The 31st Language Lunch
Date: 2012-02-10
Location: G.07 Informatics Forum
Using Latent Variable Models to Achieve Stochastic and Consistent User Simulation for Dialog Management
Aciel,Eshky; informatics; a.eshky@sms.ed.ac.uk
Ben,Allison; informatics; b.allison@inf.ed.ac.uk
Mark,Steedman; informatics; steedman@inf.ed.ac.uk
User simulation is a vital component in training and evaluating statistical dialog systems. However, while the dialog managers they inform have become ever more sophisticated, user simulators have not generated the same level of research or experienced the same advancements: typical simulators require some hand-crafting, they are difficult to evaluate without the managers they are intended to train (leading to circularity of argument) and their influence on the resulting policies of dialog managers remains unexplored. In this paper, we propose a fully generative user simulator that is fully induced (without hand-crafting or goal annotation). The simulator is both stochastic (its behaviour is probabilistic) and consistent (user utterances are generated conditional on a goal, which remains fixed for the dialog). Goals are represented in the model as latent variables, and it incorporates a topic model which clusters together utterances with similar semantics or confusable phonetics, but different surface renderings. Because it is a fully fledged generative model, we are able to evaluate in terms of held-out probability, breaking the circularity common in many previous evaluations of user simulators. Our results demonstrate substantial improvement over a simple fully-generative bigram model, as well as an upper bound on models treating goals as string literals.
Beyond Dysarthria: Phonological and Orthographic Deficits in Motor Neurone Disease
Phillipa,Rewaj; PPLS; s0880973@sms.ed.ac.uk
Sharon,Abrahams; PPLS; s.abrahams@ed.ac.uk
Bob,Ladd; PPLS; bob.ladd@ed.ac.uk
Thomas,Bak; PPLS; thomas.bak@ed.ac.uk
BACKGROUNDrnSingle cases of aphasia associated with Motor Neuron Disease (MND) have been documented since late 19th Century, but until recently received only little attention, most of it focused on semantics and syntax. In contrast, the disturbances in articulation and phonology have been commonly attributed solely to dysarthria. However, recent evidence of spelling errors (Ichikawa et al. 2010) and apraxia of speech (Duffy et al 2007) suggests that some errors cannot be explained by motor impairment alone, raising the possibility of more central processing deficits. rnrnMETHODSrnWe examined 20 MND patients with changes in speech and/or language, using a comprehensive assessment of spelling and repetition as well as syntactic, phonological and orthographical awareness. Patients were screened for levels of hearing impairment, dysarthria, ideomotor apraxia and non-verbal cognitive deficits.rnrnRESULTSrnOut of 20 patients with varying severity of dysarthria, 13 showed deficits not confined to dysarthria. Spelling errors suggest impairment at the level of the graphemic buffer, with word length effects and evidence of omission, substitution, transposition and insertion errors in both elicited and spontaneous writing. Moreover, while 6 patients demonstrated impairment in both receptive and expressive modalities, 2 demonstrated dissociation between impaired comprehension of syntax and orthography, and preserved naming and spelling. We conclude that MND is associated with multiple deficits in spoken and written language and discuss our findings in the context of subvocal rehearsal and an interaction between language and motor functions.
What is a police apology?
Ruth,Friskney; PPLS; R.E.Friskney@sms.ed.ac.uk
Questions about whether the police acted politely can have a bearing on whether specific police powers are deemed to have been used legitimately (Nadler and Trout, forthcoming); whether or not the police are perceived as treating people with politeness and respect is a core component in overall public confidence in the police (Bradford and Jackson, 2009). However, the question of what actually constitutes politeness in a police context has been rarely discussed.rnrnThe position of the police institution is more complex than it may at first appear – although generally perceived as a powerful institution authorised by the state to use force, it may also be positioned as an institution providing public service. The challenges for the police in negotiating these positions of authority and service in relation to politeness can be seen in police constructions of apologies.rnrnThis poster looks at data from the Scottish police, in the form of responses to complaints from members of the public, focusing on how apologies are constructed. My analysis suggests two different types of apologies – one close to a traditional act of an apology ‘for’ an offence, and a second type, seeking to negotiate around public expectations of service from the police institution. The construction of this second act may be part of the Scottish police trying to develop a type of apology act that responds to both their own and public perception of what their police service should be. rnReferences:rnBradford, Ben and Jonathan Jackson (2009) “Public Trust in Criminal Justice: A Review of the Research Literature in the United States.”rnrnNadler, Janice and J. D. Trout. (forthcoming). “The Language of Consent in Police Encounters.” In Oxford Handbook on Linguistics and Law, eds. L. Solan and P. Tiersma: Oxford University Press.rnrn
The Role of Other’s Representations in Verbal Production
Chiara,Gambi; PPLS; c.gambi@sms.ed.ac.uk
Martin,Pickering; PPLS; martin.pickering@ed.ac.uk
Joris,Van de Cavey; PPLS; joris.vandecavey@ugent.be
