A child with specific language impairment (SLI) does not acquire normal language ability at the appropriate age despite having adequate hearing and normal nonverbal intelligence, and no neurological or sensorimotor handicap. Current diagnostic criteria include deficient expressive and/or receptive language, and a substantial discrepancy between nonverbal performance and language skills (the discrepancy criteria). Common clinical findings are deviant phonological, morphological or syntactic forms used in utterances, omitted words in sentences, and deficient understanding of words or sentences. SLI is regarded as a neurobiologic disorder. The factors most often suggested to underlie SLI are deficient discrimination between rapidly changing stimuli, poor short-term memory (STM), and problems in auditory or verbal processing. However, findings in SLI studies are contradictory, and the core problem of the disorder is still under debate. So far differential diagnostics between SLI and other disorders in the spectrum of developmental disordes, social-emotional disorders and learning difficulty are also undetermined. The major objectives of the present work were 1) to carry out a descriptive analysis of findings of a clinical sample of SLI compared to a sample of normally developing children, 2) to evaluate relationships of these findings with findings and conclusions in the literature concerning especially factors underlying SLI and factors related to cognitive development of children with SLI, 3) to find out if the present data provides evidence that deficits in long-term memory is a factor explaining SLI, and, finally, 4) to evaluate merits of the present clinical practice. The study group is based on clinical material. They are 78 children referred to the Tampere University Hospital on the basis of SLI. Inclusion criteria were nonverbal ability on age level but deficits in either expressive or receptive language, or in both. The control group (101 children whose development had been followed up in a local well-baby clinic) with no known delay in development was gathered from two kindergartens and three well-baby clinics after their parent´s consent. The children´s linguistic, verbal and nonverbal performance and motor skills were evaluated clinically and by the ITPA, Reynell, Bo Ege, Boehm, WPPSI, WPPSI-R, WISC-R (or Leiter) tests, and by the motor test of Stott, Moyes and Henderson. The study group´s general history was gathered by interviewing parents, whereas the control children´s parents completed a questionnaire. The clinical picture of the study group was in agreement with the findings reported in the literature concerning SLI. Discriminative ability and auditory span differed between the LI and control groups, likewise discrepancy between verbal and nonverbal performance. However, in agreement with criticism of the diagnostic criteria for SLI, there were also children in the study group with clear evidence of SLI in their linguistic skills but who did not fulfil the discrepancy criteria, or the criteria based on standard deviations in linguistic tests. On the other hand, in the control group there were children with age-appropriate linguistic ability but a marked discrepancy between verbal and nonverbal performance. Thus, the present study suggests that the diagnostic criteria should be reconsidered. Further, averaging scores in psychometric tests should be avoided. It seems relevant to include age-appropriate visual reasoning in the diagnostic criterion but the possible effects of SLI and underlying factors on psychomotor and social-emotional development should be reconsidered. Considering the results of the present study and the literature, it will be suggested that deficient discrimination and memory functions are the factors underlying SLI. Moreover, considering the theoretical background adopted in this study, it seems that the environmental support given for children with SLI does not widely enough correspond to the underlying factors. Finally, it seems that currently SLI disorder is considered far too much as a disorder of mainly speech and language development. Instead, it should be taken as a sign of underlying neural deficits to be compensated, not only during actual development of speech and language but in later years, too. In conclusion, the present study suggests that current clinical practice in diagnosing SLI should be reconsidered in many respects.
