The Time Course of Negative Priming

Hecke Schrobsdorff, Matthias Ihrke, J?rg Behrendt, Marcus Hasselhorn, J. Michael Herrmann

Research output: Contribution to journalArticlepeer-review

Abstract

Selective attention enables goal-directed behavior despite the permanent, immense input to the sensory system. Contradicting early speculations of an active attending and passive ignoring, the active nature of ignoring was revealed by the negative priming paradigm. We will describe our multi-level approach to reveal the temporal structure of negative priming. Accompanied by computational modeling, we run sophisticated psychological experiments and record and analyze EEG data.The common denominator of all negative priming paradigms is the simultaneous presentation of targets that have to be attended to, and distractors that are to be ignored. A slowdown in the response to a formerly ignored stimulus is labeled negative priming. Because of negative priming being robust and sensitive at the same time, a variety of different theoretical accounts have been developed. But until now none of the theoretical accounts is able to explain all aspects of the negative priming effect. In order to clarify the situation of diverging explanatory accounts, the time course of negative priming is crucial. The mechanisms postulated by the different theories act in different stages of trial processing. In order to advance the debate on theoretical accounts, we provide two quantitative implementations. First we take up a single theory of negative priming and build a minimal model producing realistic effects on the basis of the postulated mechanism. We show how the model can be extended to generate hypotheses in a more complex paradigm. The second computational approach is more ambitious with respect to the discussion about the applicability of the theories of negative priming in specific situations. We build a computational model comprising most of the mechanisms suspected to play a role in the neural processing in negative priming tasks. The outcome is not only a meta-model for negative priming, termed General Model, but in itself a simplified model of the brain as a framework for action selection based on perception. We address the trade-off between biological realism and understandability by modeling each assumed mechanism separately but keeping the internal dynamics of each of the corresponding layers very simple.The computational implementation of theories is accompanied by a series of behavioral experiments intended to decide about the temporal localization of the negative priming effect relative to the processing of a single trial. We present an EEG experiment that finds a similar modulation of the P300 for both negative as positive priming trials and a differentiation in the late positive complex which points to a late occurring of the negative priming effect. In a paradigm which requires a button press between stimulus identification and target selection phase, we locate negative priming in the later part of a trial as well. This remainder of a trial still contains both the target selection and response generation process. Therefore, we construct another trial splitting paradigm which now singles out the response generation phase. We finally find the devotion of negative priming to the target selection phase of a trial.
Original languageEnglish
JournalFrontiers in Computational Neuroscience
Issue number32
DOIs
Publication statusPublished - 2009

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