Modulation of alerting and orienting attention on spatial suppression

Spatial suppression is a phenomenon in which, for high-contrast stimuli, larger stimuli typically elicit weaker neural responses and produce worse perceptual performance compared to smaller stimuli. This phenomenon is thought to arise from inhibitory connections between neurons. Although recent studies have suggested that feedback connections from high areas can influence these inhibitory processes, implying that attention may modulate spatial suppression, direct evidence for such modulation remains scarce. In particular, the impact of an important component of attention, alerting, has been overlooked. The present study aimed to explore the effects of two distinct components of attention-alerting and orienting-on spatial suppression. Our results indicate that alerting enhances spatial suppression. Furthermore, upon isolating the influence of orienting after controlling for alerting levels, we discovered that the influence of orienting on spatial suppression is feature-dependent. Specifically, while orienting attention to orientation enhances spatial suppression, orienting to contrast does not elicit the same effect. Our results indicate that spatial suppression is a flexible processing mechanism subject to widespread high-level cognitive modulations.