Does “ring syndrome” exist? An analysis of 207 case reports on patients with a ring autosome

Summary Analysis of 207 case reports on patients with ring autosome showed that: (1) Forty patients, a fifth of the total, had extreme growth failure together with an otherwise almost-normal appearance, viz. no major malformation, no specific deletion syndrome, no or only a few unspecific minor anomalies. This phenotype may be regarded as the ring syndrome, a term proposed by Cote et al. (1981) since it is independent of what chromosome is involved. (2) Severe growth failure, the sole major physical abnormality in the ring syndrome, was seen significantly more often among patients with ring of larger chromosomes than among patients with a smaller ring, indicating that the greater the chromosome involved in ring formation, the higher is the probability of severe growth failure. (3) Larger ring chromosomes showed significantly more often instability than smaller rings, suggesting that there may be a correlation between ring instability and the size of the chromosome involved. (4) Growth failure was present in significantly more patients with a labile ring than with a stable ring, indicating that a correlation may exist between ring instability and growth failure. It is suggested that the ring syndrome observed in many cases with ring autosome may result from end-to-end fusion of chromosome ends, an event not involving deletion in the genetic sense. It is also suggested that the ring syndrome is caused by a continuous generation of secondary aneuploid cells with increased mortality, i.e. structural ring instability which seems to be a function of the size of the chromosome involved. Thus, formation of a ring chromosome in certain cases might be regarded as a structural mutation, i.e. an alteration in the structure of the genetic material per se, rather than a loss or gain of genetic dosages.     

Immimocytological localization of a somatostatin-like substance in the brain of the giant slug,Limax maximus L.

Summary Immunocytological tests reveal the presence of a somatostatin-like substance in perikarya and axons in the brain of the giant slug Limax maximus L. Controls carried out on adjacent sections with absorbed antiserum or different antibodies raised against several biologically active peptides of vertebrates (ACTH-17-39, - and endorphin, - and MSH, methionin-enkephalin, TRH) demonstrate the specificity of the staining. However, some cells are both somatostatin- and FMRF-amide-positive. In the cerebral ganglia, the right Z-area cells, responsible for the synthesis of the maturation hormone (MH) are strongly somatostatin-positive. These results suggest a similarity between the MH and the somatostatin-like material contained in the Z-area cells. The simultaneous presence of two peptides in one and the same cell, the nature (elementary granules or soluble product) of the material, and its site of release are discussed.     

In vitro plant regeneration via somatic embryogenesis from root culture of some rhizomatous irises

A method for plant regeneration of Iris via somatic embryogenesis is described. Root and leaf pieces from in vitro-grown plants of several genotypes of rhizomatous Iris sp. were cultured in vitro. Callus induction occurred only on root cultures incubated under low light intensity (35 mol m^-2 s^-1) on two induction media containing 2,4-D (4.5 or 22.5 M), NAA (5.4 M) and kinetin (0.5 M). Somatic embryos developed after transfer of callus onto four regeneration media containing 9 or 22 M BA, or 5 M kinetin and 2 M TIBA or 9 M BA and 4 M TIBA. Plantlets could be obtained from these somatic embryos. Genotypic differences were found both in callus induction and somatic embryo formation, with I. pseudacorus responding better than I. versicolor or I. setosa. Cytological analysis performed on root tips of 80 regenerated plants revealed that two of the I. pseudacorus regenerants were tetraploid.Abbreviations 2,4-D dichlorophenoxy acetic acid - NAA naphthaleneacetic acid - BA 6-benzyladenine - TIBA 2,3,5-triiodobenzoic acid - IBA indolebutyric acid     

Die Brutzeiten einiger Gänsearten und ihrer Bastarde in identischen Bedingungen

Zusammenfassung An Hand von 229 Brutbeginn-Daten von freilebenden Gänsen, die während der Jahre 1956–1966 in Seewiesen (Obb.) (48°N, 11°11E) brüteten, wurden die mittleren Brutbeginn-Daten von 5 Gänsearten und von Artbastarden bestimmt. Es zeigte sich, daß die untersuchten Arten unter diesen Bedingungen in derselben Reihenfolge brüteten, wie ihre Artgenossen in freier Wildbahn. Die mittleren Brutbeginn-Termine wurden allerdings um so mehr vorverlegt, je später die Art normalerweise brütet (Abb. 1). , die mit artfremden verpaart waren, brüteten zur selben Zeit wie ihre Artgenossen, die mit artgleichen verpaart waren (Abb. 1). GraugansxSchneegans-Bastard-, die mit Schneegantern verpaart waren, begannen meist nach den Graugänsen, aber stets vor den Schneegänsen zu brüten (Abb. 1, 2). Das intermediäre Brüten dieser wird als starkes Argument für die Richtigkeit der Hypothese gewertet, nach welcher die artspezifisch verschiedenen Brutzeiten wenigstens zum Teil genetisch bedingt sind. In der Diskussion wird die Frage kritisch erörtert, wie weit schon allein die Tatsache, daß die verschiedenen Arten über Generationen hinweg in derselben Reihenfolge wie ihre wildlebenden Artgenossen zu brüten beginnen, als Beweis für derartige genetische Unterschiede angesehen werden kann.

