From the 1975 programme notes:
It is part of everyday social experience that we receive and send out signals indicative of our emotional or mental state. 'He looked happy' ... 'she sounded rather anxious' ... 'he parted with a confident handshake' ... 'there was the smell of fear about' ..., are all phrases which we use without really thinking about the nature of the signals involved. Most of the code, irrespective of the sense through which the message is received, almost certainly has to be learned. If we are faced with an individual whose social training has been entirely in another culture, such as a Japanese who has never been to Europe before, only very elementary signals get through in either direction. Perfume, make-up, and even hair styles may be used as signal flags which reinforce the impression we would like to create, probably by imitating and exaggerating the natural code. So far there is very little about this which we can measure, though there are people like caricaturists and actors who have obviously identified some of the important parts of the code and can produce the signals at will.
On the other hand emotion also affects many of the physiological factors mentioned in the previous lectures. This is a disadvantage to the doctor who may be misled by a temporary, emotion induced, abnormality, but also provides the basis for the work on 'lie detectors'. Some are obvious to the naked eye. a blush or a sudden pallor are no more than a change in the blood supply to the skin for instance.
During this course of lectures you, the audience, will get some impression of the personality and mood of the speaker, try to identify the clues on which you base your conclusions!