Visual task complexity and eye movement patterns influence measures of human neurovascular coupling

•Simple visual tasks activate the posterior circulation most selectively.•Complex visual tasks robustly activate the posterior and middle circulation.•Complex visual tasks do not selectively activate the posterior circulation.•Varying visual target speed has little effect on posterior circulation activation.•Visual target amplitude impacts the selectivity for the posterior circulation. Human neurovascular coupling research conventionally aims to selectively activate the posterior circulation using a visual task. Different research groups use divergent visual tasks ranging in complexity and eye movement patterns with potential confounding effects. To understand the role of task complexity and eye movement patterns in neurovascular coupling, we performed a series of experiments with visual tasks ranging in complexity, eye speed, and eye movement amplitude. Greater task complexity significantly reduced selectivity for the posterior circulation. Greater task amplitude (i.e. larger eye movements) increased selectivity. These findings are important when interpreting and designing neurovascular coupling investigations.