4.4 Linguistic Sources of Comprehension Difficulti...
This section outlines several linguistic sources of text complexity that have been documented to present comprehension challenges to students in disciplinary learning. They are specialized vocabulary, grammatical metaphor, expanded noun phrase, intricate sentence, and pronoun. These linguistic features, common among academic and disciplinary texts, are well motivated: they configure in functionally different ways across different genres, disciplines, and contexts. Texts with greater concentrations of these features are generally less familiar to students and hence present a greater challenge for reading comprehension, above and beyond unfamiliar topics. An awareness of the lexicogrammatical patterns that can cause comprehension difficulties gives the teacher a principled basis for designing reading instruction that helps students work through challenging texts.
Three disciplinary texts — one each in science, history, and mathematics— are used to exemplify the five linguistic features identified above. Text 4-2 is an excerpt on environmental science from A Window on Eternity, written by an American biologist, that examines the near destruction and rebirth of Gorongosa, one of the biologically richest places in Africa. Text 4-3 is taken from The World Must Know, a historical account that examines the atrocities of the Holocaust as told in the United States Holocaust Memorial Museum. Text 4-4 is an excerpt from an American high school geometry textbook.
Text 4-2
The loss of a single tree species often results in the elimination of multiple moth, beetle, and other insect species dependent on it. Similarly, the disappearance of a key pollinator can threaten multiple plant species. When honeybees recently suffered a die-off, probably from a combination of pesticides and inbreeding, some crops dependent on their services declined with them. When such symbioses are tight and highly specific, as between some tropical orchids and euglossine bees, the extinction of one partner means doom for the other. (Wilson, 2014, p. 125)
Text 4-3
The location and operation of the camps were based on calculations of accessibility and cost-effectiveness — the hallmarks of modern business and administrative practice. The killing was done coolly and systematically under the supervision of bureaucrats. German corporations profited handsomely from the industry of death. Pharmaceutical firms tested drugs on camp inmates without any regard for toxic side effects. Companies bid for contracts to build ovens and supply the gas used for extermination. German engineers working for Topf and Sons supplied one camp alone with forty-six ovens capable of burning 500 bodies an hour. (Berenbaum, 2006, p. 103)
Text 4-4
The sum of the measures of the interior angles of a polygon equals the product of 1800 and two less than the number of sides. The measure of each angle of a regular polygon equals the sum of the angle measures divided by the number of angles. (Charles et al., 2004, p. 463)
4.4.1 Specialized Vocabulary
Two types of specialized vocabulary can present comprehension challenges when reading texts in academic disciplines. One type is technical vocabulary, which includes words, phrases, and acronyms that experts use to capture key disciplinary concepts. These technical terms — such as species, pollinator, symbioses, and euglossine bees in Text 4-2 — are essential to the creation and organization of specialized knowledge in specific disciplines. Without them, disciplines as we know them today would not have existed. Because of its low frequency of occurrence outside of academic/disciplinary contexts, technical vocabulary tends to be less familiar to students and can thus create reading problems. Another type of specialized vocabulary is commonplace words and phrases that take on special meaning in particular contexts or disciplines. These words — such as product and sides in Text 4-4 — are usually easy to decode and familiar to students because of their high utility in everyday contexts, but they can pose comprehension difficulties when used in a different, non-vernacular sense. Comprehension problems can exacerbate when a heavy load of specialized vocabulary is present in a short chunk of text.
4.4.2 Grammatical Metaphor
Grammatical metaphor is a key feature of academic and disciplinary texts. As noted in Chapter 2, it refers to linguistic choices that realize meaning in ways that are incongruent with how humans typically construe their everyday experience. In congruent realizations, things are presented in nouns, processes in verbs, qualities in adjectives, circumstances (i.e., when, where, how, in what manner, to what extent) in adverbs or prepositional phrases, and logical-semantic relations in conjunctions. In incongruent realizations, processes, qualities, and circumstances are presented in nouns, and logical-semantic relations in nouns, verbs, or prepositions.
