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Kim & Osterhout (2005) JML. The independence of combinatory semantic processing: Evidence from event-related potentials. Background. Everyone believes N400 reflects semantic processing difficulty P600 reflects form-related processing difficulty
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Kim & Osterhout (2005) JML The independence of combinatory semantic processing: Evidence from event-related potentials Psyc / Ling / Comm 525 Fall 10
Background • Everyone believes • N400 reflects semantic processing difficulty • P600 reflects form-related processing difficulty • However, 2 studies have found P600 when they expected to find N400 • Kolk et al. (2003) found P600 at joeg • De vos die op de stropers joeg … • The fox that the poachers hunted … • = The fox that hunted the poachers … • Kuperberg et al. (2003) also found P600 at eat • For breakfast, the eggs would only eat … • In both cases, there was a noun that was plausible in some role of the verb’s event, just not the role its position indicated it had Psyc / Ling / Comm 525 Fall 10
Experiment 1 - Stimuli • Active Control • The hungry boy was DEVOURING the cookies. • Passive Control • The hearty meal was DEVOURED by the kids. • Anomaly • The hearty meal was DEVOURING the kids. Psyc / Ling / Comm 525 Fall 10
Procedures/Design • Sentences presented word-by-word centrally • SOA = 650 msec (slow!) • End-of-sentence acceptability judgments • Expt 1 • N = 24 • 96 sets of 3 sentence versions (32) • 107 distractors, some sem anom, some ungramm • Numbers varied across lists to make acceptability ~50/50 • 96 + 107 – 203 trials (58% acceptable, 42% unacceptable) • Expt 2 • N = 29 • 96 sets of 3 sentence versions (32) • 112 distractors, some sem anom, some ungramm • Numbers varied across list to make acceptability ~50/50 • 96 + 112 = 208 (50% acceptable, 50% unacceptable) Psyc / Ling / Comm 525 Fall 10
P600 P600 Experiment 1 - Results Psyc / Ling / Comm 525 Fall 10
Experiment 1 - Discussion • Why does “The hearty meal was devouring…” evoke P600 rather than N400? • Because hearty meal can play SOME thematic role in a devouring event? • Maybe the fact that hearty meal fits so well with devouring makes the processing system think there’s a grammatical error, like the wrong inflection on devouring, rather than a semantic anomaly Psyc / Ling / Comm 525 Fall 10
Experiment 2 - Stimuli • Passive Control • The hearty meal was DEVOURED … • No-attraction Violation • The dusty tabletops were DEVOURING … • Attraction Violation • The hearty meal was DEVOURING … Psyc / Ling / Comm 525 Fall 10
Experiment 2 - Results N400 Psyc / Ling / Comm 525 Fall 10
Experiment 2 - Discussion • Argue that these results show that • Semantic processing can “drive” sentence comprehension • Rather than always having to wait for structural processing to give the relationships among words before their semantic combination can proceed Psyc / Ling / Comm 525 Fall 10
The Role of Prosody • Embedded Clause / Direct Object sentences can be disambiguated with prosodic phrasing • Acoustic correlates: • Pause • Pre-boundary lengthening • Pitch contour • Pitch reset • … Psyc / Ling / Comm 525 Fall 10
How does this kind of prosodic boundary marking influence sentence interpretation? • Example of DO Prosody • The basketball star accepted the contract… …because it paid so well. Example of Clause Prosody - The basketball star accepted … … the contract requires him to play every game. Psyc / Ling / Comm 525 Fall 10
Do speakers actually produce different prosody in DO and Clause structures? Gahl & Garnsey (2004) Psyc / Ling / Comm 525 Fall 10
Boundaries marked more strongly when Structure not consistent with Verb Bias Psyc / Ling / Comm 525 Fall 10
Using ERPs to Study Prosody • On-line nature of ERPs especially good for investigating immediate effects of prosody during spoken sentence processing • Steinhauer, Alter, & Friederici (1999) • Discovered a positive ERP component at prosodic boundaries • “Closure Positive Shift” (CPS) Psyc / Ling / Comm 525 Fall 10
Closure Positive Shift (CPS) Psyc / Ling / Comm 525 Fall 10 Steinhauer, Alter & Friederici (1999)
