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Filling Predictable and Unpredictable Gaps, with and without Similarity-Based Interference: Evidence for LIFG Effects of Dependency Processing.

Leiken K, McElree B, Pylkkänen L - Front Psychol (2015)

Bottom Line: Half of the stimuli invoked similarity-based interference and half did not.Our results demonstrate that LIFG effects of dependency can be elicited regardless of whether the dependency is predictable, the stimulus materials evoke similarity-based interference, or the filler precedes the gap.Additionally, the millisecond time-resolution of MEG allowed for a detailed characterization of the temporal profiles of LIFG dependency effects across our three constructions, revealing that the timing of these effects is somewhat construction-specific.

View Article: PubMed Central - PubMed

Affiliation: Department of Linguistics, New York University, New York NY, USA ; Division of Neurology, MEG Center, Cincinnati Children's Hospital Medical Center, Cincinnati OH, USA.

ABSTRACT
One of the most replicated findings in neurolinguistic literature on syntax is the increase of hemodynamic activity in the left inferior frontal gyrus (LIFG) in response to object relative (OR) clauses compared to subject relative clauses. However, behavioral studies have shown that ORs are primarily only costly when similarity-based interference is involved and recently, Leiken and Pylkkänen (2014) showed with magnetoencephalography (MEG) that an LIFG increase at an OR gap is also dependent on such interference. However, since ORs always involve a cue indicating an upcoming dependency formation, OR dependencies could be processed already prior to the gap-site and thus show no sheer dependency effects at the gap itself. To investigate the role of gap predictability in LIFG dependency effects, this MEG study compared ORs to verb phrase ellipsis (VPE), which was used as an example of a non-predictable dependency. Additionally, we explored LIFG sensitivity to filler-gap order by including right node raising structures, in which the order of filler and gap is reverse to that of ORs and VPE. Half of the stimuli invoked similarity-based interference and half did not. Our results demonstrate that LIFG effects of dependency can be elicited regardless of whether the dependency is predictable, the stimulus materials evoke similarity-based interference, or the filler precedes the gap. Thus, contrary to our own prior data, the current findings suggest a highly general role for the LIFG in dependency interpretation that is not limited to environments involving similarity-based interference. Additionally, the millisecond time-resolution of MEG allowed for a detailed characterization of the temporal profiles of LIFG dependency effects across our three constructions, revealing that the timing of these effects is somewhat construction-specific.

No MeSH data available.


Trial structure.
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Figure 1: Trial structure.

Mentions: Before the MEG recordings, participants were instructed about the experimental task and their head shapes were digitized using a Polhemus (Colchester, VT, USA) FastSCAN COBRA 3D laser system. During the experiment, participants lay in a dimly lit, magnetically shielded room (Vacuumschmelze, Hanau, Germany). Using PsychToolbox, the experiment was presented on a 7x7-inch screen with a resolution of 1024 × 768 pixels placed approximately 9.5 inches above the subjects’ eyes. Stimuli were presented word by word, 300 ms for each word, with a 300 ms blank screen between each word. To allow for longer processing time of complex stimuli, a blank screen was then presented for 700 ms prior to the question screen. Using a button press, the subject expressed whether the answer to the comprehension question was “yes” or “no” (Figure 1). Trial order was random. Subjects were in the machine for an hour, with five breaks (between each of the six blocks), and were then given an extended break outside of the MEG room, due to the length of the study. Subjects then returned to the machine for the next six blocks. The entire recording took about 2.5 h. MEG data were collected using a using a whole-head 157-channel axial gradiometer system (Kanazawa Institute of Technology, Nonoichi, Japan). For this study, data were recorded at a sampling rate of 1000 Hz with a low-pass filter at 200 Hz using a DC recording and a notch filter at 60 Hz. Eye-blinks were recorded using an SR Research Eyelink 1000 Arm-Mounted Eyetracker sampling at 1000 Hz.


