Semantics refers to the knowledge and comprehension of words. Semantic skills may be measured by various receptive vocabulary tests. However, semantics is a broader concept than merely words in the sentence. Compare the sentences below:

  1. I went home and died after the party.
  2. Her father died last week.

Obviously, the meaning of the word died changed to reflect the context. As this example illustrates, it is often difficult to entirely separate semantics from the next level of language—syntax. Syntax refers to the formal relationships between words in phrases or sentences. Examples of such relationships are the subject/verb relationship and the relationship between the verb and the direct object.

Wiig was one of the early researchers to study syntax and semantics (Wiig, Lapointe, & Semel, 1977). This research consistently demonstrated deficits in various semantic and syntactic abilities among children with learning disabilities. For example, these children demonstrate deficits in the ability to apply morphological rules (formation of plurals, verb tenses, and possessives are some examples). Also, comprehension and expression of syntactic structures have been identified as a deficit area among these children. These syntactic structures include relationships between words in sentences and phrases. Understanding who a pronoun applies to and what function is served by a direct object and an indirect object are examples of this syntactic skill. These deficits are apparent both in the child's understanding of the language of others and in his or her own production of spoken language. Finally, at least one of these studies demonstrated that oral language production did not automatically improve with age for students with learning disabilities as it does for other students (Wiig et al., 1977). This may suggest a critical period in which language intervention must take place if such intervention is to be effective.

Recent research has demonstrated that receptive language of particular types of information may be a problem for students with learning disabilities. Abrahamsen and Sprouse (1995) investigated the ability of students with learning disabilities to understand fables that were read to them and to select the correct moral for the fable. Based on the early research, which suggests that average students begin to understand figurative language (i.e., metaphors, similes, idioms, and proverbs) in about the fourth or fifth grade, these researchers presented fables to two groups of students, 14 average learners and 14 students with learning disabilities. The students with learning disabilities were less capable of selecting the correct moral for the fable when four selections were presented, and they were also less capable of explaining their choices. Thus, ambiguity and subtle meanings seem to elude children with learning disabilities.

Perhaps a classroom example is in order. Many teachers issue multiple directions to students in the inclusive class, particularly when it is time to change subjects. However, the students in the class who are learning disabled may have some difficulty in understanding the teacher's meaning. Imagine a teacher who says something like the following: "OK, that's it for spelling today, so you can put your books away. Get out your history homework to pass up. Get your history books and notebooks and put them on your desk."

Note that four separate commands are included in this brief set of instructions. The child must do something with spelling books, history homework, history books, and history notebooks. The child with learning disabilities may very well end up with the history homework sitting on the desk along with the history book and history notebook, when the teacher wanted the homework passed up to the front of the row. This child may also be inclined to misread the referent for the pronoun them in the last sentence, thinking that that pronoun also applied to the history homework. Misreading instructions such as this is a frequently mentioned problem whenever teachers discuss students with learning disabilities, and this problem is related to the inefficient use of language.

Most of the studies in this line of research were group comparisons that identified a group that had disabilities and a group that did not and then compared them on the variable of interest. Although such studies are useful in the early phase of development in a particular research area, they should lead to several other types of research. It is the responsibility of the researchers in any given area to show why a particular research area is important by demonstrating relationships between variables in the area and academic variables. Some indicators of semantics and syntax are related to school achievement, but research in these areas of language has failed to establish a case that these linguistic deficits represent a major cause of failure in school for children with learning disabilities (Feagans, 1983). Also, those variables that do relate to achievement tend to be variables that represent complex symbolic operations (understanding sentences, phrases, and morphological rules) as opposed to merely decoding words and speaking correctly. As a result, research emphasis shifted to studies of language beyond the study of isolated words and sentences in the 1980s and 1990s.