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Summary In 229 cases onset of breeding was recorded from free-living geese of 5 species and of some hybrids of these species, kept in Seewiesen/Obb. (48° N, 11° 11E) from 1956 to 1966. It was found that the species under these conditions bred in the same seasonal sequence as did wild birds. The mean breeding times, however, were found to be advanced in relation to the onset of breeding in the wild (Fig. 1). This was especially evident in the case of late-breeding species. paired with of another species came into breeding condition at the same time as paired with of the same species (Fig. 1). GraylegxSnowgoose hybrid paired with Snowgoose in most cases started to breed later than Greyleg geese but always earlier than the mean breeding time for Snowgeese (Fig. 1, 2). This intermediate breeding time is taken as a strong argument for the hypothesis that the species specific differences in breeding times are, at least in part, genetic in origin. The question as to the extent to which the differences in breeding times alone, persisting for generations in the same sequence as those of wild birds, can be attributed to genetic differences between the species, is critically discussed.

     

Effect of chronic desipramine treatment on neurotransmitter-thyrotropin releasing hormone—thyrotropin interactions in the rat

Long-term administration of the antidepressant drug, desipramine (20 mg/kg/day, orally for 28 days), decreased the stimulatory effect of the ₂-adrenoceptor agonist, clonidine (250 g/kg, i.p.) on thyrotropin (TSH) secretion in the rat, but did not alter basal TSH secretion. -Adrenoceptor-mediated inhibition of TSH secretion by isoproterenol (1 mg/ kg, i.p.) was unaffected by chronic desipramine treatment, as were the stimulatory effect of TSH-releasing hormone (TRH, 5 g/kg, i.v.) on TSH release and its inhibition by the -adrenoceptor antagonist, phentolamine (2 mg/kg, i.p.). These findings suggest that chronic desipramine treatment induces subsensitivity of ₂-adrenoceptors which modulate TSH secretion in the rat while not affecting -adrenoceptor-mediated inhibition of TSH release. These findings suggest that pituitary TRH receptors are unchanged but that changes occurred at the hypothalamic level in ₂-adrenoceptor-mediated stimulation of TRH release. Although cerebral -adrenoceptors have been shown convincingly to be down-regulated after chronic desipramine treatment, their function in the hypothalamic TRH system after 28 days of treatment with desipramine appears to be unimpaired.     

Uptake of sewage derived nitrogen by<Emphasis Type="Italic"> Ulva rigida</Emphasis> (Chlorophyceae) in Bahía Nueva (Golfo Nuevo,Patagonia, Argentine)

Uptake kinetics of nitrogen derived from sewage–seawater mixtures (2.5–20% v/v effluent) were determined in the laboratory for Ulva rigida (Chlorophyceae) native from Bahía Nueva (Golfo Nuevo, Patagonia, Argentine). In terms of nitrogen concentration, experimental enrichment levels varied between 53.7 and 362.3M of ammonium and between 0.77 and 6.21M of nitrate+nitrite. Uptake rates were fitted to the Michaelis–Menten equation, with the following kinetic parameters: ammonium: V_max = 591.2molg^–1h^–1, K _s=262.3M, nitrate+nitrite: V _max=12.9molg^–1h^–1, K _s=3.5M). Both nutrients were taken up simultaneously, but ammonium incorporation was faster in all cases. The results show a high capability of Ulva rigida to remove sewage-derived nitrogen from culture media. In the field, most of the nitrogen provided by the effluent would be tied up in algal biomass, supporting low nitrogen levels found at a short distance away from the source.     

