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N170 ERPs could represent a logographic processing strategy in visual word recognition.

Simon G, Petit L, Bernard C, Rebaï M - Behav Brain Funct (2007)

Bottom Line: However, some studies reported a lexical frequency effect for this component particularly during word repetition that appears in contradiction with this prelexical orthographic step.Moreover alternating font repetitions slowed subject's responses in comparison to "simple" massive repetition.ERPs results evidenced larger N170 amplitude in the left hemisphere for frequent than both infrequent words and pseudowords during massive repetition.Moreover, when words were repeated with different fonts this N170 effect was not present, suggesting a visual locus for such a N170 frequency effect.

View Article: PubMed Central - HTML - PubMed

Affiliation: Groupe d'Imagerie Neurofonctionnelle, UMR 6194, CNRS CEA, Universities of Caen & Paris Descartes, GIP Cyceron, boulevard Henri Becquerel, 14074 Caen Cedex, France. simon@cyceron.fr

ABSTRACT

Background: Occipito-temporal N170 component represents the first step where face, object and word processing are discriminated along the ventral stream of the brain. N170 leftward asymmetry observed during reading has been often associated to prelexical orthographic visual word form activation. However, some studies reported a lexical frequency effect for this component particularly during word repetition that appears in contradiction with this prelexical orthographic step. Here, we tested the hypothesis that under word repetition condition, discrimination between words would be operated on visual rather than orthographic basis. In this case, N170 activity may correspond to a logographic processing where a word is processed as a whole.

Methods: To test such an assumption, frequent words, infrequent words and pseudowords were presented to the subjects that had to complete a visual lexical decision task. Different repetition conditions were defined 1--weak repetition, 2--massive repetition and 3--massive repetition with font alternation. This last condition was designed to change visual word shape during repetition and therefore to interfere with a possible visual strategy during word recognition.

Results: Behavioral data showed an important frequency effect for the weak repetition condition, a lower but significant frequency effect for massive repetition, and no frequency effect for the changing font repetition. Moreover alternating font repetitions slowed subject's responses in comparison to "simple" massive repetition.ERPs results evidenced larger N170 amplitude in the left hemisphere for frequent than both infrequent words and pseudowords during massive repetition. Moreover, when words were repeated with different fonts this N170 effect was not present, suggesting a visual locus for such a N170 frequency effect.

Conclusion: N170 represents an important step in visual word recognition, consisting probably in a prelexical orthographic processing. But during the reading of very frequent words or after a massive repetition of a word, it could represent a more holistic process where words are processed as a global visual pattern.

No MeSH data available.


Related in: MedlinePlus

ERPs results for the weak repetition. A. Histograms represent N170 mean amplitudes averaged for T5-PO5 temporal electrodes at the left (LH) and T6-PO6 at the right hemisphere (RH). B. ERPs obtained for the first and the second presentation of the three lists of 50 stimuli. All ERPs illustrations corresponded to T5 electrode.
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Figure 4: ERPs results for the weak repetition. A. Histograms represent N170 mean amplitudes averaged for T5-PO5 temporal electrodes at the left (LH) and T6-PO6 at the right hemisphere (RH). B. ERPs obtained for the first and the second presentation of the three lists of 50 stimuli. All ERPs illustrations corresponded to T5 electrode.

Mentions: At temporal locations (figure 4A), an interaction between the stimulus type, the repetition and the hemisphere was evidenced (F2,18 = 5.48, p < .05). It corresponded to a larger negativity for the second presentation in comparison to the first one that was specific to frequent words (figure 4B) and observed only in left hemisphere (p < .001). Despite this strong repetition effect on frequent words, post-hoc analysis evidenced no significant word frequency effect on N170.


N170 ERPs could represent a logographic processing strategy in visual word recognition.

Simon G, Petit L, Bernard C, Rebaï M - Behav Brain Funct (2007)

ERPs results for the weak repetition. A. Histograms represent N170 mean amplitudes averaged for T5-PO5 temporal electrodes at the left (LH) and T6-PO6 at the right hemisphere (RH). B. ERPs obtained for the first and the second presentation of the three lists of 50 stimuli. All ERPs illustrations corresponded to T5 electrode.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC1884163&req=5

Figure 4: ERPs results for the weak repetition. A. Histograms represent N170 mean amplitudes averaged for T5-PO5 temporal electrodes at the left (LH) and T6-PO6 at the right hemisphere (RH). B. ERPs obtained for the first and the second presentation of the three lists of 50 stimuli. All ERPs illustrations corresponded to T5 electrode.
Mentions: At temporal locations (figure 4A), an interaction between the stimulus type, the repetition and the hemisphere was evidenced (F2,18 = 5.48, p < .05). It corresponded to a larger negativity for the second presentation in comparison to the first one that was specific to frequent words (figure 4B) and observed only in left hemisphere (p < .001). Despite this strong repetition effect on frequent words, post-hoc analysis evidenced no significant word frequency effect on N170.

Bottom Line: However, some studies reported a lexical frequency effect for this component particularly during word repetition that appears in contradiction with this prelexical orthographic step.Moreover alternating font repetitions slowed subject's responses in comparison to "simple" massive repetition.ERPs results evidenced larger N170 amplitude in the left hemisphere for frequent than both infrequent words and pseudowords during massive repetition.Moreover, when words were repeated with different fonts this N170 effect was not present, suggesting a visual locus for such a N170 frequency effect.

View Article: PubMed Central - HTML - PubMed

Affiliation: Groupe d'Imagerie Neurofonctionnelle, UMR 6194, CNRS CEA, Universities of Caen & Paris Descartes, GIP Cyceron, boulevard Henri Becquerel, 14074 Caen Cedex, France. simon@cyceron.fr

ABSTRACT

Background: Occipito-temporal N170 component represents the first step where face, object and word processing are discriminated along the ventral stream of the brain. N170 leftward asymmetry observed during reading has been often associated to prelexical orthographic visual word form activation. However, some studies reported a lexical frequency effect for this component particularly during word repetition that appears in contradiction with this prelexical orthographic step. Here, we tested the hypothesis that under word repetition condition, discrimination between words would be operated on visual rather than orthographic basis. In this case, N170 activity may correspond to a logographic processing where a word is processed as a whole.

Methods: To test such an assumption, frequent words, infrequent words and pseudowords were presented to the subjects that had to complete a visual lexical decision task. Different repetition conditions were defined 1--weak repetition, 2--massive repetition and 3--massive repetition with font alternation. This last condition was designed to change visual word shape during repetition and therefore to interfere with a possible visual strategy during word recognition.

Results: Behavioral data showed an important frequency effect for the weak repetition condition, a lower but significant frequency effect for massive repetition, and no frequency effect for the changing font repetition. Moreover alternating font repetitions slowed subject's responses in comparison to "simple" massive repetition.ERPs results evidenced larger N170 amplitude in the left hemisphere for frequent than both infrequent words and pseudowords during massive repetition. Moreover, when words were repeated with different fonts this N170 effect was not present, suggesting a visual locus for such a N170 frequency effect.

Conclusion: N170 represents an important step in visual word recognition, consisting probably in a prelexical orthographic processing. But during the reading of very frequent words or after a massive repetition of a word, it could represent a more holistic process where words are processed as a global visual pattern.

No MeSH data available.


Related in: MedlinePlus