methodology experiment 1: - within-subjects 2 (cw/ rw) x 2 (consistent/ inconsistent) design - 40...
TRANSCRIPT
METHODOLOGY
• Experiment 1: - Within-subjects 2 (CW/ RW) x 2 (consistent/ inconsistent) design - 40 experimental items in each condition (total 160) displayed in a fixed random order alongside filler items - 19 native English speakers
• Experiment 2: - Within-subjects 1-factor (NW-consistent/ NW-inconsistent) design - 40 experimental items in each condition (total 80) displayed in a fixed random order alongside filler items - 20 native English speakers
• EEG continuously recorded from 72 scalp electrodes and averaged time- locked to onset of consistent/ inconsistent critical word
EXPERIMENTAL ITEMS
RW- inconsistent / consistentIf cats are hungry they usually pester their owners until they get fed.Families could feed their cat a bowl of carrots/ fish and it would gobble
it down happily.CW- consistent/ inconsistentIf cats were vegetarians they would be cheaper for owners to look after.Families could feed their cat a bowl of carrots/ fish and it would gobble
it down happily.
EXPERIMENTAL ITEMSNW- inconsistent/consistentIf cats were not carnivores, they would be cheaper for owners to look after.Families could feed their cat a bowl of carrots/ fish and it would gobble it
down happily.
REAL-WORLD INTERFERENCE IN DETECTING VIOLATIONS OF COUNTERFACTUAL AND NEGATED WORLDS
Heather J Ferguson, Anthony J Sanford & Hartmut Leuthold Department of Psychology, University of Glasgow ([email protected])
BACKGROUND•The ability to update our current knowledge using contextual information is a vital process during every-day language comprehension.
•Counterfactual and negated reasoning are essential ingredients of our everyday cognition. Counterfactuals involve an understanding of events that are counter to reality, while negated statements cancel real-world expectations, but do not create an alternative model (Fauconnier, 1994).
•To date, surprisingly little is known of how these types of reasoning are processed during reading or listening (Ferguson & Sanford, submitted; Ferguson, Sanford & Scheepers, 2007; deVega et al., in press).
•Increasing evidence suggests that a strong discourse context can overrule local lexical-semantic factors when these two conflict and as such can immediately influence comprehension processes.
•This has been demonstrated by the N400 effect, which is highly sensitive to the ease of integration of the meaning of a word into the prior sentence or discourse (Van Berkum et al., 2003; Niewlands & Van Berkum, 2006).
•The issue we examined, therefore, was whether the introduction of counterfactual or negated discourse contexts can eliminate effects of real-world knowledge in the ERP components.
GLASGOWLANGUAGEPROCESSING
CONCLUSIONS•RW violations within a RW context lead to an N400 effect at the critical word (Experiment 1), which reflects the fact that readers have detected the anomaly.
•Within an appropriate CW context (Experiment 1), the N400 effect is reversed so that local- semantic RW violations are processed as acceptable and RW congruent items as anomalous.
•In Experiment 2, the N400 to RW anomalous rather than congruent continuations demonstrates that the NW context has not ‘neutralised’ the RW anomalies in this way.
•In sum, these experiments suggest that semantic analysis is context-dependent only when an alternative model is immediately available.
De Vega, M., Urrutia, M., & Riffo, B. (in press). Cancelling updating in the comprehension of counterfactuals embedded in narratives. Memory and CognitionFauconnier, G. (1994). Mental Spaces. Cambridge, UK: Cambridge University Press. Ferguson, H.J. & Sanford, A.J. (submitted). Anomalies in Real and Counterfactual Worlds: An eye-movement investigation.Ferguson, H.J., Sanford, A.J. & Scheepers, C. (2007). Predicting events according to a counterfactual world or the beliefs of others: evidence of a gender bias in processing. Poster presented at Brain Mechanisms and Cognitive Processes in the Comprehension of Discourse, Lorentz Centre, Leiden, The Netherlands.Nieuwland, M.S. & Van Berkum, J.J.A. (2006). When peanuts fall in love: n400 evidence for the power of discourse. Journal of Cognitive Neuroscience, 18(7).Van Berkum, J.J.A., Zwitserlood, P., Hagoort, P., & Brown, C.M. (2003). When and how do listeners relate a sentence to the wider discourse? Evidence from the N400 effect. Cognitive Brain Research, 17(3).
feed
could
Families
If cats are hungry they usually pester their owners until they get
fed.+
Fixation cross (500ms)
Context Sentence. Press spacebar to continue.
Blank screen (500ms)
Word by word target sentence (300ms)
Blank screen (200ms)
RESULTS
EXPERIMENT 1: COUNTERFACTUALS EXPERIMENT 2: NEGATION
N400 effect (largest in parietal areas):
RW & CW inconsistent more negative than consistent
RW inconsistent effect begins earlier than CW inconsistent
RW more negative than CW
Longer-lasting early positivity in CW-consistent condition (contains RW violation)
Topographic maps of ERP difference waveforms:Left panel: ERP difference (inconsistent minus consistent) for time range 350-500ms after critical noun onset Right panel: ERP difference (RW minus CW) for time range 350-500ms after critical noun onset
RESULTS
Topographic map of ERP difference waveforms:ERP difference (NW consistent minus NW inconsistent) for time range 350-500ms after critical noun onset
N400 effect (largest in parietal areas):
NW consistent (RW anomalous) more negative than NW inconsistent (RW congruent)
Longer-lasting early positivity in NW-consistent condition (contains RW violation)