The effects of interstimulus interval on event-related indices of attention: an auditory selective attention test of perceptual load theory.
OBJECTIVE
We examined the impact of perceptual load by manipulating interstimulus interval (ISI) in two auditory selective attention studies that varied in the difficulty of the target discrimination.


METHODS
In the paradigm, channels were separated by frequency and target/deviant tones were softer in intensity. Three ISI conditions were presented: fast (300ms), medium (600ms) and slow (900ms). Behavioral (accuracy and RT) and electrophysiological measures (Nd, P3b) were observed.


RESULTS
In both studies, participants evidenced poorer accuracy during the fast ISI condition than the slow suggesting that ISI impacted task difficulty. However, none of the three measures of processing examined, Nd amplitude, P3b amplitude elicited by unattended deviant stimuli, or false alarms to unattended deviants, were impacted by ISI in the manner predicted by perceptual load theory.


CONCLUSIONS
The prediction based on perceptual load theory, that there would be more processing of irrelevant stimuli under conditions of low as compared to high perceptual load, was not supported in these auditory studies.


CONCLUSIONS
Task difficulty/perceptual load impacts the processing of irrelevant stimuli in the auditory modality differently than predicted by perceptual load theory, and perhaps differently than in the visual modality.
Gomes
Hilary
H
Psychology Department, City College of New York, CUNY, 138th and Convent Avenue, New York, NY, 10031, USA; Cognitive Neuroscience Subprogram, The Graduate Center of CUNY, 365 Fifth Avenue, New York, NY, 10016, USA. Electronic address: hgomes@earthlink.net.
Barrett
Sophia
S
Psychology Department, City College of New York, CUNY, 138th and Convent Avenue, New York, NY, 10031, USA; Cognitive Neuroscience Subprogram, The Graduate Center of CUNY, 365 Fifth Avenue, New York, NY, 10016, USA.
Duff
Martin
M
Psychology Department, City College of New York, CUNY, 138th and Convent Avenue, New York, NY, 10031, USA; Cognitive Neuroscience Subprogram, The Graduate Center of CUNY, 365 Fifth Avenue, New York, NY, 10016, USA.
Barnhardt
Jack
J
Cognitive Neuroscience Subprogram, The Graduate Center of CUNY, 365 Fifth Avenue, New York, NY, 10016, USA; Psychology Department, Wesley College, 120 North State Street, Dover, DE 19901, USA.
Ritter
Walter
W
Nathan S. Kline Institute for Psychiatric Research, 140 Old Orangeburg Road, Orangeburg, NY, 10962, USA.
D000161:Acoustic Stimulation / Q000379:methods; D000328:Adult; D000704:Analysis of Variance; D001288:Attention / Q000502:physiology*; D001307:Auditory Perception / Q000502:physiology*; D004192:Discrimination, Psychological; D004569:Electroencephalography / Q000379:methods; D018913:Event-Related Potentials, P300 / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D011582:Psychological Theory; D011930:Reaction Time / Q000502:physiology; D013997:Time Factors