Readability and Usefulness

A great deal of the research into legibility has been done in the printing world. [NaFo] The functions of colour, typeface, font size and so on are reasonably well understood, although there are some ergonomic differences associated between screens and the printed page. On readability, the basic rules of thumb for the following parameters have been established: [LiCo88] There is some understanding of how complexity and style of grammar affects comprehension. However, we have found that there is little work so far on the structure of real time conversations. Nor is there a great deal of work where there are more than two participants. As our starting point we considered a classification of <#1198#> speech acts<#1198#> from Searle so that we could start to identify multi party protocols: He classifies speech into 5 illocutionary acts. These are: We can use these acts to help structure the exchanges in a conference. A directive for example should always require an answer, agreement or acknowledgment and the conferencing system will make provisions so that the person to whom the directive is made will be forced to make a reply before they can continue with the conference. An assertive will normally beg a question (directive), an argument (an assertive not logically consistent with the last made assertive) or evidence or opinion backing up the previous statement (an assertive or expressive). Breaking down communications into these categories enables us to semi-structure (pre-compile into the conferencing system) conversations in advance, enabling the users to be guided and understood more efficiently in their communications. [CaDi89] Even more importantly though placing statements under particular speech act headings will remove a significant amount of ambiguities as well as enabling the hearer a quicker route to understanding the speakers intentions. The proposition ``Close the door'' for example could be a promise or threat, but equally could be a request or order. Placing all propositions under their speech act heading will enable the hearer to remove many of the ambiguities that arise through the loss of information which happens when a speaker's tone and expression are unavailable. Not only can we use these acts to give more structure to the exchanges of text between users, but also for giving weight to their <#1201#> bids<#1201#> for the floor. This has been used by other workers in the area, although only for off-line systems rather than real time ones. Mechanical protocols generally come from a very limited range of the set possible. E.g. ARP ``who-has'', or RPC ``request-response'' or the TELNET IACs, ``do, don't, will, won't''. We believe that the use of speech acts allows a much wider expression for exchanges without losing structure altogether. [ARP82][RPC81][Tel83] The Coordinator is a system which, by exchanging messages restricted to some types chosen to express some of the same ideas as speech acts, (though not in real time) allows better time management of actions. [Wino88]