CPS • Demonstrated CPS with • Delexicalized speech (Steinhauer & Friederici 2001) • Jabberwocky sentences (Pannekamp et al. 2005) • Pseudosentences (Pannekamp et al. 2005) • Hummed sentences (Pannekamp et al. 2005) • Musical phrases (Knösche et al. 2005) • Commas in orthographic stimuli (Steinhauer 2003; described in Frazier, Carlson, & Clifton 2006) • But only for people with good knowledge of comma rules Psyc / Ling / Comm 525 Fall 10
CPS Studies from Other Labs • Kerkhofs et al. (2007) • Embedded stimuli in discourses • Found smaller CPS when discourse made a boundary highly predictable • Casts some doubt on CPS as “pure prosody” processing Psyc / Ling / Comm 525 Fall 10
ERP Prosody Study(Jackson, Patel, & Garnsey, 2010) • Structure of sentence completion • Beginnings ambiguous The basketball star accepted the contract… • Direct Object (DO) ending …because it paid so well. • Embedded Clause (Clause) ending …requires him to play every game. • All Verbs DO-Bias & Critical Nouns plausible as DO • To maximize garden-pathing, to have the best possible chance to see whether prosody can prevent it Psyc / Ling / Comm 525 Fall 10
Stimuli • Prosodic Phrasing • Direct Object (DO) phrasing [ The basketball star accepted the contract ] [ because it paid so well. ] • Embedded Clause (EC) phrasing [ The basketball star accepted ] [ the contract requires him to play every game. ] Psyc / Ling / Comm 525 Fall 10
More Stimuli & Design • Fully crossed • Matching conditions: • DO ending + DO prosody [ The basketball star accepted the contract ] [ because it paid so well. ] • Clause ending + Clause prosody [ The basketball star accepted ] [ the contract requires him to play every game. ] Psyc / Ling / Comm 525 Fall 10
More Stimuli & Design • Mismatching conditions: • Clause ending + DO prosody [ The basketball star accepted the contract ] [ requires him to play every game. ] • DO ending + Clause prosody [ The basketball star accepted ] [ the contract because it paid so well. ] Psyc / Ling / Comm 525 Fall 10
Materials Construction • “Natural” recordings made in all four conditions. • From these, spliced: • One beginning per prosody condition • One ending per structure condition • Splice locations counterbalanced to ensure equivalent (un)naturalness across conditions Psyc / Ling / Comm 525 Fall 10
Splicing example • Beginnings • DO prosody • Clause prosody • Endings • DO ending • Clause ending • Results • DO prosody, DO ending • Clause prosody, DO ending • DO prosody, Clause ending • Clause prosody, Clause ending Psyc / Ling / Comm 525 Fall 10
ERP Data Analysis Predictions: • CPS when there’s a boundary compared to no boundary • No P600 when prosody could prevent garden-pathing Limitation on data analysis: Can’t directly compare across prosodic conditions at the critical disambiguating word (requires orbecause) • Because in DO Prosody, CPS directly precedes it, but not in SC Prosody (CPS earlier, after main verb accepted) • So compare difference waves across Structures within Prosody • ERP starting at end of pre-boundary word minus ERP starting at end of same word without boundary shows CPS Psyc / Ling / Comm 525 Fall 10
Structure Matches Boundary Location(collapsed over Clause & DO-Structure) Difference Waves: Boundary minus No-Boundary 0 msec = end of “pre-boundary” word Psyc / Ling / Comm 525 Fall 10
Structure MISmatches Boundary Location(collapsed over Clause & DO-Structure) Difference Waves: Boundary minus No-Boundary 0 msec = end of “pre-boundary” word Psyc / Ling / Comm 525 Fall 10
When Structure MatchesBoundary Location Psyc / Ling / Comm 525 Fall 10
When Structure MISmatchesBoundary Location Psyc / Ling / Comm 525 Fall 10
Next Steps • Manipulate Verb Bias • Manipulate Plausibility • Would a Boundary before a Noun that’s implausible as a DO prevent N400 effects on Noun? • The referees warned // the game would probably go into overtime. Psyc / Ling / Comm 525 Fall 10
Summing Up • Multiple sources of information constrain sentence interpretation • Lexical bias, plausibility, prosody … • The sources interact • BUT some provide stronger constraints • And/or are available more rapidly • And thus drive the interaction • And this all happens really fast! Psyc / Ling / Comm 525 Fall 10