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Abstract:
Abstract: As search speed is modulated by the precision of
precues to target location (Greenwood et al., 1997; Greenwood &
Parasuraman, 1999), we sought to determine which ERP components
reflect the neural activity associated with this attentional
scaling. Target-evoked ERPs were recorded from 16 young
participants during a visual discrimination task in which the
varying location of a vertical crescent target was precued (3 SOA:
230-350, 500-650, 800-950 msec) with rectangles varying over three
sizes. RT increased with cue size but SOA had little effect.
Behavioral effects of precue size and cue-target SOA on spatial
attention were largely consistent with our previous work, in which
we interpret the scaling effect to reflect top-down processing. P1
amplitude increased with cue-size at a short SOA, whereas N1
amplitude tended to decrease as cue-size increased. Larger precues
were associated with smaller P3 amplitude. P3 peak latency was
longer with larger cue size and shorter SOA. This may reflect
greater task difficulty under those conditions. The occipital P1,
the earliest stage of visual processing, appears to be modulated by
top-down information about the size of the area to be searched.
Evidence of separate modulation of P1, N1, and P3 suggests several
cortical areas may be important in attentional scaling. (NIA
AG07569, NIA AG12387 & NASA NAG3-2103)
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