What is navigation and why is it important?
Spatial navigation refers to the process of determining and maintaining a trajectory from one place to another. It is a complex ability that relies on numerous cognitive and perceptual processes, which can vary depending on whether an individual is in familiar surroundings or a new environment.
People rely on two reference frames or co-ordination systems when navigating: egocentric and allocentric. The egocentric reference frame is concerned with encoding spatial information from the person’s point of view. To spatially navigate the environment, the individual will be required to collect sensorimotor information that enables them to locate their position in space, understand where they are in relation to other objects (distance between them and the object) and their own self-motion. The egocentric reference frame is concerned with well-learned stimulus-response associations between a particular landmark and the bodily movement that is required in response to this landmark (turn left at the swimming pool and then right at the Day Centre). This process is involved in learning fixed routes and results in proceduralized learning. This means that on familiar routes, individuals are likely to use automatic learned responses when encountering particular familiar landmarks.
Conversely, the allocentric reference frame is based on non-self-centred maps. These are ‘cognitive-maps’ that are stored in long-term memory, and enable a person to flexibly navigate their environment (as opposed to more proceduralized learning). Using this reference framework, an individual is able to flexibly choose how to proceed at a given decision point depending on their goals or internal states. For instance if they are hungry they can turn left to get to the restaurant, or if they require the toilet they could turn right. These cognitive maps contain information about the spatial relationship between locations, places and landmarks in the world, as opposed to information between the navigator and these places, locations and landmarks (as is the case with egocentric framework). These cognitive maps provide a representation of spatial information that does not change as the person moves through the environment. The allocentric frame of reference enables an individual to plan using a shorter path and to become orientated to unseen goal locations by relying on distance cues that are independent of themselves.
Both allocentric and egocentric strategies co-exist while an individual moves within an environment. Individuals who are good at navigating will be able to switch from one reference frame to another depending on the best approach for the situation they are faced with. Being able to navigate both familiar and new environments is a fundamental requirement of day-to-day life. Those who struggle to self-navigate will often require the support of external aids to do so (such as other people or Assistive Technological devices), and this can have detrimental consequences for their independence and subsequently their sense of self-worth.
What is the impact of dementia on an individual’s navigational abilities?
Throughout the ageing process, research has demonstrated that structural changes occur within specific areas of the brain that can adversely impact on an individual’s navigational ability. This includes shrinkage in the frontal structures of the brain and the whole striatum (typically impacting on egocentric strategies) as well as a reduction in the volume of the hippocampus (associated with allocentric strategies and spatial learning more generally). Within people living with mild cognitive impairment and dementia however, these navigational differences are more pronounced due to lesions in the brain. For instance, topographical disorientation (mapping of areas or localities) is one of the most common issues in people with Alzheimer’s Disease and is considered one of the first symptoms of the condition.
People with Alzheimer’s Disease have particular problems with learning unfamiliar environments (likely caused by hippocampal neurodegeneration). Specific navigational difficulties they may face are:
- Recall of pre-learned routes, assessing direction and route drawing on a map
- Landmark recognition, landmark location on 2D maps, free recall of landmarks encountered and recall of temporal order of landmarks
- Perception of visual motion (rather than memory impairment) leading to poor performance in topographical orientation, driving tests and route learning tasks
- Allocentric and egocentric strategies leading to issues with creating and using cognitive maps of an environment and computing body-centred information for self-orientation
- Spatial short-term memory and preserved spatial perception
How can navigation-based Serious Games be used with people with dementia?
Performances on navigation tasks in real world settings have been found to correlate highly with performances in virtual reality (VR). This means that computerised tasks and Serious Games, where environments can be more easily manipulated and rigorously controlled, are preferred as a medium to better understand the navigational difficulties that people with dementia may encounter in their daily lives. Researchers and practitioners are using these VR tasks and Serious Games to enable them to monitor an individual’s navigational performances as they age. This enables them to detect the possible early on-set of dementia (or Alzheimer’s Disease more specifically) as well as explore, and suggest ways for policy makers to enhance the independence of people living with the condition through creating supportive dementia-friendly environments (such as designing appropriate landmarks and signage to support navigation and orientation both in an outdoor environment and a care home). These improvements in design layout can compensate for impaired abilities and reduce disorientation for those with dementia. This would improve people’s quality of life and wellbeing, allow for the highest possible degree of independence to be maintained, reduce the work load of care partners and health professionals, and ease the transition of moving into care-homes (if this is required).
Serious Games that are available on this website and enable people to use their navigation and orientation abilities are: