research by I. L. Beck, the study says, is to view vocabulary as falling into three tiers:

  • The 1st tier comprises high-frequency words such as come, go, happy, that do not need to be taught, except to English-language learners.
  • The 2nd tier comprises words that mature language speakers use when they read and write; these are less common labels for common concepts such as stunning instead of pretty, astonished instead of surprised, etc.
  • The 3rd tier comprises rare words that are specific to certain domains such as chlorophyll, photosynthesis, etc.

The authors of the Reading Research Quarterly study note that one recommendation for vocabulary assessment would be to use only Tier 2 words.

Another researcher, A. Biemiller, has identified words that should be taught in the primary grades based on how likely students are to know these words at the end of each grade; he has also incorporated words from the Living Word Vocabulary, grade levels 2, 4 and 6 (Dale and O’Rourke 1981). With such a list of words, educators could, at any point in the school year, get students on track to learn the next set of words they are likely to need in their everyday reading.

“In this way,” the authors write, we could eliminate, or at least minimize, the vocabulary gap between various groups of students who, by virtue of differences in experience and instruction, differ markedly in their vocabulary knowledge.”

Semantic clusters

Another approach to word selection is the use of “semantic clusters”. Researchers have identified clusters, mini-clusters and super-clusters of words that have semantic associations. For example, the word plunge is part of a cluster of 19 words related to descending motion, but also part of a super-cluster of 321 words related to type of motion.

The National Assessment of Educational Progress (NAEP) recently signaled an important shift in vocabulary assessment, the authors write. “Vocabulary items will function both as a measure of passage comprehension and as a test of readers’ specific knowledge of the word’s meaning as intended by the passage author,” wrote the National Assessment Governing Board (NAGB), which sets policy for the NAEP.

The new emphasis is on understanding the meanings of words that writers use to convey information or meaning, not to measure readers’ ability to learn new terms or words.

The NAGB also takes a stand on what kind of vocabulary is worth assessing, the authors write. Words chosen for vocabulary instruction and assessment should be words that characterize the vocabulary of mature language users, words that label familiar and broadly understood concepts and that are found in grade-level material, the NAGB states.

The authors note that these criteria are similar to Beck’s criteria for tier-2 words. The NAGB also believes that distractors play an important role in assessing vocabulary as a facet of comprehension, the authors note.

Educators might better helping second-language learners with their reading problems if there was a greater understanding of the link between vocabulary and reading comprehension, the researchers write. It’s important to bear in mind that cultural knowledge also plays a role in the relationship between vocabulary and reading comprehension, the authors note.

The NAEP bears close watching because it may generate a new paradigm for conceptualizing and measuring vocabulary, the authors write. The first testing under this new paradigm is scheduled to occur in 2009.

Educators have learned to appreciate that reading is a highly complex process. The authors emphasize in this study that acquiring vocabulary also is a highly complex process and one that is intimately linked to reading comprehension.

“Vocabulary assessment: What we know and what we need to learn” by P. David Pearson, Elfrieda Hiebert and Michael Kamil, Reading Research Quarterly, April/May/June 2007, Volume 42, Number 2, pp. 282-296.

Published in ERN September 2007, Volume 20, Number 6

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