Regional distribution of membrane-bound γ-glutamyl transpeptidase activity in mouse brain

Activity of membrane-bound -glutamyl transpeptidase (-GTP) was examined in various regions of mouse brain, in capillaries of the cerebral cortex and in telencephalic choroid plexuses. The level of activity in the capillaries was double and that of the choroid plexus nine times that of the -GTP activity found in the brain, septum, hippocampus, hypothalamus, thalamus, cerebellum, frontal cortex, pons, medulla oblongata, and amygdala. Histochemically the -GTP activity was demonstrated in the surface membranes of choroidal cells and in the endothelium of small capillaries.The activities of -GTP of cerebral cortex, choroid plexus, and capillaries from rabbit were 5–17 times greater than those from corresponding areas of mouse brain. While 30 mM methionine stimulated (in vitro) the enzyme from mouse brain, no such effect was observed with the enzyme activity from rabbit brain. The -GTP activity from the capillaries of cerebral cortex of both mouse and rabbit was not effected by the presence of methionine.These findings suggest existence of differences in the specificity of -GTP activity in these two species.     

A model of associative memory in the brain

A model of associative memory for time varying spatial patterns is proposed and simulated on a digital computer. This is a network composed of many neuron-like elements, and shows an ability for associative memory similar to that of the brain.Suppose a number of sequences of spatial patterns are presented to this network, for example, 12345, ABC, and so on. Then, these patterns are memorized in the network. After that, if any part of one of these sequences, say 23, is presented to the circuit, the rest of the sequence, 45, is recalled following to it. It resembles to such a situation — if we hear a part of a melody which we have memorized in the past, the rest of the melody is recalled even after it is stopped half-way. Although the recalled patterns are not always 100% correct, they are not completely destroyed even if the presented patterns are imperfect.     

The structure of the incompatibility factors of Schizophyllum commune: Constitution of the three classes of B factors

Summary The B factors of Schizophyllum commune are of 3 classes: The high recombining class I has 7 alleles and 7 alleles; the low recombining classes are class II with 7 allels and probably 2 alleles and class III with probably 2 (or also 2) alleles and 7 allels. A fourth hypothetical class (-) was not found and either does not exist or is indistinguishable from class III by the tests employed. The and alleles differ from and by either (a) mutations affecting both mating specificity and recombination frequency, or (b) deletions involving most of the B region.The research was supported by a grant from the Atomic Energy Commission of the U.S. No. (30-1)-3875 and was performed at the Biological Laboratories, Harvard University, Cambridge, Mass., U.S.A.     

Utilization and degradation of lindane by soil microorganisms

Of 147 microorganisms isolated from a loamy sand, 71 showed good growth with lindane (-1,2,3,4,5,6-hexachlorocyclohexane) and produced chloride in an aqueous medium. Thirteen soil microorganisms were selected to study the utilization of lindane. Lindane was metabolized by the microbes to -2,3,4,5,6-pentachloro-1-cyclohexene (-PCCH), -3,4,5,6-tetrachloro-1-cyclohexene (-TCCH), -3,4,5,6-tetrachloro-1-cyclohexene (-TCCH), -3,4,5,6-tetrachloro-1-cyclohexene (-TCCH), and pentachlorobenzene (PCB). Cells of Pseudomonas sp. No. 62 grown on lindane simultaneously adapted to -PCCH, -TCCH, -TCCH, -TCCH, PCB, 1,2,3,4-tetrachlorobenzene (1,2,3,4-TCB) and 1,2,4,5-tetrachlorobenzene (1,2,4,5-TCB). The bacteria degraded each of these chemicals at least partially as indicated by an increased rate of oxygen consumption.Abbreviations Lindane -1,2,3,4,5,6-hexachlorocyclohexane - -PCCH -2,3,4,5,6-pentachloro-1-cyclohexene - -TCCH -3,4,5,6-tetrachloro-1-cyclohexene - -TCCH -3,4,5,6-tetrachloro-1-cyclohexene - -TCCH -3,4,5,6-tetrachloro-1-cyclohexene - PCB pentachlorobenzene - 1,2,3,4-TCB 1,2,3,4-tetrachlorobenzene - 1,2,3,5-TCB 1,2,3,5-tetrachlorobenzene - 1,2,4,5-TCB 1,2,4,5-tetrachlorobenzene - 1,2,3-tCB 1,2,3-trichlorobenzene - 1,2,4-tCB 1,2,4-trichlorobenzene - 1,3,5-tCB 1,3,5-trichlorobenzene - 1,2-DCB 1,2-dichlorobenzene - 1,3-DCB 1,3-dichlorobenzene - 1,4-DCB 1,4-dichlorobenzene - MCB monochlorobenzene Contribution No. 631, Research Institute, Agriculture Canada, University Sub Post Office, London, Ontario N6A 5B7     

