Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Electrophysiological measurement of rapid shifts of attention during visual search


The perception of natural visual scenes that contain many objects poses computational problems that are absent when objects are perceived in isolation1. Vision researchers have captured this attribute of real-world perception in the laboratory by using visual search tasks, in which subjects search for a target object in arrays containing varying numbers of non-target distractor objects. Under many conditions, the amount of time required to detect a visual search target increases as the number of objects in the stimulus array increases, and some investigators have proposed that this reflects the serial application of attention to the individual objects in the array2,3. However, other investigators have argued that this pattern of results may instead be due to limitations in the processing capacity of a parallel processing system that identifies multiple objects concurrently4,5. Here we attempt to address this longstanding controversy by using an electrophysiological marker of the moment-by-moment direction of attention — the N2pc component of the event-related potential waveform — to show that attention shifts rapidly among objects during visual search.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: Stimuli and results from the first experiment.
Figure 2
Figure 3


  1. 1

    Mozer, M. C. The Perception of Multiple Objects (MIT Press, Cambridge, Massachusetts, 1991).

    Google Scholar 

  2. 2

    Treisman, A. Features and objects: The fourteenth Bartlett memorial lecture. Q. J. Exp. Psychol. 40, 201–237 (1988).

    CAS  Article  Google Scholar 

  3. 3

    Wolfe, J. M. Guided search 2.0: A revised model of visual search. Psychonomic Bull. Rev. 1, 202–238 (1994).

    CAS  Article  Google Scholar 

  4. 4

    Bundesen, C. Atheory of visual attention. Psychol. Rev. 97, 523–547 (1990).

    CAS  Article  Google Scholar 

  5. 5

    Duncan, J., Ward, R. & Shapiro, K. Direct measurement of attentional dwell time in human vision. Nature 369, 313–315 (1994).

    ADS  CAS  Article  Google Scholar 

  6. 6

    Luck, S. J. & Hillyard, S. A. Electrophysiological correlates of feature analysis during visual search. Psychophysiology 31, 291–308 (1994).

    CAS  Article  Google Scholar 

  7. 7

    Luck, S. J. & Hillyard, S. A. Spatial filtering during visual search: Evidence from human electrophysiology. J. Exp. Psychol. Hum. Percept. Perform. 20, 1000–1014 (1994).

    CAS  Article  Google Scholar 

  8. 8

    Luck, S. J., Girelli, M., McDermott, M. T. & Ford, M. A. Bridging the gap between monkey neurophysiology and human perception: An ambiguity resolution theory of visual selective attention. Cogn. Psychol. 33, 64–87 (1997).

    CAS  Article  Google Scholar 

  9. 9

    Wolfe, J. M. What can 1 million trials tell us about visual search? Psychol. Sci. 9, 33–39 (1998).

    Article  Google Scholar 

  10. 10

    McCarthy, G. & Wood, C. C. Scalp distributions of event-related potentials: An ambiguity associated with analysis of variance models. Electroencephalogr. Clin. Neurophysiol. 62, 203–208 (1985).

    CAS  Article  Google Scholar 

  11. 11

    Carrasco, M., Evert, D. L., Change, I. & Katz, S. M. The eccentricity effect: Target eccentricity affects performance on conjunction searches. Percept. Psychophys. 57, 1241–1261 (1995).

    CAS  Article  Google Scholar 

  12. 12

    Wolfe, J. M., O'Neill, P. & Bennett, S. C. Why are there eccentricity effects in visual search? Visual and attentional hypotheses. Percept. Psychophys. 60, 140–156 (1998).

    CAS  Article  Google Scholar 

  13. 13

    Townsend, J. T. Serial vs. parallel processing. Sometimes they look like Tweedledum and Tweedledee but they can (and should) be distinguished. Psychol. Sci. 1, 46–54 (1990).

    Article  Google Scholar 

Download references


This work was supported by grants from the National Institute of Mental Health, the National Science Foundation and the Human Frontier Science Program.

Author information



Corresponding author

Correspondence to Steven J. Luck.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Woodman, G., Luck, S. Electrophysiological measurement of rapid shifts of attention during visual search. Nature 400, 867–869 (1999).

Download citation

Further reading


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing