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At least 19 recordsLinked to original sources
PubMed1979

Multivariate behavioral genetic analysis of twin data on scholastic abilities.

Multivariate behavioral genetic analyses may employ either genetic and environmental correlations or phenotypically standardized covariances to assess the structure of genetic and environmental influences. Correlations and phenotypically standardized covariances answer different questions--correlations are appropriate for understanding the nature of genetic and environmental influences, whereas covariances are appropriate for determining the etiology of phenotypic correlations. The ratio of the genetic and environmental covariances to the phenotypic correlation yields estimates of bivariate heritability and environmentality, measures of the extent to which observed phenotypic covariance is due to genetic and environmental influences. Multivariate analyses of genetic and environmental correlations and covariances are illustrated with twin data on scholastic abilities. Factor analyses of correlations suggest that the same set of genes affects the major areas of academic achievement and that the environmental influences are similarly structured. Analyses of phenotypically standardized covariances indicate that the structures of genetic and environmental influences as they contribute to phenotypic resemblance among scholastic abilities are both similar and simple: there are one general genetic factor and one general environmental factor. Bivariate heritabilities and environmentalities are similar in magnitude, indicating that the strong phenotypic relationship among scholastic abilities is due roughly equally o genetic and environmental influences.

Analysis of Variance↗
PubMed1979

The electroencephalogram (EEG) as a research tool in human behavior genetics: psychological examinations in healthy males with various inherited EEG variants. II. Results.

The results of psychological examinations on 298 adult male probands with various inherited EEG variants are described. They may be summarized as follows: 1) The low-voltage (N) group scored high in intelligence tests, especially in spatial orientation. Personality scores revealed this group as 'normal', extravert, group-dependent, and not very energetic. 2) The borderline low-voltage (NG) group showed slight weakness in abstract thinking, short-time memory, and motor skills and a relatively strong tendency to have 'neurotic' complaints. Reaction time and motor skills were poor. 3) The occipital fast alpha-variants (BO) group performed very well in tests of abstract thinking and motor skills. 4) The monotonous alpha (R) group showed average performance in most intelligence scores but above-average in short-time memory and in precision under stress conditions. Personality scores indicated high spontaneous activity and toughmindedness. 5) The BG (fronto-precentral beta-group) category showed very low MMPI scores, indicating little neurotic tendency. Intelligence could be above average. 6) The diffuse beta (BD) group scored low in intelligence tests, especially in spatial orientation, and had a high error rate in tests measuring concentration and precision. Most differences were relatively small; the whole range of test scores could be found in all EEG groups.

Adult↗
PubMed1979

The electroencephalogram (EEG) as a research tool in human behavior genetics: psychological examinations in healthy males with various inherited EEG variants. III. Interpretation of the results.

Interpretation of the results from psychological examinations of 298 probands with inherited EEG variants requires (1) critical evaluation of previous literature on psychological EEG correlates, (2) knowledge of the main concepts and experimental approaches for elucidating the basic mechanisms of EEG rhythms, (3) discussion of previous attempts to link psychological variation in human populations with corresponding variation in brain function, and (4) interpretation of results from considerations at these three levels with the data from our own study. At the first level (previous psychological studies), comparison with Schmettau's study proved to be especially revealing: Her conclusions about personality correlates with high alpha-index and with "flat" EEGs were very similar to ours with the monotonous alpha- (R) and low-voltage (N) EEGs, respectively. Her EEG type with high beta-index overlaps with our beta-diffuse (BD) type; a tendency to psychasthenia and low resistance to stress is less obvious in our group, but is expressed indirectly by reduced speed and accuracy in tests requiring attentiveness and persistence. The correlation between alpha-frequency and intelligence found in other studies was confirmed by the especially high intelligence scores of our group with occipital fast alpha-variants (BO). At the second and third levels of the discussion (EEG mechanisms; neurophysiological theories), the cooperation of cerebral cortex (EEG battery), thalamus (pacemaker), and ARAS (tonic arousal) is discussed, and the personality typologies of Eysenck and Claridge are mentioned. From this and other evidence, the following hypotheses are discussed: 1) The personality profiles of the R group are influenced by high activity and efficiency of the thalamic alpha-pacemaker(s), which leads to a high degree of modulation, selection, and amplification of afferent stimuli. 2) In the countertype of this EEG variant, the N EEG, a low modulation and amplification by the thalamic alpha-pacemaker is assumed. This leads to relatively low intensity of feeling and to low spontaneous activity, but to faster information processing. Combined with an increased level of tonic arousal in the ARAS, it may cause certain 'neurotic' complaints (our low-voltage borderline (NG) group). 3) The EEG with diffuse beta-waves (BD) is caused by a high level of tonic arousal in the ARAS, which tends to distrub the thalamocortical circuit. This leads to reduced stress resistance and to impairment of intellectual functions, especially space perception. Due to limited evidence, the next two hypotheses are advanced only tentatively: 4) alpha-rhythm with very high frequency 16--19 c/s) leads to improvement of information processing and, hence, to high intellectual performance and motor dexterity. 5) Probands with frontoprecentral beta-groups (BG) show no psychological signs of increased tonic arousal; therefore, these beta-groups are caused not by increased tonic arousal of the ARAS, but by a genetic variant of a thalamic subsystem.

Adult↗
PubMed1976

Twin studies and behavior genetics.

It is observed that neither the methodology of twin studies nor that of behavior genetics in general has been adequately explored in most investigations of human behavior. General distrust of genetic methodologies as well as the belief that genic disorders are unalterable appear to be salient factors in explaining the neglect of those areas by social scientists. A plea is made for putting aside biased attitudes that prevent utilization of the best available techniques for the study of human beings as distinguished from all other animals.

