The dynamics of overt visual attention shifts evoke certain patterns of responses in eye and head movements. In this work, we detail novel findings regarding the interaction of eye gaze and head pose under various attention-switching conditions in complex environments and safety critical tasks such as driving. In particular, we find that sudden, bottom-up visual cues in the periphery evoke a different pattern of eye-head movement latencies as opposed to those during top-down, task-oriented attention shifts. In laboratory vehicle simulator experiments, a unique and significant (p < 0.05) pattern of preparatory head motions, prior to the gaze saccade, emerges in the top-down case. This finding is validated in qualitative analysis of naturalistic real-world driving data. These results demonstrate that measurements of eye-head dynamics are useful data for detecting driver distractions, as well as in classifying human attentive states in time and safety critical tasks.