Target-to-target interval influences a range of erp components
The amplitude of the late positive complex (LPC) of the event-related potential (ERP) is influenced by the target-to-target interval (TTI), with increases in TTI systematically enhancing LPC amplitudes. This study explored whether other ERP component amplitudes are affected by TTI in a similar manner. Electroencephalographic activity was recorded from 27 participants in a three-stimulus visual oddball task with equiprobable targets and infrequent nontargets, and frequent standards. We manually identified component peak amplitudes relative to a 100 ms prestimulus baseline. The selection of these amplitudes was confirmed with a temporal principal components analysis. As hypothesised, LPC amplitudes were enhanced by longer TTIs. P2 evidenced a similar response profile, where increases in TTI linearly augmented P2 amplitudes. However, the same pattern of results was not apparent for N1, where amplitudes were not affected by interval. It was also found that N2 amplitude decreased as TTI increased. Taken together, these results suggest that some exogenous ERP components are responsive to changes in the timing of target stimuli in a similar fashion to that of the later endogenous component, the LPC. Hence, it could be argued that TTI variation influences the attention and working memory systems involved in processing target stimuli. Implications are discussed in relation to context- update and context-closure theories.
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