Effect of task-irrelevant high-speed verbal stimulation on a visual/verbal word-discrimination task: an event-related potential study.
OBJECTIVE
We investigated whether incomprehensible high-speed auditory speech stimulation was processed and interacted with visual-word discrimination processing. We hypothesised that an interaction might indicate the capacity of working memory (WM) to perform the temporal processing of auditory verbal information.


METHODS
We recorded P300 for a visual-word discrimination Oddball paradigm in 14 healthy subjects. Auditory speech and reversed speech stimulation were presented at various speeds as task-irrelevant stimuli during the P300 tasks.


RESULTS
The P300 latency was prolonged under forward high-speed speech stimuli (× 2.5 and × 3.5) compared with the standard speed and white noise, but there was no effect of reversed speech stimuli on the P300 latency during the word-discrimination paradigm.


CONCLUSIONS
We considered that high-speed speech stimulation was processed without conscious comprehension and competed with verbal processing during the visual-word-discrimination task, possibly by interfering with the use of WM.


CONCLUSIONS
The present study shows the capacity of the brain to process high-speed verbal stimulation and the interaction with a visual-verbal task.
Uemura
Jun-ichi
J
Nagoya University, School of Health Sciences, 1-1-20 Daiko-Minami, Higashi-ku, Nagoya 461-8673, Japan.
Hoshiyama
Minoru
M
D000161:Acoustic Stimulation / Q000379:methods; D000704:Analysis of Variance; D001288:Attention / Q000502:physiology*; D001931:Brain Mapping; D004192:Discrimination, Psychological / Q000502:physiology*; D004569:Electroencephalography / Q000379:methods; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D010775:Photic Stimulation / Q000379:methods; D011930:Reaction Time / Q000502:physiology; D013997:Time Factors; D014825:Vocabulary; D055815:Young Adult