The VESPA: A method for the rapid estimation of a visual evoked potential

Edmund C. Lalor, Barak A. Pearlmutter, Richard B. Reilly, Gary McDarby, John J. Foxe

Research output: Contribution to journalArticlepeer-review

90 Scopus citations


Faster and less obtrusive means for measuring a Visual Evoked Potential would be valuable in clinical testing and basic neuroscience research. This study presents a method for accomplishing this by smoothly modulating the luminance of a visual stimulus using a stochastic process. Despite its visually unobtrusive nature, the rich statistical structure of the stimulus enables rapid estimation of the visual system's impulse response. The profile of these responses, which we call VESPAs, correlates with standard VEPs, with r = 0.91, p < 10- 28 for the group average. The time taken to obtain a VESPA with a given signal-to-noise ratio compares favorably to that required to obtain a VEP with a similar level of certainty. Additionally, we show that VESPA responses to two independent stimuli can be obtained simultaneously, which could drastically reduce the time required to collect responses to multiple stimuli. The new method appears to provide a useful alternative to standard VEP methods, and to have potential application both in clinical practice and to the study of sensory and perceptual functions.

Original languageEnglish (US)
Pages (from-to)1549-1561
Number of pages13
Issue number4
StatePublished - Oct 1 2006
Externally publishedYes


  • EEG
  • Experimental design
  • Magnocellular
  • Striate cortex
  • System identification
  • Visual evoked potential

ASJC Scopus subject areas

  • Neurology
  • Cognitive Neuroscience


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