Qualitative Deficits Research Articles

Adequate Control Procedures in Experimental Studies of Developmental Disabilities

The problems of establishing both quantitative and qualitative deficits in the behavioural profiles of various diagnostic subcategories of developmentally-disabled children are discussed in a developmental context. Examples of clinical experimental studies from the literature concerned with the syndrome of early-onset psychosis are used to illustrate the importance of methodologically controlling for maturational variables. Methods of appropriate matching of control groups are suggested which should facilitate the delineation of specific and general deficits in subgroups of developmentally-delayed children.

Effects of caudate nuclei or frontal cortical ablations in kittens: Maze learning

Cats which had received bilateral lesions of the caudate nuclei and the frontal cortices during the first month of life were tested as juveniles on T-maze position habit and spatial reversal tasks. Intact and sham-operated littermates served as controls. All animals of all groups were capable of learning the spatial discrimination and to successfully reverse that habit. While maintaining many of the perseverative characteristics of adult-operated acaudates, the kitten-operated acaudates showed the fewest number of trials to acquire the position habit and to complete 30 reversals. There was a direct relationship between the size of the lesion and the number of perseverative errors made by the acaudate animals. The afrontal cats showed more reversal errors and were unmotivated and distractable. The data suggest for the tasks used here that although there may be similar qualitative deficits the overall effects on performance are not as great when the lesion is inflicted in the neonate compared to the adult. The data imply that many factors contribute to this recovery, e.g., early experience.