Neuronal responses in the tectum opticum ofSalamandra to visual prey stimuli

Summary In the tectum opticum ofSalamandra salamandra neurons were recorded that showed different selectivity to visual prey stimulus parameters. 21 of 80 neurons responded stronger to rectangles oriented horizontally (wormlike configuration) than to the same patterns oriented vertically. With increasing stimulus velocity, however, these neurons showed non-uniform response characteristics. Although there are partial similarities between behavior and neuronal activity, no response curve of tectal neurons corresponds strictly to response curves of salamander preycapture behavior. So none of the neuron types can be called a prey detector.Supported by the Deutsche Forschungsgemeinschaft     

Enzymatic basis for sialyl-Tn expression in human colon cancer cells

Sialyl-Tn antigen (SA2-6 GalNAc-Ser/Thr) is expressed as a cancer-associated antigen on the surface of cancer cells and its expression correlates with a poor prognosis in patients with colorectal and other adenocarcinomas. To understand the enzymatic basis of sialyl-Tn (STn) antigen expression, we used two clonal cell lines, LSB and LSC, derived from LS174T human colonic cancer cells. LSC cells express only the truncated carbohydrate antigen Tn (GalNAc-Ser/Thr) and sialyl-Tn on their mucin molecules, whereas LSB cells express elongated oligosaccharide chains. Both cell lines demonstrated similar activities of glycosyltransferases involved in the biosynthesis of elongated and terminal structures of complex O-glycans. However, LSC cells were unable to synthesize core 1 (Gal1-3GalNAc-) because the ubiquitous enzyme activity of UDP-Gal:GalNAc-R 3-Gal-transferase (core 1 3-Gal-transferase) was lacking. Core 1 3-Gal-transferase could not be reactivated in LSC cells by treatment with sodium butyrate or by in vivo growth of LSC cells in nude mice. In contrast, LSB cells were able to synthesize and process core 1 and core 2 (GlcNAc1-6 (Gal1-3) GalNAc-). LSC cells represent the first example of a non-hematopoietic cell line which lacks core 1 3-Gal-transferase activity. The lack of core 1 3-Gal-transferase in LSC cells explains why they are incapable of forming the common mucin O-glycan core structures and are committed to synthesizing the short Tn and STn oligosaccharides. These findings suggest that the activity of core 1 3-Gal-transferase is an important determinant of the STn phenotype of colon cancer cells.     

Cryptomonad biliproteins: Bilin types and locations

Two crytophycean phycocyanins (Cr-PCs), Hemiselmis strain HP9001 Cr-PC 612 and Falcomonas daucoides Cr-PC 69 were purified and characterized with respect to bilin numbers, types and locations. Each biliprotein carried one bilin on the subunit and three on the subunit. Cr-PC 612 carried phycocyanobilin at -Cys-18, -Cys-82, and -Cys-158, and a doubly-linked 15,16-dihydrobiliverdin at -DiCys-50,61. Cr-PC 569 carried phycocyanobilin at -Cys-18 and -Cys-82, a singly-linked Bilin 584 at -Cys-158, and a doubly-linked Bilin 584 at -DiCys-50,61. This work, in conjunction with earlier studies on Cr-PE 545, Cr-PE 555, Cr-PE 566, and Cr-PC 645, shows that there is no conserved location for the bilin with longest wavelength visible absorption band among these proteins, and, consequently, that there is no conserved energy transfer pathway common to all native cryptophycean biliproteins. Only phycocyanobilin or phycoerythrobilin is found at -Cys-82; there is greater bilin variability at the other three attachment sites.Abbreviations Cr-PC cryptophycean phycocyanin - Cr-PE cryptophycean phycoerythrin - DBV 15,16-dihydrobiliverdin - MBV mesobiliverdin - PCB phycocyanobilin - PEB phycoerythrobilin - HPLC high performance liquid chromatography - TFA trifluoroacetic acid     

Abscisic acid as an endogenous component in lettuce fruits,Lactuca sativa L. cv. Grand Rapids. Does it control thermodormancy?

