The paper presents results of the neuropsychological assessment of processes involved in the maintenance of activation (Luria’s Unit I functions) in 64 firstgraders who demonstrated various levels of academic success. On the basis of this assessment, the children were divided into three groups: (i) the children without any deficit in the Unit I functions (CONTROL children), (ii) those predominantly showing slowness/fatigue (SLOW children), and (iii) those who can be considered as predominantly hyperactive-impulsive (HYPERACTIVE children). It is shown that, relative to controls, both SLOW and HYPERACTIVE children show reduced academic scores and the decrease of most indices that characterize functions of the Units II and III. The weaknesses of executive and visual-spatial functions are predominantly observed in HYPERACTIVE children, whereas SLOW children usually show some deficit in processing of kinesthetic (proprioceptive) and audio-verbal information. Children with functional weakness of the Unit I functions show an overall reduction in performance and its speed in the computerized versions of the “DOTS” and “SCHULTE—GORBOV tables” tests. In HYPERACTIVE children, deficits are observed in the most difficult tasks (those probing mostly into planning and control functions), and their performance is the most unstable. In SLOW children, the performance rate is noticeably decreased for the moderate-to-difficult tasks. Overall, the data reported contribute to the understanding of the diversity of Unit I functions deficits and their relation to the learning difficulties experienced by children in the primary school.

The paper presents results of the neuropsychological assessment of processes involved in the maintenance of activation (Luria’s Unit I functions) in 64 firstgraders who demonstrated various levels of academic success. On the basis of this assessment, the children were divided into three groups: (i) the children without any deficit in the Unit I functions (CONTROL children), (ii) those predominantly showing slowness/fatigue (SLOW children), and (iii) those who can be considered as predominantly hyperactive-impulsive (HYPERACTIVE children). It is shown that, relative to controls, both SLOW and HYPERACTIVE children show reduced academic scores and the decrease of most indices that characterize functions of the Units II and III. The weakness of executive and visuo-spatial functions are predominantly observed in HYPERACTIVE children, whereas SLOW children usually show some deficit in processing of kinesthetic (proprioceptive) and audio-verbal information. Children with functional weakness of the Unit I functions show an overall reduction in performance and its speed in the computerized versions of the “DOTS” and “SCHULTE—GORBOV tables” tests. In HYPERACTIVE children, deficits are observed in the most difficult tasks (those probing mostly into planning and control functions), and their performance is the most unstable. In SLOW children, the performance rate is noticeably decreased for the moderate-to-difficult tasks. Overall, the data reported contribute to the understanding of the diversity of Unit I functions deficits and their relation to the learning difficulties experienced by children in the primary school.