Objective: We demonstrate how newly emerging technology can be utilized to record head movements and extract robust performance metrics. Therefore we will attempt to show, for the first time that orientation of attention affects onset of head saccade.

Background: It is well documented that the appearance of novel visual targets outside our central field of view results in a deflection of gaze towards the appearing stimulus. Furthermore, it has been established that these shifts in gaze are generated through a combination of distinct head and eye movements. While eye saccades have been well characterized, the role of head movement in gaze displacement has been less studied.

Methods: A head mounted display (Oculus Rift DK2) was employed for simultaneous data collection and task presentation. Healthy control participants (mean age±SD: 25.3±2.6 years, n=32) completed a modified Posner task in which head movements towards validly- and invalidly-cued eccentric targets were employed as the response. Electrooculography was also recorded for comparison with head movement data. Invalid cues were presented in 20% of trials.

Results: A delay in onset of head movement was observed during invalid trials (compared to valid trials), both at group and individual level. Head turns were a mean of 57.4ms earlier during valid trials: a 16.3% reduction in onset latencies. This result is a novel representation of the behavioural impact or orientation of attention. Furthermore, a strong relationship between saccade onset and head movement onset was demonstrated at group and individual level. The ocular saccadic activity observed was typical for such a task and helps validate the corresponding head movement results.

Conclusions: Our results demonstrate that the current protocol can be employed to investigate the effects of covert orienting of attention through an ecologically valid movement-based response in cases where eye tracking may not be available. This work, to our knowledge represents the first time that onset of head movement has been investigated as the response for such a task in humans. Similar tasks could be created to measure the response of patients with movement disorders. It’s possible that the device could be employed as an intervention in itself, by creating novel rehabilitation tasks. *I.B. and B.Q. contributed equally to this work.

The data was presented at the Registrar’s Prize in Ireland in November 2015.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/orientation-of-attention-affects-onset-of-head-saccades-a-novel-representation-of-the-posner-cueing-effect/