Summary Abscisic acid (ABA) has been unequivocally identified as an endogenous component of seeds of Grand Rapids lettuce. Both free and bound ABA levels were followed during imbibition at various temperatures but no clear role for ABA in the imposition of thermodormancy emerged. Furthermore it was apparent that different seed batches showed different ratios of free to bound ABA and patterns of changes. An unsuccessful attempt was made to identify bound ABA, presumed to be the glucosyl ester.Abbreviations ABA abscisic acid - ABA Me ester methyl abscisate - ECD electron capture detector - FID flame ionisation detector - GC-MS combined gas liquid chromatography, mass spectrometry - GLC gas liquid chromatography - PVP polyvinyl-pyrrolidone - TLC thin layer chromatography     

The chromosomal localization of human β-galactosidase revisited: a locus for β-galactosidase on human chromosome 3 and for its protective protein on human chromosome 22

Summary A series of man-Chinese hamster and man-mouse somatic cell hybrids was investigated to study the localization of the genes coding for the human lysosomal enzyme -galactosidase (EC 3.2.1.23) and for its protective protein. Using a monoclonal antibody, raised against human placental -galactosidase, it was observed that the structural locus for the -galactosidase polypeptide is located on chromosome 3. The nature of the involvement of chromosome 22 in the expression of human -galactosidase was elucidated by metabolic labelling of the hybrids with radioactive amino acids, immunoprecipitation with monoclonal and polyclonal antibodies against -galactosidase, followed by analysis via gel electrophoresis and fluorography.The data show that the presence of chromosome 22 coincides with the presence of a 32 kd protein. This polypeptide, the protective protein was previously shown to be intimately associated with human -galactosidase. In addition, the protective protein was found to be essential for the in vivo stability of -galactosidase by aggregating -galactosidase monomers into high molecular weight multimes. Both chromosome 3 and 22 are therefore necessary to obtain normal levels og -galactosidase activity in human cells.     

Laboratory culture studies of Trichodesmium isolated from the Great Barrier Reef Lagoon, Australia

Cultures of Trichodesmium from the Northern and Southern Great Barrier Reef Lagoon (GBRL) have been established in enriched seawater and artificial seawater media. Some cultures have been maintained with active growth for over 6years. Actively growing cultures in an artificial seawater medium containing organic phosphorus (glycerophosphate) as the principal source of phosphorus have also been established. Key factors that contributed to the successful establishment of cultures were firstly, the seed samples were collected from depth, secondly, samples were thoroughly washed and thirdly, incubations were conducted under relatively low light intensities (PAR 40–50molquantam^–2s^–1). N₂ fixation rates of the cultured Trichodesmium were found to be similar to those measured in the GBRL. Specific growth rates of the cultures during the exponential growth phase in all enriched media were in the range 0.2–0.3day^–1 and growth during this phase was characterised by individual trichomes (filaments) or small aggregations of two to three trichomes. Characteristic bundle formation tended to occur following the exponential growth phase, which suggests that the bundle formation was induced by a lack of a necessary nutrient e.g. Fe. Results from some exploratory studies showed that filament-dominated cultures of Trichodesmium grew over a range of relatively low irradiances (PAR 5–120molquantam^–2s^–1) with the maximum growth occurring at 40–50molquantam^–2s^–1. These results suggest that filaments of the tested strain are well adapted for growth at depth in marine waters. Other studies showed that growth yields were dependent on salinity, with maximum growth occurring between 30 and 37psu. Also the cell yields decreased by an order of magnitude with the reduction of Fe additions from 450 to 45nM. No active growth was observed with the 4.5nM Fe addition.     

βs Haplotypes in various world populations

Summary We have determined the ^s haplotypes in 709 patients with sickle cell anemia, 30 with SC disease, 91 with S--thalassemia, and in 322 Hb S heterozygotes from different countries. The methodology concerned the detection of mutations in the promoter sequences of the ^G- and ^A-globin genes through dot blot analysis of amplified DNA with ³²P-labeled probes, and an analysis of isolated Hb F by reversed phase high performance liquid chromatography to detect the presence of the ^AT chain [^A75 (E19) IleThr] that is characteristic for haplotype 17 (Cameroon). The results support previously published data obtained with conventional methodology that indicates that the ^s gene arose separately in different locations. The present methodology has the advantage of being relatively inexpensive and fast, allowing the collection of a vast body of data in a short period of time. It also offers the opportunity of identifying unusual ^s haplotypes that may be associated with a milder expression of the disease. The numerous blood samples obtained from many SS patients living in different countries made it possible to compare their hematological data. Such information is included (as average values) for 395 SS patients with haplotype 19/19, for 2 with haplotype 17/17, for 50 with haplotype 20/20, for 2 with haplotype 3/3, and for 37 with haplotype 31/31. Some information on haplotype characteristics of normal ^A chromosomes is also presented.     