Attitude↗
PubMed1979

The electroencephalogram (EEG) as a research tool in human behavior genetics: psychological examinations in healthy males with various inherited EEG variants. I. Rationale of the study. Material. Methods. Heritability of test parameters.

In the first section of this paper, various research designs in human behavior genetics are compared. In this context, the commonly used concept of biometric genetics is critically evaluated from the point of view of science theory. It is contrasted with the Mendelian gene concept, which, in principle, leads to a much deeper theoretical understanding by offering clues for basic mechanisms. To explore this advantage fully, a research strategy is needed that first looks for genetic variability in a physiological parameter of possible importance for human behavior and then tries to explore the influence of this parameter on the function of the human brain and on behavior. If possible, this genetic parameter should be selected in a way that inferences as to the mechanism of its influence on behavior become feasible. Such genetic variability is provided by the hereditary variants of the normal EEG discovered by earlier work (cf. Vogel, 1970). In the following section, a research program on 298 adult healthy males, most of them soldiers, with various inherited EEG variants is described. Apart from controls with inconspicuous EEGs, this material comprises probands with the following EEG variants: low-voltage (N); low-voltage borderline (NG); monotonous alpha-waves (R); occipital fast alpha-variants (BO); fronto-precentral beta-groups (BG), and diffuse beta-waves (BD). In addition to an EEG examination, the probands were examined with various test methods measuring intelligence (IST; LPS; Raven); working speed and concentration (d-2; KLT); personal attitudes (MMPI; 16PF; RKS); and sensory and motor abilities (flicker fusion; tachistoscopy; reaction time to optic, acoustic and combined stimuli; two-hand dexterity; pursuit rotor; tapping). In a supplementary twin study on 52 male adult twin pairs (26 MZ, 26 DZ), heritabilities were determined for the test scores included in the main study. For most test scores, heritabilities are relatively low; the data are compared with those from the literature. We conclude that the test methods utilized in the main study (on EEG variants) are expected to demonstrate at the most a small to moderate correlation of the EEGs with psychological phenotypes as defined by test examinations, even if a major part of the genetic variability underlying these phenotypes would be due to differences in brain physiology that could be revealed by EEG variation.

Adult↗
PubMed1978

Monogene inheritance of learning speed in DBA and C3H mice. A behavioral genetic study in the shuttle-box.

We carried out investigations on C3H, NMRI, C57Bl/6, Balb/c, Balb/cN, and DBA inbred mouse strains in the shuttle-box to see whether their learning behavior is genetically controlled. The highly different learning behavior of the parental strains made it possible to test the F1 hybrids and the F2 generation. The environmental influences were standardized as much as possible. In particular, influences possible during the lactation period were excluded by using foster breeding. The results enable us to postulate monogenic inheritance for the learning speed in the shuttle-box. The inheritance is interpreted as codominant. The investigations are part of a basic study in mammalian behavior genetics from the human genetic aspect.

Animals↗
PubMed1977

Behavior-genetic analysis of Phormia regina: conditioning, reliable individual differences, and selection.

Using proboscis extension (unconditioned response) to sucrose (unconditioned stimulus), individual blowflies (Phormia regina) were classically conditioned to saline and to water (conditioned stimuli) with sensitization controls, thus providing unique, independently replicated evidence both of learning in Diptera and of reliably measured individual differences. Directional and stabilizing selection have bred high and low performance lines markedly different from an unselected control line as a step in the analysis of behavior-genetic correlates. This replicates and extends previous selection analysis with improved conditioning technique. Also, some unwarranted claims of learning in Diptera are discussed.

Animals↗
PubMed1975

Behavior genetic analysis of mouse emotionality. III. The diallel analysis.

A total of 775 pure-strain and F1 mice were obtained from a 6 X 6 diallel mating plan. Previous factor analysis of 42 measures of emotionality identified 14 behavioral factors, ten of which were interpretable. Hayman's analysis of variance and analysis of diallel crosses were applied to each of the factors. In general, the findings indicate that the mode of inheritance for emotionality factors is polygenic and in the direction of complete dominance. However, a major point of this investigation is that the mode of inheritance of highly complex behavior such as emotionality depends on the factor in question. For example, the breakdown of dominance effects by factor was as follows: partial dominance--Motor Discharge, Food Motivation, Tunneling-2, and Activity Level (males); complete dominance--Audiogenic Reactivity, Underwater Swimming (males), and Activity Level (females); overdominance--Acrophobia, Territorial Marking (males). Additional findings include directional dominance for Underwater Swimming and Audiogenic Reactivity, and significant sex differences for eight of the 14 factors.

Animals↗
PubMedDate not supplied

Circular countercurrent-distribution behavioral genetic maze.

An inexpensive, easily constructed apparatus for mass screening of taxes of small animals with a rapid and accurate assignment of individual behavior scores has been described that should be of utility in hastening a behavioral geneticist's chores and allow him to handle more populations with fewer mazes. Also, the apparatus is well suited for use within the constraints of the undergraduate laboratory.

Animals↗
PubMed1975

Avoidance learning, behavior genetics, and aging: a critical review and comment on methodology.

Animal models of human aging problems are potentially of enormous value to gerontological research. Models of behavioral problems have not often lived up to their promise. This review examines one such model system, avoidance learning in aging rodents. This model system has become increasingly popular among behavioral gerontologists, yet it has not provided the unambiguous answers to experimental questions which investigators expected. Our effort has been to determine why the system has failed, and to provide useful suggestions for future research. At the same time we have tried to provide a comprehensive review of the relevant literature and to assess the strengths and weaknesses of studies which have been conducted in the last two decades.

Adult↗