Why interaction in motion is hard

Designing systems and user interfaces for active use during movement is hard. If we lose the assumption that a user is always standing still and able to pay full attention to our interface, interface design suddenly has to cope with a far wider range of situations.

This page contains a preliminary and non exhaustive list of some challenges created by movement interaction.

Using a mobile phone can impair your driving

Movement and attention
Numerous studies of use of technology in cars, such as sat nav devices and mobile phones, have shown that our ability to pay attention to driving cars as well as interacting with a device is limited. Focusing on the device can reduce our ability to respond to events occurring on the road, and cause safety issues. This issue of a limited ability to pay attention to multiple activities generalises to other types of movement – for example if we are running hard it is harder to pay attention to interactive systems, and if we are paying attention to an interactive system, it is harder to give our full attention to what we are running over.

Hands not free to interact

Physical constraints of movement
Movement activities can be physically constraining in ways which limit our ability to interact with devices whilst moving. This can be for several reasons: In some activities, the activity itself demands some kind of physical manipulation of equipment, such as bike handlebars, car steering wheels or ski poles; the way in which we are currently moving may reduce or increase the amount we are constrained to manipulating this equipment at any point. As well as equipment, there are elements of physical form inherent in movement activities that constrain interaction with interactive devices, for example when swimming with a full body stroke, the movement of our entire body is constrained by the stroke, there is an extremely small amount of leeway available for physical interaction with a device. Even in running, an activity where much of the body is relatively unconstrained, the need to look ahead, coupled with the need to move ones arms to run efficiently makes current interactive devices such as mobile phones hard to use whilst running (or even whilst walking fast).

Failure to interact on uneven terrain

Physical, digital and social terrain
When we are moving, the terrain we are moving over has a large amount of impact on how much we are able to pay attention to a device, and how physically constrained our movements are. For example in the picture to the left, I was foolish to run up a rocky path whilst using my phone, as I clearly was unable to pay sufficient attention to the phone and the terrain I was moving across. I also really required my hands free to balance whilst running up a steep and slippery path of rocks and mud. In many activities, such as swimming, or even walking in wet weather, the terrain in which the activity is being performed may be actively hostile to electronic devices. Terrain also has a (normally invisible) digital element, network connectivity, access to location services such as GPS, amounts of electrical lighting and even access to electrical power being very much location dependent. Social factors relating to locations may also create a further level of ‘terrain'; social factors such as crime rates or our familiarity with an area may have a large amount of influence on how willing we are to openly interact with an expensive device. Designing for movement means designing to take account of the fact that all these factors may change whilst interactions are ongoing.

The Visceral nature of movement
As discussed, many movement activities are not purely used as ways of getting around, even when this is a secondary purpose, such as on a bike commute. People do them for the enjoyment of doing the activity in itself. A major element of this enjoyment can be the visceral, exciting nature of some movement activities. ‘Extreme sports’ such as downhill mountain biking and big wave surfing are very much focused on visceral thrills, but arguably many less extreme pastimes involving movement such as going for country walks are motivated by some kind of visceral enjoyment of the activity. Designing systems in particular for extreme activities requires us to build designs which are sensitive to this visceral element of the activity. This challenge very much builds on our work in the Mixed Reality Lab on ‘uncomfortable interactions’, in that it is typical in many extreme activities to push oneself deliberately beyond what would normally be considered comfortable, and our interactive systems must support this.