Habitual starvation and provocative behaviors: Two potential routes to extreme suicidal behavior in anorexia nervosa

Anorexia nervosa (AN) is perhaps the most lethal mental disorder, in part due to starvation-related health problems, but especially because of high suicide rates. One potential reason for high suicide rates in AN may be that those affected face pain and provocation on many fronts, which may in turn reduce their fear of pain and thereby increase risk for death by suicide. The purpose of the following studies was to explore whether repetitive exposure to painful and destructive behaviors such as vomiting, laxative use, and non-suicidal self-injury (NSSI) was a mechanism that linked AN-binge-purging (ANBP) subtype, as opposed to AN-restricting subtype (ANR), to extreme suicidal behavior. Study 1 utilized a sample of 787 individuals diagnosed with one or the other subtype of AN, and structural equation modeling results supported provocative behaviors as a mechanism linking ANBP to suicidal behavior. A second, unexpected mechanism emerged linking ANR to suicidal behavior via restricting. Study 2, which used a sample of 249 AN patients, replicated these findings, including the second mechanism linking ANR to suicide attempts. Two potential routes to suicidal behavior in AN appear to have been identified: one route through repetitive experience with provocative behaviors for ANBP, and a second for exposure to pain through the starvation of restricting in ANR.     

Temporal discrimination as a function of marker duration

In a series of three experiments, the effect of marker duration on temporal discrimination was evaluated with empty auditory intervals bounded by markers ranging from 3 to 300 msec or presented as a gap within a continuous tone. As a measure of performance, difference thresholds in relation to a base duration of 50 msec were computed. Performance on temporal discrimination was significantly better with markers ranging from 3 to 150 msec than with markers ranging from 225 to 300 msec or under the gap condition. However, within each range of marker duration (3–150 msec; 225–300 msec or gap) performance did not differ significantly. A fourth experiment provided evidence that the effect of marker duration cannot be explained in terms of marker-induced masking. A good approximation of the relationship between marker duration and temporal discrimination performance in the present experiments is a smooth step function, which can account for 99.3% of the variance of mean discrimination performance. Thus, the findings of the present study point to the conclusion that two different mechanisms are used in the processing of temporal information, depending on the duration of the auditory markers. The tradeoff point for the hypothetical shift from one timing mechanism to the other may be found at a marker duration of approximately 200 msec.     

Ontogenese des Verhaltens von Totenkopf-Affen (Saimiri sciureus)

Zusammenfassung Zehn Totenkopf-Affenkinder, die in gemischten Gruppen aufwuchsen, wurden in einer Verlaufsuntersuchung über 1200 Std beobachtet. Die Ontogenese des Verhaltens von der Geburt bis ins vierte Lebensjahr hinein wird in sieben Phasen beschrieben. Neben der Mutter-Kind-Beziehung wird vor allem die Beziehung zwischen Kind und Gruppe berücksichtigt.Während des ersten Lebensmonats ist die Mutter-Kind-Beziehung überwiegend taktil gelenkt. Interaktionen des Säuglings mit Gruppenmitgliedern gibt es schon vom ersten Lebenstag an. Von der dritten Woche an entsteht die sog. Tante-Kind-Beziehung, eine enge, meist vielseitige Bindung zwischen dem Kind und einem Weibchen.Wenn das Kind im zweiten Lebensmonat motorisch selbständig wird, entwickelt sich eine stärker visuell orientierte Beziehung zur Mutter. Zugleich setzt die Entwöhnung ein, und das Kind erweitert die schon bestehenden sozialen Bindungen um die Spielpartner-Beziehung. Ein großer Teil der arttypischen Verhaltensweisen ist bis zu diesem Zeitpunkt aufgetreten.Mit 5 und mit 9 Monaten lockert sich die Mutter-Kind-Beziehung jeweils stufenweise. Gleichzeitig treten neue Verhaltensmuster auf, und andere Verhaltensweisen verändern sich in der Häufigkeit und im Kontext ihres Auftretens.Im letzten Entwöhnungsabschnitt vom 9. bis zum 14. Monat tritt das junge Männchen in Beziehung zum ranghöchsten Tier der Gruppe; diese Beziehung umfaßt Kampfspiele und allmählich zunehmende Unterdrückung während des zweiten und dritten Jahres, bis sie mit Erreichen der Geschlechtsreife im Alter von 2 Jahren und 9 Monaten in Rivalenkämpfe übergeht.Das Verhalten entwickelt sich aus angeborenen Elementen, die in phasenspezifischen Interaktionen mit den Gruppenmitgliedern durch Lernprozesse geformt werden. Protrahierte und progressive Entwöhnung, Partnerspiele, Abweisung und Unterdrückung sind die wesentlichen Vorgänge, die den sozialen Reifungsprozeß bestimmen.Die Gesetzmäßigkeiten der Entwicklung werden am Säuglings- und Mutterverhalten, an den Formen der Selbstbehauptung und der Unterordnung sowie an der Differenzierung der beiden Sexualrollen aufgezeigt und mit biologischen Reifungskriterien, wie Gewicht, Zahnen, motorische Entwicklung und Spermatogenese, korreliert.

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Summary The behavioral ontogeny of ten infant squirrel monkeys (Saimiri sciureus) raised in mixed groups was studied during more than 1200 hours of protracted observation, comprising a life span from birth to the third and parts of the fourth year. The complete development is divided into seven phases and emphasis is placed on infant-group rather than on mother-infant relationships.For the first month of life the most prominent type of interaction between mother and infant is tactile. Acoustic, tactile and visual interaction with group mates starts as early as the first day of life. From about two weeks on a strong social bond is established between the infant and a female group mate, the so-called aunt. Aunt-infant interactions show greater variation than mother-infant interactions.As the infant gains motor independence during its second month, motherinfant visual interaction increases and weaning starts. The infant begins to play with other juveniles. Most of the species-specific behavioral elements are already present.During the 5th and 9th months the mother-infant detachment progresses gradually. During these two periods new behavior patterns develop and others change in frequency and in context of occurrence.At the beginning of the second year, during final weaning, the juvenile male establishes a closer relationship to the alpha-animal. Play fighting and progressive suppression during the second and third year lead to severe fighting. The young male becomes sexually mature at 33 months.The behavior, based on innate elements, is developed further through learning during stage-specific interaction with group mates. Prolonged and progressive weaning, social play and various forms of rejective and suppressive behavior strongly influence the maturation of social behavior.The rules which govern behavioral development are exemplified by the mothernewborn behavior, dominant-submissive behavior, and the sexual role differentiation. The various periods are correlated with physical developmental criteria such as weight, toothing, motor development, and spermatogenesis.

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Herrn Professor Dr. Dr. h. c. Heinrich Klüver, Sewell L. Avery Distinguished Service Professor of Biological Psychology, University of Chicago, zum 70. Geburtstag gewidmet.

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Für die unermüdliche Hilfe beim Beobachten, Protokollieren und Auswerten der Resultate danken wir unseren technischen Assistentinnen Roswitha Koschnick, Helga Krohn, Ilse Kutschera und Sigrid Schürmann, für die aufopfernde Pflege der Tiere Herrn Erasmus Soiderer.