In natural conversations, people sometimes complete each other’s utterances. How do they manage to do so? One possibility is that they make predictions about their partner’s utterances, just as they can make predictions about their own utterances (Pickering & Garrod, 2009; Gambi & Pickering, 2011). We tested whether participants predict the complexity of their partners’ utterances in a joint picture description task.rnIn a pretest, we asked participants to describe pictures with either a short (e.g.,”the soldier follows the swimmer”) or a long (e.g.,”the soldier follows the swimmer with the vase and the cane”) sentence. Participants took longer to produce the beginning of the sentence (i.e., “the soldier follows”) when it was followed by a long ending compared to a short ending (mean difference=0.218 ms, pMCMC<0.001). We interpret this as evidence that people build predictions concerning what they are going to say next. We expect that similar predictions are built for the upcoming utterances of other speakers.rnWe tested three conditions. After a participant produced the beginning of the description (e.g., “the soldier follows”), either the same participant (SELF), her partner (OTHER), or nobody (NO) had to complete the description with a long or short ending. We expected to find complexity effects in the SELF and the OTHER condition, whereas we did not expect to find any effects in the NO condition (where there is no upcoming utterance). rnThe duration of the sentence beginning was longer before long than before short endings in SELF (p < 0.001) and OTHER (p=0.03), but not in the NO condition. However, we did not find a significant length x condition interaction between OTHER and NO. Therefore, we cannot definitely conclude that the effect in OTHER is due to representing the other’s utterance.
The emergence of procedural conventions in dialogue
Gregory,Mills; Informatics; gmills@staffmail.ed.ac.uk
A key problem for models of dialogue is to explain how conventions are established and sustained. Existing accounts emphasize the importance of interaction, demonstrating how collaborative feedback leads to representations that are more concise (Krauss and Weinheimer 1967; Clark 1996), abstract (Schwartz 1995), systematized (Healey 1997; Mills and Healey 2006), stable and arbitrary (Garrod et al 2007).rnDespite these studies’ very different approaches, a common methodological choice is their study of how interlocutors co-ordinate on the content of referring expressions. However, co-ordination in dialogue also requires procedural co-ordination (Schegloff 2007). To investigate procedural co-ordination we report a collaborative task which presents participants with the recurrent co-ordination problem of ordering their actions and utterances into a single coherent sequence: Pairs of participants communicate via a text-based chat-tool (Healey and Mills 2006). Each participant’s computer also displays a task window containing a list of randomly generated words. Solving the task requires participants to combine their lists of words into a single alphabetically ordered list. To select a word, participants type the word preceded with “/”. To ensure collaboration, participants can only select words displayed on the other participant’s screen and vice versa. Note that this task is trivial for an individual participant. However, for pairs of participants, this task presents the coordination problem of interleaving their selections correctly: participants cannot select each other’s words, words can’t be selected twice, and the words need to be selected in the correct order. (See Mills 2011 for more detailed description).rnDespite the task only permitting a single logical solution (and being referentially transparent – the words are the referents), participants develop group-specific routines for co-ordinating their turns into a coherent sequence. Importantly, we show how this development does not occur through explicit negotiation: in the initial trials, participants’ attempts to explicitly negotiate these routines more often than not prove unsuccessful (cf. Pickering and Garrod 2004, who observed similar patterns in a series of maze game experiments).rnInstead, we demonstrate how these routines emerge via tacit negotiation as a conseqence of interlocutors’ collaborative attempts to deal with miscommunication. Drawing on how interlocutors engage in resolving these misunderstandings in the test phase, we argue that these collaborative routines operate normatively, having become conventionalized by the interlocutors.rnrnReferencesrnClark, H. H. (1996). Using language. Cambridge: Cambridge University Press.rnGarrod, S., Fay, N., Lee, J., Oberlander, J., & MacLeod, T. (2007). Foundations of Representation: Where Might Graphical Symbol Systems Come From? Cognitive Science 31(6), 961-987. rnHealey, P.G.T. (1997). Expertise or expert-ese: The emergence of task-oriented sub-languages. InrnProceedings of the 19th Annual Conference of The Cognitive Science Society. Stanford University, rnHealey, P. G. T. & Mills, G. (2006). Participation, precedence and co-ordination. In Proceedings ofrnCogScirnKrauss, R. M. and Weinheimer, S. (1966). Concurrent feedback, confirmation and the encoding of referents in verbal communication. Journal of Personality and Social Psychology, 4 (3), 343-346. rnMills, G. J. (2011). The emergence of procedural conventions in dialogue. In Proceedings of the 33rdrnAnnual Conference of the Cognitive Science Society. Boston. USArnPickering, M. J. and Garrod, S. (2004). Towards a mechanistic psychology of dialogue. Behavioural andrnBrain Sciences, 27(2), 169-190.rnSchegloff, E. A. (2007). Sequence Organization in Interaction: Vol 1. Cambridge University Press.