Filling Predictable and Unpredictable Gaps, with and without Similarity-Based Interference: Evidence for LIFG Effects of Dependency Processing.

Leiken K, McElree B, Pylkkänen L - Front Psychol (2015)

Trial structure.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4644799&req=5

Figure 1: Trial structure.
Mentions: Before the MEG recordings, participants were instructed about the experimental task and their head shapes were digitized using a Polhemus (Colchester, VT, USA) FastSCAN COBRA 3D laser system. During the experiment, participants lay in a dimly lit, magnetically shielded room (Vacuumschmelze, Hanau, Germany). Using PsychToolbox, the experiment was presented on a 7x7-inch screen with a resolution of 1024 × 768 pixels placed approximately 9.5 inches above the subjects’ eyes. Stimuli were presented word by word, 300 ms for each word, with a 300 ms blank screen between each word. To allow for longer processing time of complex stimuli, a blank screen was then presented for 700 ms prior to the question screen. Using a button press, the subject expressed whether the answer to the comprehension question was “yes” or “no” (Figure 1). Trial order was random. Subjects were in the machine for an hour, with five breaks (between each of the six blocks), and were then given an extended break outside of the MEG room, due to the length of the study. Subjects then returned to the machine for the next six blocks. The entire recording took about 2.5 h. MEG data were collected using a using a whole-head 157-channel axial gradiometer system (Kanazawa Institute of Technology, Nonoichi, Japan). For this study, data were recorded at a sampling rate of 1000 Hz with a low-pass filter at 200 Hz using a DC recording and a notch filter at 60 Hz. Eye-blinks were recorded using an SR Research Eyelink 1000 Arm-Mounted Eyetracker sampling at 1000 Hz.

Bottom Line: Half of the stimuli invoked similarity-based interference and half did not.Our results demonstrate that LIFG effects of dependency can be elicited regardless of whether the dependency is predictable, the stimulus materials evoke similarity-based interference, or the filler precedes the gap.Additionally, the millisecond time-resolution of MEG allowed for a detailed characterization of the temporal profiles of LIFG dependency effects across our three constructions, revealing that the timing of these effects is somewhat construction-specific.

View Article: PubMed Central - PubMed

Affiliation: Department of Linguistics, New York University, New York NY, USA ; Division of Neurology, MEG Center, Cincinnati Children's Hospital Medical Center, Cincinnati OH, USA.

ABSTRACT
One of the most replicated findings in neurolinguistic literature on syntax is the increase of hemodynamic activity in the left inferior frontal gyrus (LIFG) in response to object relative (OR) clauses compared to subject relative clauses. However, behavioral studies have shown that ORs are primarily only costly when similarity-based interference is involved and recently, Leiken and Pylkkänen (2014) showed with magnetoencephalography (MEG) that an LIFG increase at an OR gap is also dependent on such interference. However, since ORs always involve a cue indicating an upcoming dependency formation, OR dependencies could be processed already prior to the gap-site and thus show no sheer dependency effects at the gap itself. To investigate the role of gap predictability in LIFG dependency effects, this MEG study compared ORs to verb phrase ellipsis (VPE), which was used as an example of a non-predictable dependency. Additionally, we explored LIFG sensitivity to filler-gap order by including right node raising structures, in which the order of filler and gap is reverse to that of ORs and VPE. Half of the stimuli invoked similarity-based interference and half did not. Our results demonstrate that LIFG effects of dependency can be elicited regardless of whether the dependency is predictable, the stimulus materials evoke similarity-based interference, or the filler precedes the gap. Thus, contrary to our own prior data, the current findings suggest a highly general role for the LIFG in dependency interpretation that is not limited to environments involving similarity-based interference. Additionally, the millisecond time-resolution of MEG allowed for a detailed characterization of the temporal profiles of LIFG dependency effects across our three constructions, revealing that the timing of these effects is somewhat construction-specific.

No MeSH data available.