28616
document
The instruction to refrain from blinking affects auditory P3 and N1 amplitudes . Often subjects have been instructed to refrain from blinking lest their evoked EEG potentials should be distorted . We studied whether these very instructions have any impact on P3 amplitude . Two tones were presented in random order , and subjects had to count the high-pitched tones . Half the subjects were instructed not to blink , whereas this instruction was omitted for the other subjects . Target tones evoked larger P3s than non-targets in the latter group but not in the former , in particular not in those subjects that actually blinked rarely . The groups also differed in their N1 amplitudes . These findings might be relevant to P3 studies working with patients and controls : the harder some frequently blinking subjects try to refrain from blinking , the smaller might become their P3 amplitudes . Omitting the instruction and using off-line blink subtraction procedures seems a viable alternative . This study was actually motivated by discrepant findings on the effects of the preceding tone sequence on P3 . These discrepancies could be largely resolved by the instructional variable , in conjunction with different tone intensities . It is suggested that subjects who are discouraged from blinking try to protect themselves against the arousing effects of stimuli .
28617
Intervention_Educational
refrain from blinking
28618
Intervention_Educational
refrain from blinking
28619
Intervention_Educational
instructed not to blink
28620
Intervention_Educational
subjects who are discouraged from blinking
28621
Outcome_Physical
auditory P3
28622
Outcome_Physical
N1 amplitudes
28623
Outcome_Physical
P3 amplitude
28624
Outcome_Physical
P3s
28625
Outcome_Physical
N1 amplitudes
28626
Outcome_Physical
P3 amplitudes
28627
Outcome_Physical
effects of the preceding tone sequence on P3
28628
Outcome_Physical
tone intensities
28629
Participant_Condition
not to blink