Abstract
Hadley, E. B., Dickinson, D. K., Hirsh-Pasek, K., Colinkoff, R. M., & Nesbitt, K. T. (2016). Examining the acquisition of vocabulary knowledge depth among preschool students. Reading Research Quarterly, 51, 181–198.
Vocabulary knowledge is closely linked to reading comprehension (Quinn, Wagner, Petscher, & Lopez, 2015; Vellutino, Tunmer, Jaccard, & Chen, 2007). Typically, children’s vocabulary knowledge has been evaluated in terms of breadth or words that they recognize. However, there is a growing awareness that vocabulary knowledge is a complex construct that cannot be understood solely in terms of breadth, or number of words known (Christ, 2011). Vocabulary breadth is a descriptor of the overall number of entries in a learner’s lexicon, each of which may be known to a greater or lesser extent. Vocabulary depth is a descriptor of how well the individual entries in one’s lexicon are known (Anderson & Freebody, 1981). Depth can be defined as a learner’s richness of knowledge about individual words. However, depth has been less frequently explored than breadth in the literature, with many vocabulary intervention studies focusing on number of words learned, without asking how much and what kind of knowledge students have gained about individual words, or whether this knowledge is of sufficiently high quality to impact reading comprehension. This article focuses on two key aspects of depth: richness of semantic representation of words and knowledge of use in typical contexts.
Acquiring Deep Word Knowledge
Children can learn a few aspects of a word after only a few incidental exposures. They can make an association between an object and a word label and acquire limited information about the context in which the new word is encountered. Children may identify a picture of the word on a receptive vocabulary measure but lack a deeper understanding of the word’s nuances and uses in multiple contexts. Therefore, although children may, in a superficial sense, know the word, their semantic knowledge may not be extensive enough for them to use the word in real-world settings or draw on it when comprehending text. Encountering a word in multiple, varied contexts, such as in a book-reading session and then during a guided play activity, may facilitate deeper word knowledge than learning a word in a single context (Bolger, Balass, Landen, & Perfetti, 2008).
Deep Word Knowledge and Reading Comprehension
Networks of knowledge associated with words are a key factor in the relationship between vocabulary knowledge and reading comprehension. A person can understand what is read not only because he or she knows individual word meanings but also because he or she has built extensive networks of conceptual knowledge from which to draw on, of which vocabulary is the tip of the iceberg. To improve reading comprehension, therefore, vocabulary instruction must build deep, conceptually rich knowledge. As a learner has more experience with a word in a variety of contexts (Bolger et al., 2008), its phonological representation becomes more stable, more grammatical classes and inflections of the word are learned, and the meaning becomes incrementally more precise and less bound to context. High-quality representations, or semantic networks in which elements of form and meaning are tightly connected with one another, can be quickly retrieved, whereas low-quality representations threaten a reader’s retrieval speed and ability to comprehend a passage.
Weakness in semantic knowledge is due to a lack of relevant experience with words, such as repeated exposures to words’ phonological and semantic features. Limited experiences with words lead to weak semantic representations, which then lead to poor reading comprehension (Landi & Perfetti, 2007). Students who struggle are rated by teachers as more likely to be off task during class reading activities and less likely to read independently on their own (Morgan, Fuchs, Compton, Cordray, & Fuchs, 2008). This lack of sufficient exposure to print then limits students’ ability to build high-quality representations of words, which continues the cycle. Efforts to foster young children’s vocabulary learning, therefore, should focus not only on adding new words to their lexicons but also on building rich, high-quality representations of words. As learners add new words to their lexicons, their networks of word knowledge become more refined and precise for distinguishing new entries from old ones (Carey, 1978), thereby increasing depth, and when learners gain rich knowledge about a number of aspects of a word, they likely learn other, related words along the way, thereby increasing breadth.
Semantic Networks by Word Type
Depth of word knowledge can be conceptualized as a rich network of semantic associations around a word that support semantic processing and reading comprehension. The content of these networks, however, is thought to vary by form class (Miller & Fellbaum, 1991), which may also have consequences for how well different words are learned. Maguire, Hirsh-Pasek, and Golinkoff (2006) suggested that all words lie on a continuum of concepts and that words are easier or more difficult to learn based not on their form class but on how perceptually accessible they are, as determined by the following factors:
Shape: extent to which an object or action has a reliable outline or contour (Maguire et al., 2006);
Individuation: ease with which an item can be distinguished from others in a scene (Gentner & Boroditsky, 2001);
Concreteness: whether something is a tangible object (Paivio, Yuille, & Madigan, 1968);
Imageability: how readily one can produce a mental image for that word (Maguire et al., 2006).
These four elements characterize a word’s perceptual accessibility. Because verbs tend to lie on the less perceptually accessible end of this continuum, they are generally more difficult to learn. Nouns also fall at various points along a perceptual continuum. A mental image can easily be created for elephant but not for justice. Words with more perceptual accessibility are easier to learn. The idea that words fall along a continuum from less to more perceptually accessible has important consequences for theories of vocabulary depth. The types of semantic information available for words along the continuum will be qualitatively different, so a learner’s semantic network for a concrete noun will look different from his or her semantic network for an abstract verb. This also suggests that the instructional information that can be provided for different word types will also be different.
