Download An ERP study on agreement violations in Arabic: Qualitative

An ERP study on agreement violations in Arabic:
Qualitative differences between singular and plural subjects
R. Muralikrishnana & Ali Idrissib
a New York University Abu Dhabi, b United Arab Emirates University
[email protected]
Introduction
Methods
Verbs in Arabic generally agree with the subject in person, number
and gender. However, for plural subjects, the verb agrees fully in
the subject-verb (SV) order, but it only agrees in person and gender
in the VS order. Thus, a partial agreement for plural subjects does
not always entail ungrammaticality, whilst it does for singular
subjects. In this ERP study, we investigated whether the processing
system is sensitive to this idiosyncratic behaviour of plural subjects
(in the VS order) even when processing verb agreement in the SV
order. If that is so, qualitatively different ERP patterns must emerge
at the verb for sentences with singular as opposed plural subjects.
Previous studies on subject-verb agreement violations in various
languages have reported a LAN in 40–74 % of cases depending upon
the feature (person, number or gender) that was violated [1]. Given
the paucity of ERP studies on Arabic, we used equal number of
stimuli that violated one of these features, and averaged the effects
for the three features to gain a first insight into the overall general
effect of violating subject-verb agreement in this language.
Results
ERPs at the position of the verb : Singular versus Plural subject
Acceptable
Agreement
Participants:
§ 28 (9 female) right-handed native speakers of Arabic
§ Mean age: 22.14 years; Age-range: 19 – 27 years
EEG Data:
§ Recorded using ActiCap fixed at the scalp; 25 Ag / AgCl electrodes
§ Reference: Left-mastoid, re-referenced to linked mastoids offline
§ Ground electrode: AFZ; Offline filter: 0.3 – 20 Hz band-pass
Procedure:
§ Rapid serial visual presentation of stimulus sentence
§ Tasks: Acceptability judgement followed by Probe detection
Materials:
§ Sentences of the form: Adverb of time – Subject – Verb – PP.
§ Subject noun : masculine / feminine animate common noun
§ 3 Conditions (120 sentences in each condition per participant)
• Acceptable / Violation of Agreement / Violation of Tense
• No combined violation of two agreement features
§ 2 Subject-Types
• Singular noun in sentences with a past tense adverb
• Plural noun in sentence with a future tense adverb
Tense
Discussion
Topography of effects for Agreement Violations
VAG_S – ACP_S _
` VAG_P – ACP_P
Results
§ All violation conditions elicited a biphasic N400-P600 pattern.
§ Acceptable sentences with singular subjects elicited a P300 effect.
§ Agreement violations elicited a LAN when the subject was singular.
§ No difference between past-to-future and future-to-past violations.
[1] Molinaro, N., Barber, H.A., & Carreiras, M. (2011). Cortex, 47(8), 908–930.
[2] Osterhout, K., Mobley, L. (1995). Journal of Memory and Language, 34, 739-773.
[3] Barber, H., & Carreiras, M. (2005). Journal of Cognitive Neuroscience, 17(1), 137–153.
[4] Roehm, D., Bornkessel, I., Haider, H. & Schlesewsky, M. (2005). NeuroReport, 16(8), 875-878.
[5] Roehm, D., Bornkessel-Schlesewsky, I., Rösler, F. & Schlesewsky, M. (2007). Journal of Cognitive Neuroscience, 19(8), 1259–1274.
[6] Kretzschmar, F. (2010). Unpublished doctoral dissertation, University of Marburg, Germany.
Whilst subject-verb agreement violations elicit a LAN effect in several
languages [e.g., 2,3,4], a recent review has suggested that ‘a more
robust expectation for a supposed-to-agree constituent in fact triggers
a more reliable LAN effect’ [1, p. 919]. In light of this, the LAN elicited
by singular subjects as opposed to plural subjects in our data could be
interpreted as follows: there is only one possible agreement pattern for
Arabic singular subjects, giving rise to a specific expectation as far as
agreement is concerned; any deviation from this pattern would be a
clear morphosyntactic violation, eliciting a LAN. By contrast, since
Arabic verbs agree differentially to plural subjects based on argument
order, a partial agreement may not always be a violation, so no LAN.
Further evidence for such an expectation based interpretation stems
from the P3b effect for singular subjects in acceptable sentences in our
data. The P3b has been observed for linguistic stimuli whenever a prior
expectation about the stimulus is fully met [5,6]. In line with this, it
follows that when the expectation for a specific agreement pattern is
fully met (as in the acceptable singular condition), a P3b is evoked.
Such an expectation would be relatively less specific for plural
subjects given their idiosyncratic behaviour, thus no P3b for acceptable
sentences with plural subjects. We argue that our results show the
differential nature of processing verb agreement for singular and
plural subjects due to properties specific to Arabic.
Poster Presented at the 26th CUNY Conference on Sentence Processing, University of South Carolina, Columbia, SC.
Muralikrishnan & Idrissi (2013).