This research has been made possible by a fellowship from the Royal Netherlands Academy of Arts and Sciences.
An ERP study of visual spatial attention and letter target detection for isoluminant and nonisoluminant stimuli
Article first published online: 30 JAN 2007
Volume 34, Issue 5, pages 553–565, September 1997
How to Cite
WIJERS, A. A., LANGE, J. J., MULDER, G. and MULDER, L. J. M. (1997), An ERP study of visual spatial attention and letter target detection for isoluminant and nonisoluminant stimuli. Psychophysiology, 34: 553–565. doi: 10.1111/j.1469-8986.1997.tb01742.x
We wish to thank Joop Clots. Edwin Kiers. Eisc Hockstra, and Jan Smit for technical support.
- Issue published online: 30 JAN 2007
- Article first published online: 30 JAN 2007
- (Received July 29, 1996; Accepted March 3, 1997)
- Spatial attention;
- Target detection;
- ERP topography
The event-related potential (ERP) effects of visual spatial attention and letter target detection for stimuli presented against a (nonisoluminant) dark background or against an isoluminant grey background were investigated. The goal was to study how the perceptual variable of luminance would influence early ERP reflections of selective attention. Such effects could further substantiate the claim that selective attention operates at the level of early perceptual processing and could provide evidence regarding the role of different visual routes in selective attention. Isoluminance increased the peak latency of the early ERP deflections (NP80, PI, and NI) by 40–50 ms. The ERP effects of spatial attention. consisting of PI and NI amplitude enhancements, were similarly delayed by isoluminance. supporting the idea that early selective processing is strongly dependent on bottom-up perceptual processing. P300 latency and reaction time were delayed by 70–75 ms, the additional delay probably reflecting that isoluminance affected decision processes in addition to perceptual processes. Isoluminance left the scalp topographies of the early ERP deflections largely unaffected, although a slight shift of the NI topography in the isoluminant condition toward more inferior lateral posterior regions of the scalp could have reflected an increased contribution from ventral (occipitotemporal) brain areas. Relative to nontarget letters, targels presented at both attended and unattended spatial positions elicited an early contralaterally dominant lateral occipitotemporal negativity (N2pc). This ERP component is proposed to reflect an early, partly automatic process of template matching, consistent with indications from spatiotemporal dipole modelling that the N2pc was generated in inferior occipitotemporal brain regions.