Abstract
The moment-to-moment amount of visual information received by our visual system is enormous. Nevertheless, not all visual information serves a purpose for our cognitive, emotional, social, and ultimately survival goals. Therefore, the brain employs a process called attention to select relevant information and to optimize its limited resources. Specifically, covert spatial attention—attending to a particular location in the visual field without eye movements—improves spatial resolution and paradoxically deteriorates temporal resolution. Even though the role of spatial attention in perception is unquestioned, the neural correlates underlying these attentional effects remain still elusive. Thus, in this work, we tested the predictions of a mechanistic model that explains these phenomena based on interactions between channels with different spatiotemporal sensitivities—viz., the magnocellular (transient) and parvocellular (sustained) channels. More specifically, our model postulates that spatial attention enhances activities in the parvocellular pathway thereby producing improved performance in spatial resolution tasks. The attentional enhancement of parvocellular activities leads to decreased magnocellular activities due to parvo-magno inhibitory interactions in the model. As a result, spatial attention hampers temporal resolution. We compared our model’s predictions to psychophysical data, testing the effects of spatial attention on spatial acuity tasks (Yeshurun & Carrasco, 1999) and temporal acuity tasks (Yeshurun & Levy, 2003). The results show that our model accounts for both attentional effects, i.e., the improved performance in spatial resolution tasks (R2=0.98) and the impaired performance in temporal resolution tasks (R2=0.95). This study provides computational evidence in support of parvo-magno inhibitory interactions as potential neural mechanisms to account for the effects of spatial attention on spatiotemporal perception.