Three videotapes of diagnostic interviews were rated by psychiatrists at several different centres in the British Isles. Audiences were asked to use a number of rating schedules including a list of 116 technical psychiatric terms. They were also asked to make a provisional diagnosis. The influence of the psychiatrists' concepts of normality and the type of training and other factors such as age on the perception and quantitative assessment of psychiatric symptoms and the use of technical terms is discussed. Maudsley-trained raters tended to see fewer symptoms of all kinds in all three patients, while Glasgow psychiatrists made more ratings of affective symptoms–both manic and depressive—on two of the three tapes. Dublin raters use more ‘dynamic’ terms in their daily routine than do raters from the United Kingdom. Raters over 40 years of age tended to use ‘dynamic’ terms more often than raters under 40 years. Raters trained in university departments differed only slightly in the terms they used from those trained in area mental hospitals. This study points to the problems of psychiatric communication within one culture.