Die Hemmung der Phytochrominduzierten Photomorphogenese („Positive” Photomorphosen) des Senfkeimlings (Sinapis alba L.) Durch Actinomycin D und Puromycin

Zusammenfassung Die positiven Photomorphosen Öffnung des Hypokotylhakens und Entfaltung der Kotyledonen können ganz ähnlich wie die phytochrominduzierte Anthocyansynthese und andere positive Photomorphosen durch Actinomycin D und Puromycin gehemmt werden. Man kann daraus schließen, daß diese beiden photomorphogenetischen Reaktionen des Senfkeimlings ebenfalls durch eine von P₇₃₀ über eine Signalkette ausgelöste Aktivierung von potentiell aktiven Genen veranlaßt werden.

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The inhibition of phytochrome-mediated photomorphogenesis (positive photoresponses) by actinomycin D and puromycin in the mustard seedling (Sinapis alba L.)

Summary The many photochrome-mediated photoresponses of a seedling (Sinapis alba L., white seeded mustard) can be divided into 3 categories: positive, negative, and complex photoresponses. Positive photoresponses are those which are characterized by an initiation or a promotion of biosynthetic or growth processes (Mohr, 1966b). Phytochrome-mediated anthocyanin synthesis is the prototype of a positive photoresponse. It has been shown in previous papers (e.g. Lange and Mohr, 1965; Mohr et al., 1965) that positive photoresponses can be specifically inhibited by actinomycin D and puromycin. It has been concluded that in the case of positive photoresponses P₇₃₀ (the active phytochrome) exerts its function through differential gene activation.—In the present paper it has been demonstrated that phytochrome-mediated positive photoresponses of the mustard seedling like opening of the hypocotylar hook and unfolding of the cotyledons can be inhibited by relatively low doses of actinomycin D and puromycin in very much the same way as anthocyanin synthesis or cotyledon enlargement is inhibited. It has been concluded that in these cases too the action of P₇₃₀ must be attributed to an activation of potentially active genes in the manner postulated on the basis of the data on anthocyanin synthesis.

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Die Arbeit wurde durch Sachbeihilfen der Deutschen Forschungsgemeinschaft und der Stiftung Volkswagenwerk (an Prof. Mohr) ermöglicht.     

Ethnocentricity and the social construction of ‘mass hysteria’

This study provides a critical historical review and analysis of the variety of human expressions which have been erroneously labeled under the grandiose category mass hysteria. It is argued that Western science reductionist approaches to the classification of mass hysteria treat it as an entity to be discovered transculturally, and in their self-fulfilling search for universals systematically exclude what does not fit within the autonomous parameters of its Western-biased culture model, exemplifying what Kleinman (1977) terms a category fallacy. As a result of objectivist methodologies, the etiology of actions labeled as mass hysteria is typically viewed as deviant, irrational or abnormal behavior resulting from a malfunctioning proper social order. However, what constitutes the correct social order is a function of a researcher's historical sociocultural and/or scientific milieu. This study reviews the problem, advocating Geertz's (1973) culturally relativistic approach to understanding various cross-cultural behavior that is sensitive to and tolerant of the unique context and milieu of participants. Mass or epidemic hysteria is viewed as an invention of Western psychiatry and should be abandoned and replaced with the term collective exaggerated emotions. Instead of attempting to discover a neatly packaged, unitary external disease entity, the focus of a meaning-oriented approach emphasizes the deciphering of foreign realities, semantic networks and symbol systems.     

Human pattern recognition: Evidence for a switching between strategies in analyzing complex stimuli

In a preceding multidimensional scaling experiment, with size and brightness as parameters, subjects were found to use individually different strategies in processing compound stimuli: Most subjects adhered to either the Euclidean or the City-block metric (Ronacher and Bautz, 1985). In the experiment reported here, participants of the previous study were induced-by a manipulative instruction-to modify their strategy. With 5 out of 10 subjects a switching to another strategy occurred, which manifested itself in a drastic shift of the respective best metric (e.g. from Euclidean to City-block or vice versa). The extent and speed of changes as well as-in some instances-the stability of estimation accuracy show that subjects were not forced by the instruction to develop a new strategy. Results rather suggest that adult subjects have easily available two, or perhaps even more, alternative processing modes, the decision for one of them being a matter of a subject's preferences rather than of individually different abilities.