Purpose: Of the three currently recognized variants of primary progressive aphasia, behavioral differentiation between the nonfluent/agrammatic (nfvPPA) and logopenic (lvPPA) variants is particularly difficult. The challenge includes uncertainty regarding diagnosis of apraxia of speech, which is subsumed within criteria for variant classification.…

These authors cite their own study of the relationship between traditional measures of intelligence and Piagetian measures of cognitive development in support of Glass and Stephens' contention that there are important qualitative differences. They question Humphreys' and Parsons' conclusions on both substantive and factor theoretical grounds. (CTM)

Piaget's model of children's conceptual learning and development was compared with Klausmeier's Conceptual Learning and Development (CLD) model in a longitudinal study. The CLD model suggests four successive levels of concept learning: (1) concrete--recognizing an object which has been encountered previously; (2) identity--recognizing a known…

Background: The population of children with specific language impairments (SLI) is heterogeneous. The present study was conducted to examine this heterogeneity more closely, by identifying and describing subgroups within the population of children with SLI in the Netherlands. Method: A broad battery of language tests and language-related cognitive…