One prominent type of grammatical metaphor is nominalization, which involves the use of nominal group (i.e., noun and noun phrase) as a substitute for another grammatical class or structure such as verb, adjective, adverb, prepositional phrase, conjunction, or clause. For example, this 23-word sentence from Text 4-3, The location and operation of the camps were based on calculations of accessibility and cost-effectiveness — the hallmarks of modern business and administrative practice, contains seven nominalizations (all underlined). It can be expressed in the more congruent language of everyday life as "The Nazis determined where the camps were to be located and how they were to be operated by calculating how accessible and cost-effective they are. This is characteristic of how modern business and administration operate." The grammatical shifts from verb, adjective, and clause to nominal group that accompany the transference from congruent to incongruent ways of realizing meaning are shown in Table 4-1. Note that these shifts also involve the disappearance of historical actors (the Nazis) who were perpetrators of the activities.
Table 4-1 Congruent and Incongruent Linguistic Realizations of Meaning(https://www.daowen.com)
All three texts are populated with nominalizations, as can be seen in Table 4-2. Some of these terms, such as inbreeding and symbioses in Text 4-2 and product in Text 4-4, have also become technical or semi-technical concepts with specialized meanings. They work in conjunction with technical vocabulary and other nominalizations to create an abstract textual world that is alienating to students and presents comprehension challenges to them.
Table 4-2 Nominalizations in Three Sample Texts
As these examples reveal, nominalization has consequences for the organization of the clause and even of subsequent sentences. By synthesizing or condensing prior discourse into a nominal group that then functions as participant in a new clause, nominalization helps create a cohesive text that flows. For example, such symbioses in Text 4-2 reintroduces the idea presented in the previous three sentences (i.e., interdependency of species) as a nominal group that then becomes the subject of the first clause of the last sentence. Similarly, the killing (second sentence) in Text 4-3 distills the message from the first sentence (massacre in concentration camps) into a nominal group that then serves as the topic of discussion in the sentence. From this perspective, nominalization is an important grammatical resource for organizing information and developing argument in a text.
At the same time, however, nominalization creates a discourse that is simultaneously dense, technical, abstract, and nebulous, making the text much more difficult to comprehend and critique. By compressing and distilling what is normally expressed in a clause into a nominal group that becomes merely a grammatical participant in the clause, nominalization increases the informational load (i.e., density) of the clause. It also creates abstraction and technicality by suppressing agency and eliminating concrete referential information. In other words, by ways of nominalization, discursive vitality (with actors actually engaging in action) is transformed into a stasis or an abstraction. This has the effect of naturalizing something that is fuzzy and opaque, making it sound technical, precise, stable, and authoritative. It also masks power relationships by downplaying individual responsibility for an action or completely removing people or other agents from the interaction.
For example, in the first sentence of Text 4-2, the agents responsible for the loss of tree and insect species are hidden and have to be inferred from the surrounding text. In the first sentence of Text 4-3, the party responsible for selecting and operating the site for concentration camps (i.e., the Nazis) is buried and has to be recovered for reading comprehension. Similarly, in Text 4-4 the actor responsible for measuring the interior angles of a polygon and adding up these measures is buried so that the focus of the information is on the mathematical concepts of measurement, addition, multiplication, subtraction, and division, rather than on the concrete mathematical processes of measuring, adding, subtracting, multiplying, and dividing. Because nominalization tends to obscure many of the semantic relations that are otherwise transparent in the clause structure, it reduces the reader's sense of what is truly involved in an interaction. As such, nominalization is an instrument of manipulation prized by experts in many disciplines. Students who do not understand how nominalization works are less likely to recognize the hidden meanings and develop as critical readers.
This trade-off between a gain in textual information (facilitating discursive flow) and a loss of ideational information (suppressing agency) favors the specialist (who can tolerate a high level of implicitness because of their content knowledge) and disadvantages the novice (who are still in the process of developing language and literacy at the same time they are building content knowledge). Nominalization backgrounds information that disciplinary experts are able to retrieve (from either preceding text or prior knowledge) for understanding but novice or uninformed readers often have difficulty recovering for comprehension. Because reading comprehension always demands activation of prior knowledge, the lost information makes it especially challenging for those without appropriate content knowledge to properly identify the processes and participants involved in a given situation and how they are related to each other.
