Differential and overlapping effects between exogenous and endogenous attention shape perceptual facilitation during visual processing

Visuospatial attention is not a monolithic process and can be divided into different functional systems. In this framework, exogenous attention reflects the involuntary orienting of attention resources following a salient event, whereas endogenous attention corresponds to voluntary orienting based on the goals and intentions of individuals. Previous work shows that these attention processes map onto distinct functional systems, yet evidence suggests that they are not fully independent. In the current work, we investigated the differential and overlapping effects of exogenous and endogenous on visual processing of sensory events. Specifically, we combined spatial cueing of visuospatial attention, electroencephalography (EEG), and multivariate pattern analysis (MVPA) to examine where and when the effects of exogenous and endogenous attention were maximally different and maximally similar. Critically, MVPA provided new insights by examining whether classifiers trained to decode the cueing effect for one attention process (e.g., exogenous attention) can successfully decode the cueing effect for the other attention process (e.g., endogenous attention), and vice versa. These analyses revealed differential effects between exogenous and endogenous early after target onset (<200ms post-target). In turn, both shared similar processing later (∼300ms post-target). We combined principal component analyses, single-trial event-related potentials, and mediation analysis to determine whether these effects contribute to the facilitation effects observed at the behavioral level after exogenous and endogenous spatial cueing. We uncovered that three EEG components (i.e., a posterior ipsilateral component, a posterior contralateral one, and a central one) shape the cueing effects of exogenous and endogenous attention at various times after target onset. Altogether, our study combines the strengths of MVPA, single-trial analysis, and meditation modelling to provide a comprehensive account about overlapping and differential processes of endogenous and exogenous, and how these dynamics relate to perceptual facilitation in the context of visuospatial attention. Significance Statement Top-down and bottom-up attention represent separate functional systems in the brain. Previous research suggests, however, that they are not fully independent, and can interfere with each other. In the present study, the authors use machine learning techniques and recordings of brain activity to investigate differences and similarities between top-down and bottom-up attention during the visual processing of stimuli. This approach allowed them to explore how top-down and bottom-up attention processes facilitate perception. Their results show that top-down and bottom-up attention operate differently as early as 100ms after the onset of a target. In contrast, they operate similarly 200ms after the target onset y. Most importantly, these effects are directly related to the participants’ perceptual behavior. In sum, our study shows that top-down and bottom-up attention support the perception of stimuli through overlapping and distinct spatio-temporal brain patterns.