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ASSESSMENT OF RECEPTIVE LANGUAGE
Janet A. Lees
When faced with the need to assess a childās language development in order to produce a profile of strengths and weaknesses that can be used to plan intervention, most therapists begin by investigating receptive-language abilities. Receptive language is the human ability to understand and process symbols, particularly verbal ones, as part of the communicative act (Cooper, Moodley and Reynell, 1979). Thus, it includes the development of pre-linguistic receptive abilities; for example, the understanding of prosodic features or symbolic noises such as animal sounds, as well as the comprehension of complex grammar or lexical items. From this definition it is clear that the clinical task of receptive-language assessment is quite a broad one. However, in practice it is informed by several basic questions as well as our understanding of the development and cerebral organization of receptive language. The basic questions that a clinician needs to consider during the assessment process are:
1. What is the present status of the childās receptive language?
2. If it is mismatched with the rest of the childās development and/or the childās age, is intervention required and if so what?
3. What is the prognosis for further development?
These questions will form the basis of the discussion of the assessment of receptive language in this chapter. The clinical population will be considered in three main age bands; preschool (under 5 years), school-aged (5-10 years) and teenage children (11-16 years). In addition there will also be some consideration of the needs of children with unusual receptive problems including the Landau-Kleffner syndrome (Landau and Kleffner, 1957).
WHAT IS THE PRESENT STATUS OF THE CHILDāS RECEPTIVE LANGUAGE?
The clinicianās judgement of a childās receptive-language abilities is informed in two ways: a knowledge of the usual process of language development and a model of the way in which children process language. These two ideas are fundamental to all assessment procedures, both formal and informal. In order to make appropriate decisions during the assessment process a clinician needs to consider new developments in those two fields. The majority of assessment procedures for children are based on developmental levels or stages, and a minority take a view of language-processing. For the valid assessment of a particular child these two notions need to be kept in balance. The choice of particular assessment techniques will depend on a knowledge of the way in which these two ideas are related in any one assessment procedure.
LANGUAGE DEVELOPMENT
It is recognized that language development, along with other aspects of development, has both individual variability as well as general population trends. It is not the intention of this chapter to provide an overview of modern studies in language development. Rather, the clinicianās attention is drawn to three particular aspects of the study of language development that are important to receptive abilities: the prelinguistic stage, the age-related or skills-related models of development and the concept of critical period in our understanding of language development.
The importance of the prelinguistic stage for the later development of language has been increasingly recognized in research studies (see Martlew, 1987 for a review). Subsequently, some new assessment procedures have also focused on this area (Gerard, 1986; Dewart and Summers, 1988). Where the child has a severe communication problem it will be particularly important to establish the presence of even the most basic prelinguistic skills. The importance of development of this stage should not be overlooked in retrospect, as in the taking of a case history in an older child. Evidence of very early impairment in communication skills will be significant for predicting prognosis. On-going evidence of impairment in basic skills like turn-taking or the use of gesture will affect the choice of management strategies.
It is usual to refer to a model of so-called ānormalā development when assessing a childās progress. By this means, childrenās performance is related to the expected average progress of their peers. Two different, but related, approaches are used: the age-related or skills-related models: In an age-related approach the childās development is compared to the expected age level at which a certain skill is generally achieved. The approach is straightforward and is the basis of most developmental screening (Sheridan, 1973). It can be used in check-lists which indicate whether or not a child has been observed to demonstrate a particular skill (Bzoch and League, 1970).
In the skills-related approach, the age at which the child achieves the skill is not as important as the sequence in which the skills are achieved, and the way in which skills in one area relate to other areas of development. Thus, certain preliminary symbolic skills are required before the child can be expected to move on to the first level of verbal comprehension. In the ānormalā model the development of the content, form and use of language (Bloom and Lahey, 1978) are seen to be related to each other. When one aspect of development falls behind others, then a mismatch in development results. This mismatch is generally referred to as a delay in development but this simple idea can be misleading. All aspects of development may be delayed such that the child appears to be functioning as a younger child. This may be the long-term effect of prematurity or a manifestation of general learning difficulties. Where only one aspect of development appears to be delayed in relation to others, this may be described as specific delay, as in specific developmental language delay. This name suggests that all other aspects of development are normal and that language development is just slower. Further, it suggests a belief that the child can catch up this delay. In a longitudinal study to look at the relationships between the development of motor and language skills, and to test the hypothesis of maturational lag, Bishop and Edmundson (1987) found that for the majority of children in their sample the evolution of their development could be accounted for in terms of maturational lag. However, for a small group of children the presence of persisting deficits were difficult to account for using this model. It is the small group of children who present with mismatched development in respect of language to other skills, who are usually referred to as disordered or deviant.
