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ERP indices of referential informativity in visual contexts

Authors:
Elli Tourtouri at Osnabrück University
Elli Tourtouri
Francesca Delogu at Saarland University
Francesca Delogu
Matthew W Crocker at Saarland University
Matthew W Crocker
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Abstract

Violations of the Maxims of Quantity occur when utterances provide more (over- specified) or less (under-specified) information than strictly required for referent identification. While behavioural data suggest that under-specified (US) expressions lead to comprehension difficulty and communicative failure, there is no consensus as to whether over- specified (OS) expressions are also detrimental to comprehension. In this study we shed light on this debate, providing neurophysiological evidence supporting the view that extra information facilitates comprehension. We further present novel evidence that referential failure due to underspecification is qualitatively different from explicit cases of referential failure, when no matching referential candidate is available in the context.
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ERP indices of referential informativity in visual contexts
Elli Tourtouri, Francesca Delogu & Matthew Crocker
Saarland University
Introduction
Over-specification: more information than required for referent identification
Ubiquitous in language use [1]
Detrimental [2] or beneficial [3] to comprehension?
Under-specification: less information than required for referent identification
Leads to comprehension difficulty [4] and communicative failure
As detrimental to comprehension as explicit referential failure (mismatch)?
ERP study testing the effects of over- & under-specification on visually-situated
language processing
Hypotheses: (1) over-specification facilitates (or does not hinder) comprehen-
sion – speakers would unlikely over-specifiy, if it did. (2) under-specification
hinders comprehension, but possibly not in the same way as explicit referen-
tial failure.
(a) Minimally-specified (MS) (b) Over-specified (OS)
(c) Under-specified (US) (d) Mismatch (MM)
Figure 1: Sample item. The instruction "Find the yellow bowl" is paired with each of
the four displays (conditions).
Materials
Factor manipulated: Informativity
Conditions: minimally-specified (MS), over-specified (OS), under-specified
(US), mismatch (MM)
Item = spoken instruction (in German) + 4 displays (Fig.1)
Distinguishing features: colour or pattern
Only same-gender objects in the display
Counterbalanced target type, position, colour & pattern
Filler descriptions: 0 or 2 modifiers, always MS
Latin square design
Method
32 items per condition, 128 fillers
33 native German speakers
Trial: preview (3s) →fixation cross (500ms) →instruction →wrap-up screen
(500ms) →task
Task: indicate which side of the screen the target object appeared on (OS, MS)
or whether such a decision was not possible (US, MM)
EEG recorded from 26 Ag/AgCl active electrodes (10-20) system with BrainAmp
amplifier (Brain Products)
Analyses performed on -200–1000ms averaged epochs time-locked to adjec-
tive and noun onsets
Planned pairwise comparisons between conditions (OS, US, MM vs. MS)
Predictions: we expected (1) OS to modulate an N400-like component – OS be-
ing less negative than MS, (2) US to yield a component related to processing dif-
ficulty – possibly qualitatively different from MM
Results
Adjective
No significant differences for OS & MM vs. MS
US vs. MS: broad positivity starting around 400ms, more pronounced on right
electrodes
Noun
Graded N400-like effect: OS < MS < MM
US vs. MS: positivity sustained from adjective region through 800ms post-
noun
Figure 2: ERP waveforms time-locked to the onset of the adjective.
Discussion
The graded N400-like effect reflects the visually-determined predictability of
the noun
OS →reduced N400
Over-specification is beneficial to language comprehension
Referential failure due to US is qualitatively different from explicit referential
failure (MM)
The adjective is redundant but also unhelpful (it identifies two objects of the
same type)
Update of mental model of what is being said [5]: (1) general expectancy for
disambiguating information to come in before the noun, or (2) formulation of
specific predictions as to what the next adjective should be, given information
so far
References
[1] Deutsch W. & T. Pechmann (1982). Social interaction and the development of definite descrip-
tions. Cognition, 11, 159-184.
[2] Engelhardt, P. E., S. B. Demiral, & F. Ferrreira (2011). Over-specified referring expressions impair
comprehension: An ERP study. Brain and Cognition, 77, 304-314.
[3] Arts, A., A. Maes, L. Noordman, & C. Jansen (2011). Overspecification facilitates object identi-
fication. Journal of Pragmatics, 43, 361-374.
[4] Engelhardt, P. E., K. G. D. Bailey, & F. Ferrreira (2006). Do speakers and listeners observe the
Gricean Maxim of Quantity. Journal of Memory and Language, 54, 554-573.
