Nicola Molinaro

Predictive mechanisms in idiom comprehension

Prediction is pervasive in human cognition and plays a central role in language comprehension. At an electrophysiological level, this cognitive function contributes substantially in determining the amplitude of the N400. In fact, the amplitude of the N400 to words within a sentence has been shown to depend on how predictable those words are: The more predictable a word, the smaller the N400 elicited. However, predictive processing can be based on different sources of information that allow anticipation of upcoming constituents and integration in context. In this study, we investigated the ERPs elicited during the comprehension of idioms, that is, prefabricated multiword strings stored in semantic memory. When a reader recognizes a string of words as an idiom before the idiom ends, she or he can develop expectations concerning the incoming idiomatic constituents. We hypothesized that the expectations driven by the activation of an idiom might differ from those driven by discourse-based constraints. To this aim, we compared the ERP waveforms elicited by idioms and two literal control conditions. The results showed that, in both cases, the literal conditions exhibited a more negative potential than the idiomatic condition. Our analyses suggest that before idiom recognition the effect is due to modulation of the N400 amplitude, whereas after idiom recognition a P300 for the idiomatic sentence has a fundamental role in the composition of the effect. These results suggest that two distinct predictive mechanisms are at work during language comprehension, based respectively on probabilistic information and on categorical template matching.

Consonants and Vowels Contribute Differently to Visual Word Recognition: ERPs of Relative Position Priming

This paper shows that the nature of letters--consonant versus vowel--modulates the process of letter position assignment during visual word recognition. We recorded Event Related Potentials while participants read words in a masked priming semantic categorization task. Half of the words included a vowel as initial, third, and fifth letters (e.g., acero [steel]). The other half included a consonant as initial, third, and fifth (e.g., farol [lantern]). Targets could be preceded 1) by the initial, third, and fifth letters (relative position; e.g., aeo-acero and frl-farol), 2) by 3 consonants or vowels that did not appear in the target word (control; e.g., iui-acero and tsb-farol), or 3) by the same words (identity: acero-acero, farol-farol). The results showed modulation in 2 time windows (175-250 and 350-450 ms). Relative position primes composed of consonants produced similar effects to the identity condition. These 2 differed from the unrelated control condition, which showed a larger negativity. In contrast, relative position primes composed of vowels produced similar effects to the unrelated control condition, and these 2 showed larger negativities as compared with the identity condition. This finding has important consequences for cracking the orthographic code and developing computational models of visual word recognition.

A deeper reanalysis of a superficial feature: An ERP study on agreement violations

A morphosyntactic agreement violation during reading elicits a well-documented biphasic ERP pattern (LAN+P600). The cognitive variables that affect both the amplitude of the two components and the topography of the anterior negativity are still debated. We studied the ERP correlates of the violation of a specific agreement feature based on the phonology of the critical word. This was compared with the violation of a lexical feature, namely grammatical gender. These two features are different both in the level of representation involved in the agreement computation and in terms of their role in establishing structural relations with possible following constituents. The ERP pattern elicited by the two agreement violations showed interesting dissociations. The LAN was distributed ventrally for both types of violation, but showed a central extension for the gender violation. The P600 showed an amplitude modulation: this component was larger for phonotactic violations in its late time window (700-900 ms). The former result is indicative of a difference in the brain structures recruited for the processing of violations at different levels of representation. The P600 effect is interpreted assuming a hierarchical relation among features that forces a deeper reanalysis of the violation involving a word form property. Finally the two features elicit distinct end-of-sentence wrap-up effects, consistent with the different roles they play in the processing of the whole sentence.

Anaphoric Agreement Violation: An ERP Analysis of Its Interpretation.

In the present study we analyzed the processing of grammatically anomalous sentences like The famous dancer were nervously preparing herself/themselves to face the crowd., which contains two anomalies, one early and one late. We investigated how processing of the later anomaly (at the pronoun herself or themselves) was affected by the processing of the early anomaly (at were). We considered two processing scenarios involving the first anomaly: (1) The representation of the subject-verb number agreement error at the first verb is coerced to match the verb, rendering herself anomalous; (2) The representation of the subject-verb agreement error is coerced to match the subject noun, rendering themselves anomalous. Our dependent measure was event-related scalp potentials (ERPs). When the pronoun disagreed with the verb (and agreed with the subject), a P600 was recorded, while the opposite condition elicited no reliable effect. Our data suggest that interpretation of reflexive pronouns involves the reactivation of multiple lexical items, verbs included.

From numbers to letters: feedback regularization in visual word recognition.

Word reading in alphabetic languages involves letter identification, independently of the format in which these letters are written. This process of letter regularization is sensitive to word context, leading to the recognition of a word even when numbers that resemble letters are inserted among other real letters (e.g., M4TERI4L). The present study investigates the electrophysiological correlates of number-to-letter regularization by means of the masked priming paradigm: target words (MATERIAL) were preceded by fully alphabetic primes (MATERIAL), primes with letter-like numbers (M4T3R14L), or primes with unrelated numbers (M7T6R28L). ERPs revealed three subsequent effects. Around 150 ms the unrelated numbers condition elicited a positive effect, compared to the other two conditions, in the occipital electrodes. Then, target words preceded by primes with numbers elicited a more negative N200 in the same electrodes compared to the fully alphabetic condition. Finally, both alphabetic primes and letter-like numbers elicited a posterior positive component peaking around 260 ms compared to unrelated numbers. Source analysis for each electrophysiological effect revealed a similar early increase of activity in the left occipito-temporal pathway for alphabetic primes and primes with letter-like numbers. Around 200 ms, the orthographic interference due to the numerical values correlated with an increase of activity in parietal areas; finally, a recursive effect in the left occipital cortex was found, reflecting abstract letter activation. These results indicate that direct feedback interaction from word units strongly influences the activation of the letter units at a format-independent abstract level.

Cloze probability does not only affect N400 amplitude: The case of complex prepositions

Cloze-probability levels are inversely correlated with N400 amplitude, indicating an easier integration for expected words in semantic-pragmatic contexts. Here we exploited the prespecified standard order of complex prepositions and measured the ERPs time-locked to the last preposition in sentences in which complex prepositions were presented in their standard form or with the last preposition changed. The expected preposition elicited an N280 followed by an N400-700, two ERP components previously associated to the processing of closed-class words. The unexpected preposition elicited only an N280, and the N400-700 was reduced. These results reflect the specificity of the contextual constraints linked to the complex preposition word sequence.

Aspettative semantiche ed espressioni idiomatiche: aspetti psicolinguistici ed evidenze elettrofisiologiche

In questo capitolo indagheremo il ruolo dei meccanismi di anticipazione semantica nella comprensione di espressioni i costituenti delle quali sono tipicamente legati fra loro in una sequenza piu o meno fissa, cioe le espressioni idiomatiche.1