Abstract
BACKGROUND: The existence and function of unilateral hemispheric projections within foveal vision may substantially affect foveal word recognition. The purpose of this research was to reveal these projections and determine their functionality.
METHODOLOGY: Single words (and pseudowords) were presented to the left or right of fixation, entirely within either foveal or extrafoveal vision. To maximize the likelihood of unilateral projections for foveal displays, stimuli in foveal vision were presented away from the midline. The processing of stimuli in each location was assessed by combining behavioural measures (reaction times, accuracy) with on-line monitoring of hemispheric activity using event-related potentials recorded over each hemisphere, and carefully-controlled presentation procedures using an eye-tracker linked to a fixation-contingent display.
PRINCIPAL FINDINGS: Event-related potentials 100-150 ms and 150-200 ms after stimulus onset indicated that stimuli in extrafoveal and foveal locations were projected unilaterally to the hemisphere contralateral to the presentation hemifield with no concurrent projection to the ipsilateral hemisphere. These effects were similar for words and pseudowords, suggesting this early division occurred before word recognition. Indeed, event-related potentials revealed differences between words and pseudowords 300-350 ms after stimulus onset, for foveal and extrafoveal locations, indicating that word recognition had now occurred. However, these later event-related potentials also revealed that the hemispheric division observed previously was no longer present for foveal locations but remained for extrafoveal locations. These findings closely matched the behavioural finding that foveal locations produced similar performance each side of fixation but extrafoveal locations produced left-right asymmetries.
CONCLUSIONS: These findings indicate that an initial division in unilateral hemispheric projections occurs in foveal vision away from the midline but is not apparent, or functional, when foveal word recognition actually occurs. In contrast, the division in unilateral hemispheric projections that occurs in extrafoveal locations is still apparent, and is functional, when extrafoveal word recognition takes place.
| Original language | English |
|---|---|
| Article number | e23957 |
| Pages (from-to) | 1-9 |
| Number of pages | 10 |
| Journal | PLoS ONE |
| Volume | 6 |
| Issue number | 9 |
| DOIs | |
| Publication status | Published - 2011 |
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Keywords
- Adolescent
- Adult
- Behavior
- Brain Mapping
- Electroencephalography
- Evoked Potentials
- Fixation, Ocular
- Fovea Centralis
- Functional Laterality
- Humans
- Pattern Recognition, Visual
- Reaction Time
- Reading
- Reproducibility of Results
- Research Design
- Time Factors
- Vision, Ocular
- Visual Fields
- Journal Article
Cite this
An ERP assessment of hemispheric projections in foveal and extrafoveal word recognition. / Jordan, Timothy R; Fuggetta, Giorgio; Paterson, Kevin B; Kurtev, Stoyan; Xu, Mengyun.
In: PLoS ONE, Vol. 6, No. 9, e23957, 2011, p. 1-9.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - An ERP assessment of hemispheric projections in foveal and extrafoveal word recognition
AU - Jordan, Timothy R
AU - Fuggetta, Giorgio
AU - Paterson, Kevin B
AU - Kurtev, Stoyan
AU - Xu, Mengyun
PY - 2011
Y1 - 2011
N2 - BACKGROUND: The existence and function of unilateral hemispheric projections within foveal vision may substantially affect foveal word recognition. The purpose of this research was to reveal these projections and determine their functionality.METHODOLOGY: Single words (and pseudowords) were presented to the left or right of fixation, entirely within either foveal or extrafoveal vision. To maximize the likelihood of unilateral projections for foveal displays, stimuli in foveal vision were presented away from the midline. The processing of stimuli in each location was assessed by combining behavioural measures (reaction times, accuracy) with on-line monitoring of hemispheric activity using event-related potentials recorded over each hemisphere, and carefully-controlled presentation procedures using an eye-tracker linked to a fixation-contingent display.PRINCIPAL FINDINGS: Event-related potentials 100-150 ms and 150-200 ms after stimulus onset indicated that stimuli in extrafoveal and foveal locations were projected unilaterally to the hemisphere contralateral to the presentation hemifield with no concurrent projection to the ipsilateral hemisphere. These effects were similar for words and pseudowords, suggesting this early division occurred before word recognition. Indeed, event-related potentials revealed differences between words and pseudowords 300-350 ms after stimulus onset, for foveal and extrafoveal locations, indicating that word recognition had now occurred. However, these later event-related potentials also revealed that the hemispheric division observed previously was no longer present for foveal locations but remained for extrafoveal locations. These findings closely matched the behavioural finding that foveal locations produced similar performance each side of fixation but extrafoveal locations produced left-right asymmetries.CONCLUSIONS: These findings indicate that an initial division in unilateral hemispheric projections occurs in foveal vision away from the midline but is not apparent, or functional, when foveal word recognition actually occurs. In contrast, the division in unilateral hemispheric projections that occurs in extrafoveal locations is still apparent, and is functional, when extrafoveal word recognition takes place.
AB - BACKGROUND: The existence and function of unilateral hemispheric projections within foveal vision may substantially affect foveal word recognition. The purpose of this research was to reveal these projections and determine their functionality.METHODOLOGY: Single words (and pseudowords) were presented to the left or right of fixation, entirely within either foveal or extrafoveal vision. To maximize the likelihood of unilateral projections for foveal displays, stimuli in foveal vision were presented away from the midline. The processing of stimuli in each location was assessed by combining behavioural measures (reaction times, accuracy) with on-line monitoring of hemispheric activity using event-related potentials recorded over each hemisphere, and carefully-controlled presentation procedures using an eye-tracker linked to a fixation-contingent display.PRINCIPAL FINDINGS: Event-related potentials 100-150 ms and 150-200 ms after stimulus onset indicated that stimuli in extrafoveal and foveal locations were projected unilaterally to the hemisphere contralateral to the presentation hemifield with no concurrent projection to the ipsilateral hemisphere. These effects were similar for words and pseudowords, suggesting this early division occurred before word recognition. Indeed, event-related potentials revealed differences between words and pseudowords 300-350 ms after stimulus onset, for foveal and extrafoveal locations, indicating that word recognition had now occurred. However, these later event-related potentials also revealed that the hemispheric division observed previously was no longer present for foveal locations but remained for extrafoveal locations. These findings closely matched the behavioural finding that foveal locations produced similar performance each side of fixation but extrafoveal locations produced left-right asymmetries.CONCLUSIONS: These findings indicate that an initial division in unilateral hemispheric projections occurs in foveal vision away from the midline but is not apparent, or functional, when foveal word recognition actually occurs. In contrast, the division in unilateral hemispheric projections that occurs in extrafoveal locations is still apparent, and is functional, when extrafoveal word recognition takes place.
KW - Adolescent
KW - Adult
KW - Behavior
KW - Brain Mapping
KW - Electroencephalography
KW - Evoked Potentials
KW - Fixation, Ocular
KW - Fovea Centralis
KW - Functional Laterality
KW - Humans
KW - Pattern Recognition, Visual
KW - Reaction Time
KW - Reading
KW - Reproducibility of Results
KW - Research Design
KW - Time Factors
KW - Vision, Ocular
KW - Visual Fields
KW - Journal Article
U2 - 10.1371/journal.pone.0023957
DO - 10.1371/journal.pone.0023957
M3 - Article
VL - 6
SP - 1
EP - 9
JO - PLoS ONE
JF - PLoS ONE
SN - 1932-6203
IS - 9
M1 - e23957
ER -