10.7 The Cooperative Principle

We have been looking at how to craft prompts so that they sound natural in context. In this section, we turn our attention to the natural interpretations that listeners make when they hear messages in context.

Conversation is more than just people exchanging information. When we participate in a conversation, we follow the Cooperative Principle: We "get along" by sharing assumptions and expectations regarding the topic, how the conversation should develop, the quality and quantity of the contribution that each participant is expected to make, politeness, consistency, and so on. Conversation's naturally cooperative undercurrent enables us to interpret each other's utterances. Consider the examples in (78) and (79).

(78)

A:

I saw Mark having dinner with a woman last night.

(79)

A:	What a day! I need a drink.
B:	Have you ever been to the Eagle?

Assuming that we all know that Mark is a married man, the sentence in (78) means that Mark was dining with a woman who was not his wife, even though his wife is of course a woman. Presumably, if Mark had been dining with his wife, the speaker would have said so, in the interest of being cooperative. In (79), if speaker A acts on the assumption that B's reply is relevant, A will assume that B's question is intended to function as a recommendation to go to a place called the Eagle. Again, in the spirit of cooperation, A can further interpret that the Eagle is nearby, is open, and is a place that serves drinks. Imagine if one of these conditions were not true. If, for instance, the Eagle were hundreds of miles away, B's conversational behavior would indeed be inappropriate.

Because the meanings of messages in conversations are not tied to their literal, superficial meanings, prompt writers must take care with the interpretations that listeners will infer in context. In example (80), the welcome message permits an inference that is later contradicted by the main menu prompt.

(80)

WELCOME PROMPT:	Hello, and welcome to the Frequent Buyer Rewards Line. You can now redeem points online, at www dot frequentbuyer dot com, forward slash, Points.
MAIN MENU PROMPT:	How can I help you? <pause> You can say, "Buy points," "Redeem points," "Transfer points," ...

The wording of the welcome message allows callers to infer that they must go online to redeem points. In other words, it seems as though this feature is not supported by the speech interface; otherwise, why would the VUI's persona be providing the Web address? Despite this legitimate interpretation, "redeem points" turns up among the main menu options in the very next prompt.

A corollary of the Cooperative Principle requires that speakers be informative. Conversation analysts refer to this principle as the Maxim of Quantity (Grice 1975), which holds that a speaker's contribution to a conversation is as informative as is required to advance the perceived purpose of the conversation. This principle is sometimes violated in speech applications. Example (81) is from a voice mail system. The context is as follows: The subscriber has just logged in with a passcode and is receiving his or her new message count.

(81)

The following [two, three, four . . .] new messages have not been heard.

Assuming that the system's contribution is informative, the caller has no choice but to infer that sometimes new messages can already have been heard. The message strikes a chord of dissonance because, for most people, a "new message" is one that has not yet been heard. After using this voice mail system for a while, you may (or, sadly, may not) realize that a "new message" is intended to refer either to a message that you have never heard or to a message that you have heard, even if in part, but have not yet saved or deleted (e.g., when you skip a message). A more straightforward version of the message would be simply, "You have [two, three, four . . .] new messages." Giving common words new and counterintuitive definitions can impede comprehension and adversely affect the usability of a VUI.

From these examples involving the Cooperative Principle and corollaries such as the Maxim of Quantity, we see that conversations are more than literal messages designed to exchange information. For Richards (1980), conversation "consists of exchanges which are initiated and interpreted according to intuitively understood and socially acquired rules and norms of conversational cooperation, which can in turn be manipulated to create a wide range of meanings beyond the level expressed directly by the utterances in the conversation themselves." This chapter argues that interactions with speech applications must not be treated as exceptions in this regard.