Another type of grammatical metaphor that presents a challenge for reading is logical metaphor, which realizes logical-semantic relations between two clauses in incongruent ways. In congruent realizations, logical links between two clauses are realized in conjunctions; but in incongruent realizations, these links are realized clause internally in linguistic resources such as nouns, verbs, adverbs, or prepositions. This way of using language makes the logical connections in the text more difficult to discern for students, especially those lacking appropriate content knowledge and/or language proficiency. For example, Text 4-2 is an environmental science text that offers causal/consequential explanations about the extinction of plant and animal species in Gorongosa National Park. The logical connections in the text are realized in verbs and prepositions. In the first sentence, the verb phrase results in offers a consequential explanation, i.e., the loss of a single tree species causes the elimination of multiple moth, beetle, and other insect species. The second sentence is what Fitzgerald (2014) called an "asyndetic construction", which realizes causality not through an explicit marker (e.g., conjunction) but through the modal verb can. It means that the disappearance of a key pollinator is likely to have the effect of causing multiple plant species to become extinct. In the third sentence, the prepositions from and with construct causal explanations, suggesting that (a) honeybees suffered a die-off probably because of the human use of pesticides and inbreeding among honeybees, and (b) some crops declined because honeybees died. The last sentence constructs a consequential relation through a verb that denotes the relational process (means), suggesting that the extinction of one partner species causes the other species to die too. When causal explanations are constructed with linguistic resources other than the usually familiar resource of conjunctions such as because and so, the true causes of and eventual solutions to environmental problems are obscured. This, coupled with the burial of agency through nominalization, can impede students' full comprehension of environmental texts and inhibit their active involvement in solving environmental problems (c.f., Chenhansa & Schleppegrell, 1998).
Similarly, in Text 4-3, the verb phrase were based on in the first sentence implies causation: accessibility and cost-effectiveness determined where concentration camps were to be located and how they were to be operated. The use of from in the third sentence suggests that because killing Jews became an industry, German corporations were able to make good profits. Fitzgerald (2014) suggested that the reason that authors make causal relationships implicit could be varied interpretations, political sensibilities, lack of evidence, or a combination of these. From a discursive point of view, by construing causal relations within clauses (through verbs, nouns, or prepositions) rather than between clauses (through conjunctions), authors have a much wider array of linguistic resources to present cause-effect relations (Martin, 2002). At the same time, such within-clause logical reasoning necessitates the causes and effects to be constructed as abstract "things", often in the form of nominalizations. In short, grammatical metaphor makes explanations less accessible to comprehend and critique for students. In effect, it "sets apart those who understand it and shields them from those who do not" (Halliday & Martin, 1993, p. 21).
4.4.3 Expanded Noun Phrase
Texts in academic disciplines tend to be lexically dense, meaning that they pack a large quantity of content words into individual clauses. Expanded noun phrases are a key contributor to lexical density, as they enable the author to pack a heavy load of information into the clause (Fang, Schleppegrell & Cox, 2006). According to Halliday and Martin (1993), lexical density is typically 2-3 for spontaneous speech and 4-6 for general written texts, but can be 10 or higher for specialized texts in academic disciplines. The following sentences from Texts 4-2, 4-3, and 4-4, for example, have a lexical density score of at least 10, and it is the expanded noun phrases (italicized) that render them informationally loaded.
· The loss of a single tree species often results in the elimination of multiple moth, beetle, and other insect species dependent on it.
· The location and operation of the camps were based on calculations of accessibility and cost-effectiveness — the hallmarks of modern business and administrative practice.
· The sum of the measures of the interior angles of a polygon equals the product of 1800 and two less than the number of sides.
· The measure of each angle of a regular polygon equals the sum of the angle measures divided by the number of angles.
Lexically-dense texts present greater processing demands than lexically-sparse texts because, according to cognitive psychologist George Miller (1969), human working memory can hold approximately seven items (content words, numbers, facts) at one time before they fade into oblivion. When multiple expanded noun phrases are present in a single clause, the clause can be especially dense and difficult to process. Complications for comprehension can occur when one nominalization is embedded within another to create an expanded noun phrase that is simultaneously dense and abstract, as the above examples illustrate.
