The effect of dual tasks in locomotor path integration.

Without landmarks, navigation is based on information about self-velocity, which is transformed to position or orientation by a process called path integration. Simple path integration tasks, such as reaching a previously seen goal by blindfolded locomotion, were often considered to be automatic and not influenced by unrelated cognitive activity. However, we recently showed that reproduction of self-motion without landmark cues exhibits systematic dual-task interference. Since these experiments did not exclude that the dual task only interferes with memory for self-motion, we performed two additional experiments testing generic path integration. We show that locomotor homing and reaching predefined goals by active self-motion are affected systematically by a concurrent mental task. The similarity of the effects we found to those reported for duration estimation led us to the hypothesis that subjective time may be used as a temporal basis of path integration. Alternatively, path integration and duration estimation may be based on similar underlying neuronal mechanisms, for example, coincidence detection in neural oscillators.