The discrepancy between current and premorbid ability is a relevant indicator of acquired mental impairment, which itself is closely related to general cerebral dysfunction. The use of tests sensitive to cerebral dysfunction, raises relatively few problems compared with tests being resistant that are used to estimate premorbid mental ability. For premorbid ability, verbal tests assessing knowledge, especially vocabulary, have been shown to be valid. A test, possibly more insensitive to brain dysfunction than the ones usually administered, is the multiple choice vocabulary test (MWT = Mehrfachwahl-Wortschatz-Test). At present only German versions are available. They are presented in some detail because of their advantages. Construction of the MWT is simple, and it can be easily administered in about five minutes. The results correlate fairly well with global IQ in healthy adults (median of r = 0.72 in 22 samples) and are more insensitive to current disturbances than such tests as the WAIS vocabulary test. The limitations of premorbid tests with respect to diagnostic validity are discussed. It is concluded, that studies which do not control premorbid intelligence have to be considered as a "malpractice" and should not be accepted by scientists.

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Adherents oj" the Galton paradigm favour the concept that the simple parameter 'speed of information processing' has a physiological basis and determines complex achievements assessed in intelligence tests as well as social success. These assumptions are supported by inter-individual correlations. Further supporting evidence comes from total measurement where not only the information content of the stimuli is measured, but also the time to process them. This reveals an individually constant period during which 1 bit of information is processed. It is called the 'basic period of information processing' (BIP), which lasts 1/15s (= 67ms) in average adults (IQ 100) and is constant over the ranges from which target stimuli can be drawn and over varying modes of the signs (letters, numbers, musical notes, etc. ). In representative samples of adults duration of BIP correlatos with global ZQ (r = -0.60): We conclude that the BIP of an adult with an IQ of I22 is 50ms and with an ZQ of 78 twice as long (looms). We consider BIP to be a physiological and general determinant of intelligence, being measurable at a ratio or even an absolute scale level. Thus, it appears to be suitable as a building unit for reconstructing the rather fuzzy traditional concept of general intelligence.

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