Touchscreens have changed the way that we interact with technology, but they aren’t suitable for everything. For scrolling through webpages – no problem. For choosing items from a menu – a bit trickier, but easily doable. For extended periods of typing, for gaming and for other precision work? Much more difficult.
Using the sense of touch to provide feedback to a user is known as haptics, or haptic feedback. It is the lack of this that causes some of the issues with touchscreens – at least, that was the conventional wisdom. At its most basic, haptics involve something like a vibration when pressing on the screen; more advanced forms can actually replicate the feel of a physical button.
A research group at Aalto University in Finland has devised a theory as to why precision uses like gaming are so clumsy on screens. They believe that the lack of tactile feedback is not wholly to blame. The group instead focuses on issues with timing and input lag.
The lack of physical buttons and tactile feedback was thought to be critical before this work, said researcher Byungjoo Lee of the University. However, they found that unpredictable key press timing was just as important.
In an experiment, participants were asked to tap a touchscreen when a target appeared. Significant differences were found between response times using physical keys and a touch display. The researchers propose that there are three sources of error, which make timing with touchscreens ‘very hard.’
- 1. People are unable to keep their finger at a constant distance above the surface. The finger is always moving, and even a small movement changes our ability to time precisely. With a physical keyboard, the finger simply rests on the key without depressing it.
- 2. It is hard for the human neural system to predict when the touch event has been registered when touching a screen. Typically, software detects the touch when the finger hits the display, but users cannot sense this.
- 3. Even after the touch event has been registered, it needs to be processed by the application. The time this takes can change depending on the situation, creating another source of latency.
According to the research, touchscreens are most accurate when the touch event is registered when the contact area of the finger is at its largest. The group used this finding to show that timing performance can be improved ‘significantly’ by registering the touch event at a specific time.
Using the mobile game ‘Flappy Bird’ (which requires very accurate timing), the researchers wrote a computer model that can predict how many points a gamer is able to score.
Unfortunately, there is no easy solution for the problem of finger movement, implying that physical keys will always beat touchscreens in gaming.
The paper, which was presented in May, can be found here.
Haptics – and specifically lack of presence (when you wear a headset, you are no more than an observer) – are also a problem for VR. Several companies are working on increasing users’ ability to interface with virtual worlds, such as PowerClaw (which promises to deliver sensations like temperature changes to users) and Dexta Robotics (the DexMo can change its feedback based on the virtual object being touched). That is the subject of another column, however!
– Tom Allen
