Same bi-directional modulation of contrast appearance for voluntary presaccadic attention and involuntary exogenous attention
Different types of attention alter subjective visual perception in fundamentally distinct ways. Previous studies have focused on covert attention without concurrent eye movements, showing that covert exogenous (involuntary) attention enhances contrast appearance of low-contrast stimuli while diminishing that of high-contrast stimuli, whereas covert endogenous (voluntary) attention uniformly enhances contrast appearance. However, the attentional effect preceding saccadic eye movements, a critical component of natural vision, remain understudied. Here, we found that when participants voluntarily initiated saccades, presaccadic attention enhanced the appearance of low-contrast stimuli while attenuating the appearance of high-contrast stimuli (Experiment 1, N = 29 adults). This pattern is surprisingly similar to exogenous attention but distinct from endogenous attention. Notably, the presaccadic attentional attenuation effect accumulated gradually during saccade preparation and remained positively correlated with the exogenous attentional effect (Experiment 2, N = 24 adults). These findings suggest a shared mechanism between presaccadic and exogenous attention in shaping visual perception.