title: Attentional and sensory effects of lowered levels of intrinsic alertness.
abstract: Low levels of intrinsic alertness are associated with lateralized performance in visual tasks, similar to neglect of the left (ipsilesional) visual hemi-field. However, it is unclear whether reduced alertness produces a specific lateralization of spatial-attentional processes in terms of the prioritization of right- over left-side stimuli, or whether it affects more basic functions of visuo-sensory coding, and/or higher function of the top-down control of selection, of stimuli on the left side. To decide between these alternatives, the present study examined the effects of lowered alertness, induced by a 50-min vigilance task, in a partial-report paradigm of briefly presented letter displays. With only one (unilateral) stimulus in display, no specific hemi-field effects were found under low-alertness conditions, indicating that reduced alertness impairs neither sensory effectiveness nor the top-town control of selection. However, with dual, bilateral stimuli, report accuracy was specifically affected for left-side targets (in subjects who showed comparable performance for both sides under normal-alertness conditions). This pattern can be interpreted in terms of a specific bias in spatial-attentional weighting, where prioritization of stimuli on the right leads to (mild) extinction of targets on the left. Moreover, participants who had a lower general level of alertness also showed a more pronounced re-distribution of weights, evidenced by a more severe imbalance in report accuracy, in a low compared to a normal state of alertness. This suggests that a low general level of intrinsic alertness engenders a specific vulnerability to neglect-like performance with a (mild) left-side extinction.
authors.affiliation: General and Experimental Psychology, Ludwig-Maximilians-University, Leopoldstr. 13, 80802 Munich, Germany. matthias@psy.uni-muenchen.de
authors.forename: Ellen
authors.initials: E
authors.lastname: Matthias
authors.forename: Peter
authors.initials: P
authors.lastname: Bublak
authors.forename: Anna
authors.initials: A
authors.lastname: Costa
authors.forename: Hermann J
authors.initials: HJ
authors.lastname: Müller
authors.forename: Werner X
authors.initials: WX
authors.lastname: Schneider
authors.forename: Kathrin
authors.initials: K
authors.lastname: Finke
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001288:Attention / Q000502:physiology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D009949:Orientation / Q000502:physiology; D010775:Photic Stimulation / Q000379:methods; D011930:Reaction Time / Q000502:physiology; D012890:Sleep / Q000502:physiology; D013028:Space Perception / Q000502:physiology*; D013223:Statistics as Topic; D014794:Visual Fields / Q000502:physiology*; D055815:Young Adult