Eye Movements and Spoken Language
Comprehension: effects of visual context on
syntactic ambiguity resolution
Spivey et al. (2002)
Psych 526
Eun-Kyung Lee
Research Question

Does referential context affect initial parsing of
syntactically ambiguous sentences?
 When referential context supports less preferred
syntactic structure, could it eliminate processing
difficulty in early phrases?
 The role of nonlinguistic factors in sentence
processing
 Garden path model vs. Constraint-based model
Previous Research[1]
Limitations
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Reading time measures restricted to measuring
processing difficulty
 No information about what is being processed how
Misleading notion of referential context
 Not just equated with the preceding linguistic
context
 Salient information in the environment, the set of
presuppositions shared by discourse participants
Previous Research[2]
Two Paradigms

Language-as-action
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Interactive settings
Real-world referents
Clear behavioral goals
Offline methods
Language-as-product
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Online measures
(Response measures time-locked to the linguistic input)
Decontextualized input
Not goal-directed
Current Study

Combines the two paradigms
 Communication task, well-defined context, clear
behavioral goal (Language-as-action)
 On-line measure of eye-movement (Language-asproduct)
Target Sentence

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A temporarily ambiguous prepositional phrase
Put the apple on the towel in the box
Ambiguous region
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Disambiguating region
Preference for a goal argument over an optional
adjunct
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Syntactically simpler (Frazier 1987)
General preference for arguments over adjuncts (Abney
1989)
Linguistic presupposition of uniqueness associated with a
definite noun phrase (Crain & Steedman 1985)
Linguistic Presupposition
& Referential Context

When there is a single entity in the context
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When there is more than one entity in the context
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
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Modification is redundant  favor argument analysis
Referential indeterminacy is created
Modification is required to establish a unique referent
Multiple-referent contexts eliminate processing
difficulty for the otherwise less-preferred modification
analysis (Crain & Steedman 1985, Altmann &
Steedman 1988)
What if there is no referential indeterminacy in
multiple-referent contexts?
Experiment 1
Method
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6 participants
Listen to a spoken instruction read out from a script
Move objects in a visual workspace following the
instruction
Lightweight headband-mounted eyetracker to monitor the
participant’s attentional shifts
3 types of context (one-referent, two-referent, three-andone referent context) with ambiguous and unambiguous
instructions
 Put the apple on the towel in the box
 Put the box that’s on the towel in the box
18 experimental, 90 filler instructions in 36 trials (or
instruction triplets)
Example of an instruction set
Look at the cross
Put the apple on the towel in the box
Now put the pencil on the other towel
Now put it in the box

Critical instructions were always the first instruction in
the set
3 types of Visual Context [1]
One-referent context
 Single referent
 If there is a garden path
effect, more looks to the
empty towel for “on the
towel” in the ambiguous
instruction compared to
the unambiguous
instruction
3 types of Visual Context[2]
Two-referent context

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Multiple referents (eliciting
referential indeterminacy)
whether referential
context eliminates garden
path effect
If a referential account is
correct, looks to the
incorrect goal should be
eliminated in the
ambiguous instruction
 modifier interpretation
3 types of Visual Context[3]
Three-and-one-referent context

Multiple referents (eliciting
no referential indeterminacy)
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Whether linguistic
presuppositions with definite
NPs are used on-line in
resolving syntactic ambiguity

If yes, looks to the incorrect
goal should be eliminated in
the ambiguous instruction 
modifier interpretation
Results[1]
Distractor Object
Incorrect Goal
Results[2]
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One-referent context
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Two-referent context
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More frequent saccade (55%) out of the target referent region and
into the incorrect goal region in the ambiguous instruction
Rare looks at the incorrect goal (14%) in the ambiguous instruction
No difference between the ambiguous and unambiguous
instructions
Three-and-one referent context
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No significant difference in looks at the incorrect goal between the
ambiguous (0%) and unambiguous instructions (22%)
The decision to modify the noun phrase is not purely due to
the presence or absence of referential indeterminacy
Reflects on-line access to specific presuppositions associated
with definiteness and modification
Results[3]
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Referential contexts influence an initial interpretation
of ambiguous sentences
However,
Possible confounding effects by some intonational
patterns
Experiment 2
Method
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The same stimuli and instructions as Experiment 1,
but with prerecorded instructions
6 participants
Ambiguous instructions were digitally converted from
the unambiguous versions by editing out “that’s”
e.g. Put the apple that’s on the towel in the box
 What about the prosodic cues in the critical
regions?
Results[1]

Parallel results with those of experiment 1
Results[2]
Combined Analysis of Exp 1,2
One-Referent
Incorrect Goal
> Correct Goal
Garden Path Effect
in the ambi. condition
Results[3]
Combined analysis of Exp 1,2
Two-Referent
fixation to the distractor
referent due to
Referential indeterminacy
No difference b/w
ambi. and unambi.
conditions
Results[4]
Combined analysis of Exp 1,2
Three & One
Referent
Fewer fixation to
distractor reference
No difference b/w
ambi. and unambi.
conditions
Only a few fixation to
Incorrect Instrument
Summary
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Referential contexts play an initial role in parsing
(even when the verb takes an obligatory verb
argument)
The online use of linguistically coded presuppositions
even in the absence of referential indeterminacy
(Three & one reference context)
Supports a constraint-based model of parsing
Thank you!