4.4.4 Intricate Sentence
Texts that are grammatically intricate contain long sentences, each stringing together multiple clauses through coordination and/or subordination. Grammatical intricacy is a feature of spontaneous speech. It does not typically present problems for listening comprehension because in listening, text is processed "largely at the level of meaning" without conscious attention to wording (Halliday, 2005, p. 350). In reading, by contrast, text is processed at the level of wording, with the reader predisposed to "take a synoptic view of what it means" (Halliday, 2005, p. 344). This means that texts with high grammatical intricacy tend to be difficult to follow when read. As Perera (1982) pointed out, while length per se does not necessarily make a sentence easier or more difficult to comprehend, a long sentence that contains several clauses with complex logical-semantic relationships among them is very often hard to read. The following two sentences, the first consisting of five clauses and the second six clauses, are also taken from Wilson's (2014) A Window on Eternity. They each encode a series of logical-semantic relations through subordinate and coordinate clauses that can be difficult to untangle for inexperienced or uninformed readers.
· At the terminal of one of the gorges is one such cave, from which a stream flows, and which may have been occupied by humans and the ancestors of humans since humanity began, making it potentially prime site for further archaeological exploration. (p. 29)
· And now that the rain forest of Mount Gorongosa is also saved, and providing the water distribution of the park is protected, and providing the long-term effects of climate change are not overwhelming, there is no reason to fear that the ecological cycle that worked for thousands of years in the past will not go on for thousands of years into the future. (p. 53)
4.4.5 Pronoun
A pronoun is a word that replaces a noun or an idea in a sentence. It is a powerful device for establishing cohesion in a text and for avoiding cumbersome repetition of the same noun every time it is mentioned. Pronouns such as personal pronouns (e.g., they, it, he, we), demonstratives (e.g., this, that, such, these, those), and relative pronouns (e.g., who, which, that) can create comprehension problems for readers (especially those lacking appropriate background knowledge) if their referents are not transparent. Referential ambiguity can arise when (a) multiple referential possibilities exist for a pronoun, (b) the distance between a pronoun and its referent is so great that it impedes the recognition capability of the reader's working memory, or (c) the precise referent for a pronoun is difficult to pinpoint in the text. The first sentence in Text 4-2, for example, contains a pronoun "it", whose referent (a single tree species) is far away at the beginning of this 23-word sentence. The precise referent for the demonstrative "such" in such symbioses (last sentence) is not easy to identify because it refers not to a particular word or phrase in the text, but to the idea or thesis discussed in the preceding three sentences. Identifying and tracking referents is a critical reading skill that involves both content knowledge and discursive insights.
4.4.6 Summary
The five linguistic features discussed here — specialized vocabulary, grammatical metaphor, expanded noun phrase, intricate sentence, and pronoun — occur with regularity in academic and disciplinary texts; however, they may not always be all present or equally distributed in a single text. These linguistic sources of complexity are not by themselves easy or difficult to understand. The degree to which they present challenges to reading comprehension depends not just on the frequency, concentration, and context of their occurrences but more importantly on reader characteristics (e.g., motivation, language proficiency, cognitive aptitude, background knowledge, literacy experience) and task requirements (e.g., reading for enjoyment vs. reading for detailed summary). This means that reader and task factors should be among the first considerations when evaluating the potential impact of text complexity on reading comprehension (Wixson & Valencia, 2014). Teachers are in the best position to evaluate whether one or more linguistic features present specific comprehension challenges to particular readers in a given task. Understanding the various ways text complexity is constructed, as well as the reasons behind and the effects of these constructions, is the first and critical step towards not only assessing text difficulty but more importantly providing instructional support that enables students to cope with the challenges of complex texts and develop as engaged and critical readers. With an intimate awareness of, as well as explicit knowledge about, text features and their potential impacts on comprehension, teachers will, in the words of Hiebert (2014), "regain a sense of agency and creativity" and be better equipped to "craft a tailored approach to their classroom and their individual learners" (pp. 16-17). This sense of empowerment is key to developing what Duffy (2005) called "visionary" and "entrepreneurial" teachers, who do not have to rely on prepackaged commercial programs but are capable of making independent, informed decisions about curriculum and pedagogy.