[5] Hoeks, J. C. J., L. A. Stowe, P. Hendriks, & H. Brouwer (2013). Questions Left Unan-
swered: How the Brain Responds to Missing Information. PLoS ONE, 8(10), e73594.
doi:10.1371/journal.pone.0073594.
March 19-21, 2015 28th CUNY Conference on Human Sentence Processing | University of Southern California E-mail: elli@coli.uni-saarland.de
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Questions Left Unanswered: How the Brain Responds to Missing Information
Article
Full-text available
It sometimes happens that when someone asks a question, the addressee does not give an adequate answer, for instance by leaving out part of the required information. The person who posed the question may wonder why the information was omitted, and engage in extensive processing to find out what the partial answer actually means. The present study looks at the neural correlates of the pragmatic processes invoked by partial answers to questions. Two experiments are presented in which participants read mini-dialogues while their Event-Related brain Potentials (ERPs) are being measured. In both experiments, violating the dependency between questions and answers was found to lead to an increase in the amplitude of the P600 component. We interpret these P600-effects as reflecting the increased effort in creating a coherent representation of what is communicated. This effortful processing might include the computation of what the dialogue participant meant to communicate by withholding information. Our study is one of few investigating language processing in conversation, be it that our participants were 'eavesdroppers' instead of real interactants. Our results contribute to the as of yet small range of pragmatic phenomena that modulate the processes underlying the P600 component, and suggest that people immediately attempt to regain cohesion if a question-answer dependency is violated in an ongoing conversation.
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Overspecification facilitates object identification
Article
  • Jan 2011
  • J PRAGMATICS
Referential expressions often contain more information than what is strictly necessary for unique identification of the entity the expression refers to. If this extra information slows down the identification process, then this would suggest a violation of one of the Gricean maxims in the category quantity. A perception experiment was conducted in which overspecification was defined exophorically as the elements of referential expressions that denote non-uniquely identifying information of entities in a particular task environment. In the experiment, identifying information either related to object characteristics (size, color, shape) or location (on vertical or horizontal axis). The results of the experiment provide information about the effect of overspecification on the identification time. Overspecified expressions lead to faster identification when they allowed the reader (i) to fully complete a mental image of the entity and (ii) to delimit search behavior to a specific part of the task context. Extra information about vertical location (top, bottom) proved more efficient than extra information about horizontal location (left, right).
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Do speakers and listeners observe the Gricean Maxim of Quantity?
Article
  • May 2006
The Gricean Maxim of Quantity is believed to govern linguistic performance. Speakers are assumed to provide as much information as required for referent identification and no more, and listeners are believed to expect unambiguous but concise descriptions. In three experiments we examined the extent to which naïve participants are sensitive to the Maxim of Quantity. The first was a production experiment which demonstrated that speakers over-describe almost one-third of the time. The second experiment showed that listeners do not judge over-descriptions to be any worse than concise expressions. The third experiment used the Visual World Paradigm to assess listeners’ moment-by-moment interpretations of over-described utterances. This last experiment revealed that over-descriptions trigger eye movements that can be interpreted as indicating confusion. The results provide support for the use of a simple heuristic such as Minimal Attachment or Argument Saturation to create an initial parse. We conclude that people are only moderately Gricean.
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Social interaction and the development of definite descriptions
Article
  • Apr 1982
  • COGNITION
The present study examines whether a deficit in the production of definite descriptions can be compensated for and successfully resolved in social interaction. We first discuss the developmental reasons for contextually inadequate descriptions and also the mechanisms by which social interaction can reduce processing demands. Then we report on a cross-sectional study using 50 Dutch subjects aged 3, 6, and 9, compared to adults, in which we analyzed the interaction between speaker and addressee in a referential communication task. Our results reveal that all the referential ambiguities in the 6 and 9 year olds, and in the adults, were successfully resolved when the addressee repeated the preceding description in question format, where the initial description (plus the succeeding specification) had not been explicit enough to identify the target referent. In the youngest age group, the 3 year olds, the analogous percentage of resolutions was 89%. Moreover, we found that the length of interaction required depends on age-related differences in the explicitness of the initial descriptions and the (induced) repairs. The main results raise several questions that are discussed under three headings: the role of feedback in speaker-addressee interaction, the possibility of a procedural explanation for production deficits and their compensation, and the possible learning mechanisms underlying developmental changes in referential descriptions.
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