Ethological strategies for defence in animals and humans are expressed as either aggression or flight behaviour. Aggression is employed by animals during intraspecific competition for resources, mate, territory and acquiring and maintaining social status. It also disperses individuals throughout the biotope. Flight behaviour is used to avoid a source of danger or harm, has both dynamic arid static forms, is phylogenetically very old and takes precedence over all other activities including social behaviour. Animals exposed to inescapable threats or attacks exhibit a characteristic defensive strategy, arrested flight, which consists of gaze-avoidance or cut-offs, cryptic postures such as immobility and covert surveillance of their surroundings. Arrested flight also occurs in social encounters when submission fails to reduce attacks, and in prey animals when escape from a predator is hampered. Ethological studies show that during interviews, depressed patients exhibit a pattern of non-verbal behaviour having all the hallmarks of arrested flight. Cut-off behaviour, which seeks to reduce the input of flight-evoking stimuli is especially evident in these patients but takes an extreme form, i.e. eye closure, in the gaze-profiles of paranoid patients. It is proposed that cut-offs always denote the presence of incipient flight and that arrested flight is a 'last measure' defensive strategy in response to inescapable proximal threat. It can arise in humans whenever their escape routes are hampered and characterizes the behaviour of patients suffering from depression. As in animals, different pathways may lead to arrested flight in humans. In humans, defensive mechanisms also operate at the mental level through putative ego defences, the psychological function of which is to preserve self-esteem by hindering the access of disturbing emotional material into awareness. It is suggested that they function ethologically as mental cut-offs analogous to the behavioural cut-offs in animals.

Ethology is concerned with the observation, description and measurement of the acts and postures which make up the behavioural repertoire of animals. Man too, exhibits analogous patterns of non-verbal behaviour, many of which serve social interactions. It is shown how ethological profiles of psychiatric patients can be constructed using the same methods as are used to analyse the social behaviour of rodents. It is argued that deficits in social behaviour are a key feature of the mentally ill patient and arise when flight, i. e. escape-oriented behaviour predominates. This notion is supported by an ethological study which shows that compared to healthy subjects, depressed patients exhibit fewer facial expressions and gestures which instigate or invite social interactions. These patterns serve to isolate the depressive patients from the group. With its emphasis upon objective analysis of behaviour, the ethological approach can provide a useful adjunct to conventional but largely subjective, clinical assessment schemes. It can also help to integrate findings in man and animals since in both, the behaviour is assessed in the same kind of units according to a common conceptual framework.

The aim of this study was to objectively quantify the effects of radiological teaching on student performance in interpreting radiological images, and to establish whether training location affects performance. 114 clinical students were asked to anonymously interpret radiological cases before and after 26 weeks clinical training. Improvements were assessed by comparing performance on the median question in each assessment using the Kruskal-Wallis analysis. Variations according to different placements were assessed by the Mann-Whitney U-test. There was a highly significant (p<0.001) improvement in the performance of the group with training. The proportion of correct answers to the median question improved from 8% to 43%. Differences between training placements were non-significant. Our study suggests that radiology teaching significantly improves student performance. Future work should look to define the contribution of "clinical exposure" towards this improvement, as well as the various teaching methods employed.

We have investigated the reliability of communication of uncertainty in radiological reports. The 18 most commonly used verbal expressions of probability were identified from a series of radiological reports. 11 clinicians (three radiologists, three rheumatologists and five orthopaedic surgeons) recorded the probability that they ascribed to each of the 18 expressions using visual analogue scales. Each subject was re-tested on four occasions at least 1 week apart. The results were analysed to assess reproducibility within and between individuals. We found considerable variation in the probabilities assigned to many commonly used expressions between subjects, and between repeated testing of the same subject. Some expressions were rated much more consistently than others. "Absent", "excludes", "unlikely", "probable", "certain" and "definite" were the most consistently rated expressions. We have identified a potential source of misunderstanding in radiological reports owing to differences in interpretation of expressions used by radiologists and referring clinicians.

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