Levels of visuo-spatial selection: an ERP study of negative priming.
Usually, a probe target appearing in a recently ignored distractor location is less efficiently processed. This robust phenomenon is called (visuo-) spatial negative priming (SNP). Among other explanations, concepts of persisting or retrieved spatial inhibition play a major role. Two relevant issues were investigated using event-related brain potentials (ERPs). The first pertains to context sensitivity of inhibition: Is a probe distractor necessary for SNP? The second concerns levels of processing at which spatial inhibition operates: Does SNP affect perception, selection, and/or stimulus classification? A localization task with and without probe distractors was employed while 64-channel EEG was recorded. Obviously, SNP does not require a probe distractor; the distractor-absent SNP effect was larger than the distractor-present SNP effect. Distractor-present SNP had two lateralized ERP effects, N1pc amplitude reduction and N2pc amplitude increase. Smaller N1pc may indeed reflect perceptual decrement, but was inversely related to size of behavioral SNP. By contrast, only strong-SNP participants showed N2pc increase, which points to selection disadvantage due to persisting inhibition of higher-level spatial representations. Distractor-absent SNP had no N1pc/N2pc correlates; instead, reduced amplitude of a broadly distributed P300 component suggests impaired stimulus classification due to episodic retrieval of inappropriate prime information. Overall, SNP seems to emerge from relatively late stages of processing, thus challenging the idea of context-free persisting inhibition of low-level spatial representations. Furthermore, distractor-present and distractor-absent SNP are qualitatively different from each other.
Institute for Psychology, Rheinische Friedrich Wilhelms University of Bonn, Bonn, Germany. Electronic address: hgibbons@uni-bonn.de.
Henning
H
Gibbons
Nancy
N
Wiegleb
Jutta
J
Stahl
D000293:Adolescent; D000328:Adult; D001288:Attention / Q000502:physiology; D001921:Brain / Q000502:physiology*; D018913:Event-Related Potentials, P300; D005074:Evoked Potentials, Visual; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008297:Male; D060865:Repetition Priming / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*; D055815:Young Adult
Event-related potentials; N1pc; N2pc; Negative priming; P300; Visuo-spatial selection