Developmental aphasia

Abstract

If our observations are correct and our speculations tenable, we may regard the aphasic child as one who may be defective in:
(a) storage and retrieval of sounds;
(b) in phonemic generalization;
(c) in sequencing; and
(d) more generally, and more broadly psychologically, in ability to generalize and to apply principles to situations that share a critical and determining common feature.
The aphasic child may be born structurally ill-equipped for the acquisition of verbal behaviour. It would be helpful if at this point, we could indicate with confidence the requisite capacities and the functional structures which enable all but a small percentage of children to begin to speak and to develop verbal behaviour according to the expectations of the concerned members of their environment.
We may speculate but we are by no means certain as to how a child can understand verbal formulations he has never heard before, and to produce his own formulations with considerable confidence that what he says will be understood by others. We assume, of course, that normal hearing acuity, normal perceptual ability, normal sequencing, and a fair amount of intellect are required for the acquisition of language. In regard to intellect, it is important to appreciate that most children who are mentally subnormal, unless the subnormality is profound, nevertheless learn to speak. Yet some children who indicate through non-verbal behaviour that they have adequate intelligence, that is, they perform about as expected in situations where verbal mediation is not required — fail to acquire language without direct therapeutic intervention. The aphasic and some autistic children are among those with adequate intelligence who do not learn to acquire language spontaneously. Some clinicians and not a few linguists take recourse to a philosophic attitude about what the capacities and structures might be for a child to acquire speech. The position they take is that a child learns to speak because speech is a human species-specific function. So, according to Lenneberg,¹¹
"The development of language, also a species-specific phenomenon, is related physiologically, structurally, and developmentally to the other two typically human characteristics, cerebral dominance and maturational history. Language is not an arbitrarily adopted behaviour, facilitated by accidentally fortunate anatomical arrangements in the oral cavity and larynx, but an activity that develops harmoniously by necessary integration of neuronal and skeletal structures and by reciprocal adaptation of various physiological processes." 
We do not pretend that all or even most of the evidence needed to explain the lack or severe delay of speech in aphasic children is presently available. What evidence we do have strongly suggests to us that aphasic children are lacking in the basic capacities and in the correlative abilities and integrations necessary for normal language acquisition. Perhaps these children are not pre-wired neurologically as well as they should be to integrate what they need, to be proficient receivers and senders of sound signals. Perhaps aphasic children have a slower central nervous system maturation than normal children or even our mentally subnormal children who acquire speech. It is likely that some aphasic children develop perceptual defences because of demands made on their systems which are beyond their capacities at critical times. These are some, but not all of the possibilities which must be considered if we are to understand the nature of the problem of developmental aphasia, and if we are to develop rational and significant therapeutic and training procedures.