The P300 signal is monotonically modulated by target saliency level irrespective of the visual feature domain

Abstract

Abstract Purpose Event related responses to infrequent and task‐relevant stimuli often include an attentional peak, the P300 component. This component is typically regarded as independent from the sensory modality, with amplitude depending on target occurrence probability. In this study, we investigated whether the P300 signal could similarly be modulated by the degree of perceptual difference across visual target properties. Methods We used an oddball block design with texture and colour as perceptual category features and a frequency ratio of 1:16. EEG/ERP responses were recorded from 68 channels in 9 healthy participants, matched for age and educational level. For the colour condition, 3 targets with increasing steps of categorical deviation in perceived redness from the standard stimulus were used. Concerning the texture segmentation condition, 3 targets with increasing spatial phase difference were chosen. Colour target patches were presented against a reference background of a standard additive primary red patch, and texture patches against a standard grating one with no phase segregation contrast. Results Repeated measure analysis results suggest a significant modulation of P300 amplitude target levels in midline central and parietal channels for both conditions. Significant Spearman correlations (positive with amplitude and negative with latency) support this order effect between target perceptual level and the P300 response. Conclusion We conclude that the amplitude and latency of the P300 response is monotonically modulated by saliency levels of distinct target categories.