Dual-tasking: Is manual tapping independent of concurrently executed saccades?

Maintaining both spatial and temporal accuracy of concurrent motor actions is a challenging behavioral requirement in multi-tasking, where possible resource bottlenecks may become apparent when these units are shared between tasks. This study addresses the question of whether periodic self-paced finger movements (tapping) compulsorily interact with concurrently executed saccades, because they share some common neural control pathways. We employed a dual-task paradigm which was previously used to demonstrate strong interference between independent but concurrently conducted bimanual tapping tasks (Wachter, C., Cong, D.K., Staude, G., Wolf, W., 2008. Coordination of a discrete response with periodic finger tapping, additional experimental aspects for a subtle mechanism. J. Motor Behav. 40, 417-432). Instead of the discrete left hand response, the 13 participants now executed a single saccadic eye movement to a fixed visual target in parallel to continuous periodic tapping of the dominant hand. We expected these reactive saccades to act as a strong perturbation event to the continuous tapping, but the experimental data did not reveal a considerable interference in this specific oculo-manual dual-task experiment.

Attention and feature integration in the feature inheritance effect.

Features of neighboring elements are not processed independently. Often, it is assumed that nearby features are integrated by a (pre-attentive) pooling mechanism. Here, we show that in the feature inheritance effect some features are integrated across space whereas others are not. This result may be partly explained by a very focused spatial attention. Our findings challenge models based on a simple pooling mechanism.