A.A. Wijers was sponsored by the Netherlands Organization for the Advancement of Pure Research (Z.W.O.).
Event-Related Potentials During Memory Search and Selective Attention to Letter Size and Conjunctions of Letter Size and Color
Article first published online: 30 JAN 2007
Volume 26, Issue 5, pages 529–547, September 1989
How to Cite
Wijers, A. A., Mulder, G., Okita, T. and Mulder, L. J.M. (1989), Event-Related Potentials During Memory Search and Selective Attention to Letter Size and Conjunctions of Letter Size and Color. Psychophysiology, 26: 529–547. doi: 10.1111/j.1469-8986.1989.tb00706.x
We thank Risto Näätänen, Walter Ritter, and two anonymous reviewers for commenting on a preliminary version of the manuscript.
- Issue published online: 30 JAN 2007
- Article first published online: 30 JAN 2007
- (Manuscript received June 24, 1988; accepted for publication November 17, 1988)
- Event-related potentials;
- Selective attention;
- Letter size;
- Conjunction of letter size and color;
- Memory search;
- Processing negativity;
- Search negativity
The analysis of event-related potentials was used in two experiments to investigate the structure of information processing in a task in which subjects selectively attended to letter size (Experiment 1) or a conjunction of letter size and color (Experiment 2) and searched for target letters within the attended stimulus category. The event-related potentials showed that selective attention to letter size resulted in the enhancement of a central N2b component (onset about 200 ms), which was assumed to reflect feature nonspecific orienting of attention. When attention was directed to conjunctions of letter size and color an earlier effect was found (onset about 150 ms) consisting of positivity at the anterior electrodes and negativity at Oz. This earlier effect was assumed to reflect feature-specific selective processing. Although the early effect showed a hierarchical pattern of results, in which the effect of attending to size was contingent on the relevance of the color attribute, the N2b showed a more independent pattern of results, in which the relevance of either the color or the size attribute resulted in an enhancement of this component, independent of the relevance of the other attribute. An increase in the duration of the memory search process resulted in a prolonged negativity with an onset of about 200 ms which was maximal at Cz. In both experiments the initial phase of this negativity was also found in the event-related potentials to the unattended stimulus categories, suggesting that the search process was initiated nonselectively and terminated after the selection cues were identified. Detection of attended target letters resulted in a parietal P3b component. In both experiments there was an earlier effect discriminating targets and nontargets in the range 200–300 ms.