Optic flow, egocentric direction and walking

This research explored two aspects of visually guided walking (1) what is the role of optic flow in the recalibration of misperceived direction while walking, and (2) how does a change in perceived direction map onto a change in walking direction. Data from five studies investigating adaptation to displaced direction (by prism glasses) suggested the following. First, optic flow is important in the recalibration of perceived direction. Further, processing optic flow is attentionally demanding, such that when cognitive load is increased, recalibration decreases. The results also demonstrated that the timecourse of recalibration changed as a function of the presence, or absence, of optic flow. With regards to the relationship between egocentric direction and walking direction, we demonstrated that a change in visual straight ahead could be mapped onto a change in target-heading error. We found that this relationship held when we unpacked the data according to the direction of displacement to which observers were exposed. The important relationship between visually perceived direction and walking direction was also highlighted in a patient study, using patients whose perception of direction was endogenously shifted after a right hemisphere stroke. Taken together, the results of this thesis help to highlight the role of optic flow in the recalibration of perceived direction, and the role of perceived direction in the visual guidance of walking. It is argued that optic flow promotes rapid recalibration of visual direction, and that change in perceived visual straight ahead can be mapped onto a changed in walking direction

How to specify healthcare process improvements collaboratively using rapid, remote consensus-building: a framework and a case study of its application

Abstract: Background: Practical methods for facilitating process improvement are needed to support high quality, safe care. How best to specify (identify and define) process improvements – the changes that need to be made in a healthcare process – remains a key question. Methods for doing so collaboratively, rapidly and remotely offer much potential, but are under-developed. We propose an approach for engaging diverse stakeholders remotely in a consensus-building exercise to help specify improvements in a healthcare process, and we illustrate the approach in a case study. Methods: Organised in a five-step framework, our proposed approach is informed by a participatory ethos, crowdsourcing and consensus-building methods: (1) define scope and objective of the process improvement; (2) produce a draft or prototype of the proposed process improvement specification; (3) identify participant recruitment strategy; (4) design and conduct a remote consensus-building exercise; (5) produce a final specification of the process improvement in light of learning from the exercise. We tested the approach in a case study that sought to specify process improvements for the management of obstetric emergencies during the COVID-19 pandemic. We used a brief video showing a process for managing a post-partum haemorrhage in women with COVID-19 to elicit recommendations on how the process could be improved. Two Delphi rounds were then conducted to reach consensus. Results: We gathered views from 105 participants, with a background in maternity care (n = 36), infection prevention and control (n = 17), or human factors (n = 52). The participants initially generated 818 recommendations for how to improve the process illustrated in the video, which we synthesised into a set of 22 recommendations. The consensus-building exercise yielded a final set of 16 recommendations. These were used to inform the specification of process improvements for managing the obstetric emergency and develop supporting resources, including an updated video. Conclusions: The proposed methodological approach enabled the expertise and ingenuity of diverse stakeholders to be captured and mobilised to specify process improvements in an area of pressing service need. This approach has the potential to address current challenges in process improvement, but will require further evaluation

The role of discrepant retinal motion during walking in the realignment of egocentric space

Visually guided action relies on accurate perception of egocentric direction. Unfortunately, perceived direction easily becomes misaligned. How is this problem overcome? One theory (R. Held & S. J. Freedman, 1963) is that during self-movement the observer uses the relationship between anticipated and experienced sensory feedback as a source of information to maintain alignment. However, data supporting this theory is equivocal, and recent evidence appears contradictory. We reexamined the issue. We injected an error into perceived visual direction and then assessed realignment after a period of walking toward a target. We manipulated the sensory information available (presence of retinal motion, Experiment 1; presence of peripheral motion, Experiment 2) and found that as the amount of retinal motion was reduced (Experiments 1 and 2), realignment of perceived visual direction decreased. When we then (Experiment 3) removed the discrepancy between anticipated and experienced retinal motion, no realignment was observed. Our results provide evidence that a discrepancy between anticipated and experienced sensory feedback is an important source of information for the alignment of egocentric space, with retinal motion having a particular role in driving a realignment of perceived visual direction