Effect of temporal predictability on exogenous attentional modulation of feedforward processing in the striate cortex.
Non-informative peripheral visual cues facilitate extrastriate processing of targets [as indexed by enhanced amplitude of contralateral P1 event-related potential (ERP) component] presented at the cued location as opposed to those presented at uncued locations, at short cue-target stimulus onset asynchrony (SOA). Recently, two lines of research are emerging to suggest that the locus of attentional modulation is flexible and depends on 1) perceptual load and 2) temporal predictability of visual stimuli. We aimed to examine the effect of temporal predictability on attentional modulation of feed-forward activation of the striate cortex (as indexed by the C1 ERP component) by high-perceptual-load (HPL) stimuli. We conducted two ERP experiments where exogenously-cued HPL targets were presented under two temporal predictability conditions. In Experiment 1 [high-temporal-predictability (HTP) condition], 17 healthy subjects (age 18-26years) performed a line-orientation discrimination task on HPL targets presented in the periphery of the left upper or diagonally opposite right lower visual field, validly or invalidly cued by peripheral cues. SOA was fixed at 160ms. In Experiment 2 [low-temporal-predictability (LTP) condition], (n=10, age 19-36years) we retained HPL stimuli but randomly intermixed short-SOA trials with long-SOA (1000ms) trials in the task-blocks. In Experiment 1 and the short-SOA condition of the Experiment 2, validly-cued targets elicited significantly faster reaction times and larger contralateral P1, consistent with previous literature. A significant attentional enhancement of C1 amplitude was also observed in the HTP, but not LTP condition. The findings suggest that exogenous visual attention can facilitate the earliest stage of cortical processing under HTP conditions.
School of Psychology, The University of Newcastle, Callaghan, NSW 2308, Australia; Department of Physiology, Faculty of Medicine, University of Peradeniya, Peradeniya 20400, Sri Lanka. Electronic address: tharakad@pdn.ac.lk.
Tharaka L
TL
Dassanayake
School of Psychology, The University of Newcastle, Callaghan, NSW 2308, Australia; Priority Research Centre for Brain and Mental Health Research, The University of Newcastle, Callaghan, NSW 2308, Australia. Electronic address: Pat.Michie@necastle.edu.au.
Patricia T
PT
Michie
Priority Research Centre for Brain and Mental Health Research, The University of Newcastle, Callaghan, NSW 2308, Australia; School of Medicine and Public Health, Faculty of Health and Medicine, The University of Newcastle, Callaghan, NSW 2308, Australia. Electronic address: Ross.Fulham@newcastle.edu.au.
Ross
R
Fulham
D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D001288:Attention / Q000502:physiology*; D001931:Brain Mapping; D003463:Cues; D004569:Electroencephalography; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D010775:Photic Stimulation; D011237:Predictive Value of Tests; D011930:Reaction Time / Q000502:physiology; D014793:Visual Cortex / Q000502:physiology*; D014794:Visual Fields / Q000502:physiology; D014796:Visual Perception / Q000502:physiology*; D055815:Young Adult
C1; Event-related potentials; Perceptual load; Striate cortex; Temporal predictability; Visual attention