Cueing Effects and Perceptual Merging in Spatial Attention: An Electrophysiological Study

In exogenous orienting, cueing of the to-be-attended stimulus by another one at the same location facilitates processing at short stimulus onset asynchronies. This early facilitation is deemed to be a robust phenomenon, however, its underlying mechanisms are under question. Krüger et al. (2014) explain early facilitation as a result of perceptual merging due to an interaction between feedforward and feedback projections. In the current study, neuronal dynamics in alpha oscillations was used to understand this interaction and clarify the role of perceptual merging. Contrary to expectations, the results confirmed the response inhibition hypothesis (Albares et al., 2011) that explains facilitation as disinhibition of the inhibitory bias in the cueing task. It is likely caused by high alertness that could facilitate the selection of information at a price of its quality. In this case, the response could be given before top-down corrections required for perceptual merging were performed.