Readiness to respond in a target detection task: pre- and post-stimulus event-related potentials in normal subjects

A. Starr, P. Sandroni, H. J. Michalewski

Research output: Contribution to journalArticlepeer-review

51 Scopus citations


Brain potentials were recorded from 12 normal subjects engaged in an auditory target detection task (target stimulus probability of 0.2, stimulus rate of 1 every 2 sec) when instructions were (1) to press a response button with the thumb of the dominant hand to each target or (2) to keep a mental count of each target. A pre-stimulus slow negative potential was identified before every stimulus except non-targets immediately after targets. The amplitude of the pre-stimulus negativity was significantly affected by task instructions and was up to 4 times larger during the button press than the mental count condition. In contrast, the amplitudes and latencies of the event-related components (N100, P200, N200 and P300), when slow potentials were removed by filtering, were not different as a function of press or count instructions. The immediately preceding stimulus sequence affected both the amplitude and onset latency of the pre-stimulus negativity; both measures increased as the number of preceding non-targets increased. The amplitude of the pre-stimulus negative shift to targets also increased significantly as RT speed decreased. The major portion of the pre-stimulus negative potential is considered a readiness potential (RP) reflecting preparations to make a motor response. The amplitude of the RP during the target detection task did not significantly lateralize in contrast to the RP accompanying self-paced movements.

Original languageEnglish (US)
Pages (from-to)76-92
Number of pages17
JournalElectroencephalography and Clinical Neurophysiology/ Evoked Potentials
Issue number1
StatePublished - Jan 1995


  • Event-related potentials
  • P300
  • Reaction time
  • Readiness potentials
  • Target detection

ASJC Scopus subject areas

  • General Neuroscience
  • Clinical Neurology


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