Detecting and exploiting user familiarity in natural language human-computer dialogue

1. Human-computer dialogue and usability 1.1 What is human-computer dialogue? The fields of application for human-computer dialogue are both many and various. Users may dialogue with customer services over the phone or via a personal digital assistant in order to carry out banking transactions, find their way around a city, or book train or plane tickets (Wilkie et al., 2005). The modality of interaction between user and system can also be either partially or totally speech-based. System messages or prompts can be delivered to the user via either a screen (text, graphics) or an auditory modality (pre-recorded or computer-generated voice). User data entry is possible through speech or via either a phone or a computer keyboard, and in the case of advanced systems, users can submit their requests in natural language (see Gorin et al., 1997, Le Bigot et al., 2007). Furthermore, current systems propose a wide range of interaction styles. The dialogue can be guided by the system (system-initiated), the user (user-initiated) or both (mixed-initiated) (see Lai et al., 2008, for details). In system-initiated dialogue, which is the most common, the interaction is led by the system and may appear mechanistic. In the following examples, the system either questions the user or offers him or her a choice. For example, the system may say, " To buy the share, press 1, and to sell the share, press 2 ". The user then presses 1 or 2 on his or her phone keypad. For a speech system with explicit keywords, the " Press 1 " or " Press 2 " is replaced by a verb or a common noun: " To buy the share, say Buy, and to sell the share, say Sell ". The user says the keyword aloud and continues the interaction. For a speech-based system with implicit keywords, the choices are suggested. The system may ask the user, " Do you want to buy or sell the share? ". The user must then say the " buy " or " sell " verb aloud to continue the interaction (a system with natural language capability would be able to recognise a response such as, " I want to buy the share "). User-initiated systems are few and far between. However, they offer users greater freedom and flexibility. Once they have asked the user what he or she wants (" What do you want? "), the interaction continues in …