Semantic Networks for Concrete Nouns
Functional information
For concrete nouns, functional information, or information about what an object does or is used for, has been found to be highly salient for preschool word learners (Booth, 2009; Greif, Nelson, Keil, & Gutierrez, 2006).
Hierarchical information
This dimension involves the ability to add nodes to the semantic network and to categorize the relationships among nodes, such as the ability to identify superordinates and subordinates (Verhallen & Schoonen, 1993). Another type of hierarchical relationship among concrete nouns is that of part–whole relations (Henriksen, 1999; Verhallen & Schoonen, 1993). For a word such as fish, various characteristic component parts may be included in a child’s semantic network, such as scales, fins, gills, and tail.
Perceptual qualities
For concrete nouns, the object’s perceptual qualities constitute additional nodes in the semantic network. Perceptual information about objects (e.g., cats have fur, armor is made out of metal, gold is yellow) provides important fodder for the process of categorizing what type of object or material something is, and how it can be differentiated from other similar objects or materials.
Semantic Networks for Concrete and Abstract Nouns, Verbs, and Adjectives
Synonyms
Another key aspect of a semantic network for concrete and abstract nouns, verbs, and adjectives is synonyms, or the core meaning(s) of a word. A synonym can be either a single word or a short, decontextualized definition when a single-word synonym does not exist (Miller & Fellbaum, 1991). Knowledge of synonyms is often the deciding factor in whether a child knows a word, demonstrating a decontextualized knowledge of word meaning. In teaching vocabulary, giving synonyms or short, decontextualized word meaning explanations has been shown to help primary-grade students learn new words (Biemiller & Boote, 2006).
Gestures
There is a growing awareness that embodied experiences of words may help support comprehension and that gestures serve as another way of representing the meanings of words (Glenberg, Gutierrez, Levin, Japuntich, & Kaschak, 2004). Pairing language with gesture, rather than using language alone, was shown to improve comprehension for preschoolers (McNeil, Alibali, & Evans, 2000) and for first and second graders (Glenberg et al., 2004). McNeil and colleagues posited that gestures can act as a scaffold for verbal information, helping to guide children’s attention to the semantic content of complex language. Gesture may also function as an alternative way for children to express knowledge before they can explain it verbally (Capone, 2007). Gestures may be a particularly powerful way of teaching the meanings of verbs. Although concrete nouns have stable perceptual features, verbs are dynamic and require children to abstract the verbal essence of an action (Golinkoff et al., 2002).
Contextual information
Rich word knowledge must include not only semantic information but also an ability to use a word in different contexts (Nagy & Townsend, 2012). Knowing a word means being able to do things with it, and the ability to use a word correctly in context shows a deep, applied knowledge of a word and its use. The ability to appropriately use a word develops over time, progressing from a basic association with the word and its typical context of use (e.g., knowing that the word has something to do with ___ to being able to use the word in a single context, to eventually learning to use the word flexibly in a range of contexts; Clark, 2010).
The Study
This was a vocabulary intervention study designed to increase children’s depth of word knowledge and to address these three questions:
Did children’s depth of vocabulary knowledge for target words increase, as compared with their knowledge of exposure and control words?
Did increases in depth of knowledge for target words vary by word type?
How did the kind of semantic information learned vary by word type?
Participants and Materials
The study involved 240 preschoolers from low-income backgrounds. The children listened to four stories read aloud. Ten target words per book—abstract and concrete nouns, verbs, and adjectives—were selected to be taught. To ensure that the target words were sufficiently difficult, words that more than 30% of students from the previous iteration of the experiment identified correctly at pretest were replaced. The researchers used the same methods to select 17 exposure words and 16 control words that were comparable in difficulty to the taught words and contained similar proportions of the four word types (concrete and abstract nouns, verbs, and adjectives). Exposure words occurred in the stories but were not commented on. Control words were not in the stories.
Procedures
Intervention specialists read two books aloud to students four times over the course of the intervention. Each target word was explained as part of every book reading, once during each reading as the words occurred in the text and once after each reading was completed as part of a vocabulary and plot review. The explanation consisted of the following:
Drawing students’ attention to a word by pointing to the picture, which also helps illustrate meaning (e.g., “Look, the king is wearing spectacles” while pointing to the glasses in the picture)
Definitional information delivered in concise, child-friendly language (e.g., “Spectacles are glasses”), including perceptual, functional (e.g., “The spectacles help the king see better”), and hierarchical information whenever possible
The use of gesture, whenever possible, to kinesthetically reinforce meaning (e.g., “Can you pretend you are wearing spectacles like this?” while the teacher makes spectacles with rounded fingers)
An example of a word in a context other than the one used in the story (e.g., “Look, your teacher wears spectacles, too!”). During the third and fourth readings, students’ verbal participation was encouraged to reinforce each word’s phonological and meaning representations (e.g., “What was the king wearing to help him see?”).
