Institut für Psychologie (bis Sept. 2007)
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No abstract available.
Brain potentials during mental arithmetic: effects of extensive practice and problem difficulty
(1994)
Recent behavioral investigations indicate that the processes underlying mental arithmetic change systematically with practice from deliberate, conscious calculation to automatic, direct retrieval of answers from memory [Bourne, L.E.Jr. and Rickard, T.C., Mental calculation: The development of a cognitive skill, Paper presented at the Interamerican Congress of Psychology, San Jose, Costa Rica, 1991; Psychol. Rev., 95 (1988) 492-527]. Results reviewed by Moscovitch and Winocur [In: The handbook of aging and cognition, Erlbaum, Hillsdale, NJ, 1992, pp. 315-372] suggest that consciously controlled processes are more dependent on frontal lobe function than are automatic processes. It is appropriate, therefore to determine whether transitions in the locus of primary brain activity occur with practice on mental calculation. In this experiment, we examine the relationship between characteristics of event-related brain potentials (ERPs) and mental arithmetic. Single-digit mental multiplication problems varying in difficulty (problem size) were used, and subjects were trained on these problems for four sessions. Problem-size and practice effects were reliably found in behavioral measures (RT). The ERP was characterized by a pronounced late positivity after task presentation followed by a slow wave, and a negativity during response indication. These components responded differentially to the practice and problem-size manipulations. Practice mainly affected topography of the amplitude of positivity and offset latency of slow wave, and problem-size mainly offset latency of slow wave and pre-response negativity. Fronto-central positivity diminished from session to session, and the focus of positivity centered finally at centro-parietal regions. This finding suggests that frontal lobe processing is necessary as long as task performance is not automatized, while automatized arithmetic processing requires parietal brain activity only. The pre-response negativity observed in the first session and during more difficult tasks is assumed to reflect excitatory preparatory processes, which could be associated with activation of calculation strategies.
No abstract available
No abstract available
The present research examined whether children's awareness of phonological similarities between words with respect to rhyme and consonantal word onset is of the same importance for learning to read German as it was found to be for learning to read English. In two longitudinal studies differences in phonological sensitivity among children before learning to read (at age 6 to 7) were tested with versions of Bradley & Bryant's (1985) oddity detection task. Children's reading and spelling achievements were tested about one year later at the end of grade one, and again at around the age of 10. The main finding was a developmental change in the predictive relationship of rhyme and word-onset awareness. Rhyme awareness was only minimally predictive for reading and spelling achievement at the end of grade one, but gained substantially in predictive importance for reading and spelling achievement in grades three and four. No such predictive improvement was observed for word-onset awareness. It is proposed that rhyme awareness is initially of little importance, because in the first phase of learning to read German children rely heavily on indirect word recognition via grapheme--phoneme translation and blending. The gain in the predictive importance of rhyme awareness is explained by its helpful effect on the establishment of mental representations of written words. Such mental representations allow fast, direct word recognition and orthographically correct spellings. A wareness of larger phonological units is helpful for the efficient establishment of such representations, by allowing connections of recurring grapheme clusters in written words with phonology.
No abstract available