For those children with a persistent mismatch between language and other skills the use of the term deviant or disordered development removes an emphasis on the idea that they will catch up eventually. It has been postulated that there are critical periods in language development; times by which certain stages need to have been reached if full potential is to be realized. Mogford and Bishop (1989) summarized the evidence of studies of language development in relation to the notion of critical period. They concluded that current data are inadequate to answer all the questions about the possibility of prolonged learning in children who have persistent language deficits.
MODELS OF LANGUAGE PROCESSING
It is clear that a range of factors influences the language development of a particular child. This is related to the input of language, the way in which it is processed in the brain and its output. In order to develop language it seems likely that children have to hear and experience its complexities, have an adequate language-processing mechanism and the necessary equipment to be able to produce their own language usually, but not exclusively, in the form of speech. The major organ of language input is the ear. What we hear is conveyed to the brain by the auditory mechanisms of the middle and inner ear and along the auditory nerve (VIII cranial). The efficiency of this mechanism may be impaired by congenital damage (Rubella syndrome, hereditary congenital hearing loss, etc.). However, the commonest form of interference to the competence of the auditory mechanism in childhood is otitis media; infection of the middle ear. This often results in fluctuating conductive-hearing loss, but its implications for language development are not agreed. Klein and Rapin (1989) reviewed over fifty studies of language performance in children with otitis media and concluded that āthe cause-effect relationship between early recurrent otitis media and later cognitive and language development remains uncertainā (p. 108). They concluded that there may be a transient effect on language skills but that this was unlikely to be of long-term significance in children who were otherwise normal. However, they further stated that in sub-optimal conditions for development, like environmental deprivation or cognitive deficiencies, the additional effects of otitis media may be greater.
What is received by the ear and transmitted through the auditory nerve is processed by the receptive-language components of the brain. However, it is not possible to trace the direct path that each āpieceā of receptive language takes within the brain. It is thought that an area of the temporal lobe of the dominant cerebral hemisphere, usually the left, plays a major part in the reception of language information. Called Wernickeās area, this function has been attributed here predominantly on the basis of the analysis of deviant language behaviour in adults who sustain damage to it. One of the main features of Wernickeās aphasia in adults is a loss of verbal comprehension. Despite it being recognized that similar damage sustained in childhood does not have the same consequences (Bishop, 1989), and that even in adults the pattern may be more variable than originally supposed (Marshall, 1986), there has been little progress in the development of a more child-centred model for our understanding of the cerebral organization of language-processing. Evidence from a longitudinal study of acquired aphasia in childhood (Lees, 1989) confirmed that severe receptive problems occurred in the majority of the children, not all of whom had demonstrable damage to Wernickeās area.
A better model for receptive language in children will need to consider clinical data carefully, as Bishop and Mogford (1989) have demonstrated. The way in which factors like neurological development, genetic components, environment and auditory competence interact in the development of receptive language in childhood has only recently started to be addressed. The importance of this approach for the clinician is that rather than take the exclusive view in the diagnosis of language impairment, in which the problem is seen to be the effect of one unknown cause, a more inclusive view which promotes a holistic understanding of the child and his or her language needs should inform practice.
Box 1.1
Factors affecting language input
Environmental factors:
environmental deprivation
hearing impairment (otitis media)
twin or other family factors
bilingual background
family are not users of verbal language
Genetic factors:
inherited hearing loss
congenital learrning disorder, general or specific
Neurological factors:
disorder of cerebral development
acquired lesion/s
If we take the view that language is a complex process of many stages which begins with the received signal and ends when the appropriate response has been correctly received by another, we can see that there are many points where the system may break down or become vulnerable to interference. An impairment in an early stage of the process may affect the development of a later stage while a problem at a later stage can affect an earlier part of the process. Bishop (1987) calls these interferences ābottom upā and ātop downā influences respectively. She considers their importance for the assessment of the childās receptive language. It is clear that a problem of the auditory perception of speech sounds may lead to the confusion of two sentences like:
he rode the bicycle
and
she rode the bicycle
where the two are distinguishable only to someone who correctly differentiates the initial minimal pair. A failure to comprehend these two sentences correctly could not immediately be attributed to a grammatical deficit. Equally, a high-level problem in auditory perception, of the kind where background noise interferes with the efficiency of auditory-verbal processing, could be interpreted as a failure in grammatical comprehension unless this factor is also consi...