Scoring of Vocabulary Task
Students were asked to define concrete and abstract nouns, verbs, and adjectives verbally or by using gestures. For each word, students were asked, “What is (a) ___?” and a follow-up question, “Can you show me or tell me anything else about ___?” If a student did not respond to a question, the tester moved on to the next word. All student responses were transcribed by testers and also video- or audiotaped. The researchers used seven information unit categories to score student responses for semantic content and contextual information: perceptual qualities, functional information, part/whole, synonyms, gestures, meaningful context, and basic context. The first three categories were used for concrete nouns only. Perceptual qualities included properties such as how something looks, smells, tastes, feels, or sounds. Functional information included any process, purpose, or use for concrete nouns and answers the question, “What do you do with it?” Part/whole described a distinct part of a target word or the whole that the target word was a part of. The remaining categories were used for all word types. Synonyms included any word or short phrase that was equivalent to the word being explained, and provided decontextualized meaning information. Gestures included gestures, actions, or facial expressions (e.g., the teacher uses a scary face to illustrate the word “fierce”) that showed knowledge of the word’s meaning. The researchers also coded for two types of use in context. Meaningful context included responses that showed knowledge of the target word in a typical, meaningful context, along with semantic information. For example, if a student said, “A shovel is used to dig up weeds in a garden,” “used to dig” would be scored for function, and “weeds in a garden” would be scored for meaningful context, because the student used a typical example to explain how a shovel could be used, along with semantic information. Basic context was a simple association between a target word and a typical context, without any use of semantic information. For example, students frequently said, “Santa Claus,” for chimney, a response that does not include any semantic information but still contains an association with a typical context in which the target word is used.
Results
Overall growth in vocabulary depth
Children showed significantly greater growth in their depth of knowledge of taught words than exposure and control words.
Growth in vocabulary depth by word type
Children showed significantly greater growth in their depth of knowledge of concrete nouns as compared with verbs, abstract nouns, and adjectives.
Children learned significantly more verbs than abstract nouns and adjectives.
They showed the least learning for abstract nouns and adjectives; there was no difference between learning of abstract nouns and adjectives.
Students showed significant growth in their knowledge of all semantic information categories for concrete nouns, learning functional information best, followed by meaningful context, synonyms, part–whole relations, gestures, perceptual qualities, and basic context.
Growth in vocabulary depth by word type and semantic information category
Students showed growth in all semantic information categories for verbs, learning synonyms best, followed by meaningful context, gestures, and basic context.
For abstract nouns, students showed significant growth only in their knowledge of synonyms and meaningful context. They showed no growth in knowledge of the basic context and gesture categories for abstract nouns.
Students showed growth in knowledge of synonyms for adjectives. Although meaningful context was taught for all of the adjectives, and gesture was taught for 67% of them, students did not show significant growth in those categories.
Implications
The design and results of this study inform vocabulary instruction by guiding the type of information that teachers and speech-language pathologists (SLP) use to explain new words to preschoolers.
The most perceptually accessible category of words, concrete nouns, was taught with a synonym, an explanation of what the word meant in context, and a reference to a picture in the book. All but one of the concrete nouns were also explained using functional information (e.g., “We use nostrils to breathe”), about half were explained using perceptual qualities (e.g., “Nostrils look like little holes”), and a third of the words were explained by pointing out a part of the object or the whole of which the object is a part (e.g., “Scales are on a fish’s body”). To support word learning for concrete nouns, then, SLPs should not only exploit their perceptual accessibility by using pictures and pointing out important parts of the object but should also explain an object’s function.
The less perceptually accessible words in the study—abstract nouns, verbs, and adjectives—were also taught with a synonym and an explanation of what the word meant in context. Pictures from the book were referenced for two thirds of the abstract nouns and verbs and about a third of the adjectives. Gesture was another important element of instruction for these words: Two thirds of the verbs and adjectives were labeled with a gesture illustrating the word’s meaning.
These results demonstrate that not only were the concrete nouns better learned because of their perceptual accessibility, but they also naturally lent themselves to fuller, more varied kinds of instructional information. The less perceptually accessible words, in contrast, were not only less imageable, less concrete, more difficult to individuate, and without a consistent shape but were also more difficult to define in terms of function or discuss as a part or whole. The data suggest that speed of learning of words may reflect the converging effects of both their perceptual accessibility and the type of information that can be provided.
Teaching context for words was also important for all word types except adjectives, suggesting that children not only need clear semantic information about words but also remember and use information about the typical contexts in which words are used. This may be especially important for words that are difficult to learn. Hearing a difficult, highly abstract word (e.g., “plan” in this study) used in context multiple times allows children to progressively refine their knowledge of the nuances of its meaning.