There have been suggested the following scales of communication by Wilbur Schram; as A) Time Consuming Channels: These channels are studied vis-a-vis time consumption, as we fully devote our attention to receive the message either listening to a speech on air, or a engaged in face-to-face meeting. It is closely related to time factor and is solely dependent on our listening, understanding and absorbing the message and does not apply to our visual capabilities. It is closely associated to a certain span of timing.

B) Space Covering Channels: In contrast to the above -said time -consuming channels, the visuals cover the space, on which the message has been put into writing or painted or drawn forms which make a heavy demand on your eyes. We can get the message of an article, magazine or a book, only if we examine closely and carefully the pages of the relevant written or painted matter. All these things or articles of messages which require our visual powers to cover the spaces are called visuals. Thus visual messages can be understood only, if we scan through the pages.

C) Combination of time  — Consuming and space – Covering channels: These channels call for both listening and visual powers to get at the messages at the same time. For example the film in a cinema – house, or viewing television programme; the viewers are required to utilize their visual as well as listening powers simultaneously to get to the message properly. In other words, it is the combination of two human senses working together and at the same time.

With reference to the said several channels of communication, noted psychologists have deduced interesting results by making a comparative study of channels, effectiveness, pervasiveness and permeability as far as human learning and retention is concerned. A man learns eleven percent through hearing and eighty three percent through sight; whereas twenty percent is retained of what is heard, and fifty percent is retained of what is heard and seen effectively.

As such those channels which comprise of both hearing and viewing powers at the same time, are essentially durable and effective and long lasting. In this line of arguments, the face – to – face communication whether in a public meeting, personal meetings between pals, class prrm, relatives or business meeting and religious congregations are more effective and are of far reaching effects. In the present day forms of communications, television is considered more effective and pervasive form as compared with radio or newspaper.