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J A van Hooff

Publications and source records attributed to J A van Hooff.

11 recordsLinked to original sources
PubMed1995

Homologizing primate facial displays: a critical review of methods.

The applicability of previously established criteria for identifying homologous behavioural traits to the ritualized facial displays of primates is discussed and illustrated with several examples. (1) Homologizing of facial displays is based on (a) their stereotypy, (b) their nature as compounds of individual facial actions, and--to a lesser extent--(c) the homology of the muscle substrate by which the displays are accomplished. (2) Sequences of gradually changing displays ('Merkmalsreihen') can be constructed by considering related extant species, different ontogenetic stages, and variation and blends of the underlying motivations. (3) The pattern of distribution of the display in the primate phylogenetic tree reflects the direction of changes ('Lesrichtung'), and thus yields insights into the phylogeny of the displays. (4) The behavioural context of a display reflects its motivational embedding and is inseparable from its function. Therefore the behavioural context does not differentiate between similarities due to common descent and similarities due to identical function.

Animals↗
PubMed1994

An ethological study on behavioural differences between hyperactive, aggressive, combined hyperactive/aggressive and control children.

Frequencies and sequential patterns of behaviour elements in pure hyperactive (N = 12), pure aggressive (N = 13), combined hyperactive/aggressive (N = 15) and control children (N = 10) were recorded in a semistructured playroom session and subsequently compared. The samples were age- and IQ-matched. In an overall MANOVA a significant main effect for hyperactivity but not for aggression was found. The hyperactive children were characterized particularly by differences in squirming and changes in sitting. The sequential patterning of their behaviour revealed weaker temporal contingencies between their behaviour and the conversational speech of the experimenter than in the case of the nonhyperactive (aggressive and control) children. This may be explained by deficits in social attention in the hyperactive groups.

Aggression↗
PubMed1992

The use of adrenocorticotrophic hormone (4-9) analog ORG 2766 in autistic children: effects on the organization of behavior.

In a double-blind placebo-controlled crossover trial, 14 autistic children were treated with the neuropeptide ORG 2766, a synthetic analog of adrenocorticotrophic hormone (ACTH) (4-9). ORG 2766 treatment (20 mg per day during 4 weeks) was associated with an increased amount and an improved quality of the social interaction of the autistic children with a familiar experimenter. These changes in interaction were clinically relevant. Following treatment with ORG 2766 gaze and smile behaviors of child and experimenter showed stronger temporal contingencies. Further, after ORG 2766, stereotypies were temporally disconnected from verbal initiatives. The data supported the notion of a stimulating effect of ORG 2766 on social interaction. The implications of these findings for the endogenous opioid theory of autism are discussed.

Adrenocorticotropic Hormone↗
PubMed1992

Deficits in social behavior in autism and their modification by a synthetic adrenocorticotrophic hormone (4-9) analog.

When charting the structure of the social behavior of autistic children by means of an ethologically analyzed playroom session, deficits appeared in the reciprocity of eye-contact and in the location of verbal initiatives. These deficits in social behavior were beneficially influenced by treatment with the adrenocorticotrophic hormone (4-9) analog ORG 2766.

Adrenocorticotropic Hormone↗
PubMed1991

Differences in the structure of social behaviour of autistic children and non-autistic retarded controls.

Social and task-oriented behaviours of autistic children were compared to those of individually age- and IQ-matched non-autistic retarded controls. Autistic children showed deficits in visual reciprocity, in indicating joint attention and referential head gestures, and in the integration of gaze and gestures when reacting to tasks. The findings confirmed the notion of social and pragmatic communicative deficits in autism. The implications of these findings for theories of social behaviour in autism (avoidance, facial perception, theory of mind) are discussed.

Autistic Disorder↗
PubMed1986

Age-sex class differences in the positional behaviour of the Sumatran orang-utan (Pongo pygmaeus abelii) in the Gunung Leuser National Park, Indonesia.

During a three-year field study of the socio-ecology of Sumatran orang-utans, their use of the canopy was investigated in the Gunung Leuser National Park, Indonesia. This paper concerns the positional behaviour of different age-sex classes of orang-utans. Adolescents and females with infants differed significantly from an adult male in the following respects: the use of locomotion types (more 'quadrumanous scrambling' and perhaps also 'quadrupedal walking' and less 'tree swaying'); substrate use during resting, and travelling and resting heights. We suggest that large body size restricts the travel route options in higher forest strata and necessitates the use of the lower stratum. Here, 'tree swaying' is an efficient method of progression, particularly for heavy animals. Mothers with infants are forced to travel in the lower zones as well. The fact that they return to a greater heights when they go to rest might suggest that they travel lower in spite of a greater predation risk.

Aging↗
PubMed1985

[Pain, perception and expression: an ethological perspective].

To better understand the pain phenomenon, its occurrence and its functional significance, pain should be considered as a part of a behaviour system which activates two functions: defensive and aversive behaviour on the one hand, and recuperative behaviour on the other. In the former especially the more short-lasting primary pain plays a role, in recuperative behaviour more chronic secondary pain is of importance. Pain should not be seen primarily as the unconditioned stimulus in the fear system, but as one of the independent behaviour systems. Within the framework of this ethological model both the facilitative and inhibitive influences which 'pain' and 'fear' exert on each other can be more satisfactorily explained. We assume that animals feel pain on the grounds of the so-called 'analogy decision'. The only objective measure, of course, is the behaviour which is observable as a consequence of harmful influences. This behaviour varies greatly with the nature and localisation of the harmful effects; the variation is dependent on the degree to which behavioural responses can be effective in avoiding damage and promoting recovery, and also on the animal species considered. In some species expressions of pain have been selected for and adapted as social signals which elicit consideration, help and care of conspecifics. In other species social and other factors have precluded stimulation of such a development. All this means that the extent to which spontaneous behavioural expressions can serve as valid pain measures is a complicated question; it leads to consideration of the feasibility of more meaningful experimental measurement methods.

Animals↗
PubMed1980

Types of dominance in a chimpanzee colony.

This study examines to what extent the concept of dominance can be used to describe the social structure of a group of semi-free-living chimpanzees. 15 behavioural variables, based on agonistic, competitive and affinitive behaviour patterns, have been compared with respect to the interindividual directions in which they occurred. In this analysis use was made of indices that reflect the position an individual occupies in the relationship structure. These indices were calculated per individual for all variables and subjected to factor analysis and cluster analysis. As a result, 13 of the variables could be grouped in three categories which have been labelled: (1) agonistic dominance; (2) bluff dominance, and (3) competitive dominance. Whereas the top positions in the hierarchies based on the first two closely related types of dominance were occupied by the adult males, the hierarchy based on the third type was headed by several adult females.

Agonistic Behavior↗
PubMedDate not supplied

Aging, dominance history, and social behavior in Java-monkeys (Macaca fascicularis).

The aim of this study was to investigate the influence of the dominance history of socially housed Java-monkeys on the aging process. In monkeys, social subordinance is generally associated with elevated levels of cortisol, which, in turn, have been suggested to influence cognitive decline. As cognitive skills are necessary for successful social life, we investigated the effect of old age in relation to the dominance history of the animals on their social behavior by comparing old females with their younger daughters. Old age, especially in combination with a history of low rank, led to a withdrawal from social interactions with unfamiliar animals and to a decrease in amounts of aggression received. Still, however, old animals showed an increase in behaviors associated with arousal. A reduced ability to deal with complex social interactions, caused by a decline in information processing abilities, is suggested as an explanation for these results.

Aggression↗