Pattern for Human Machine Interaction

**A Pattern is ….
…a structured description of best practices/proven solutions to recurring problems within a given domain in an easy-to-understand, human-readable format.
…used in many areas (e.g., urban architecture, software design, interaction design or human-robot interaction)**

(Design) patterns capture useful design solutions and generalize these solutions to address similar problems.
In HCI, patterns are often used to convey principles and best practices of good interface design.
Adoption of the pattern approach for a variety of different fields in HCI – illustrates flexibility and broad applicability.
Up to now, no comprehensive pattern collection for collecting best practices on enhancing UX is existing.


**Structure of a cUX Pattern**

Contextual Car User Experience format*:

Name: main idea of the pattern in one or a few words
Intent: short statement
Topics: max. 8 keywords describing problem scope
Problem: detailed description
Scenario: example of a case, in which the problem occurs
Solution: general and alternative solutions
Examples: concrete examples
Reference Keywords: main topics addressed by the pattern
Sources: origin of the pattern, related literature


3 UX Factors:
Mental Workload Caused by Distraction
Perceived Safety
Joy of Use

Current status: Pattern collection covering all 3 UX Factors (50 patterns)



**Pattern No. 1**
*Voice as preferred interaction modality*
This pattern is about reducing mental workload when performing secondary tasks while driving by allowing the driver to use voice interaction as a less distracting interaction method for such tasks. Performing secondary tasks while driving causes additional workload and distraction for the driver. Which is the most appropriate interaction method to keep distraction at a minimum?

**Pattern No. 2**
*Reduced Distraction by Using a Multimodal Interface*
This pattern is about reducing mental workload when performing secondary tasks while driving by employing multi-modal input methods.
How can distraction of the driver be reduced when performing secondary tasks while driving?

**Pattern No. 3**
*Optimal Display Position*
This pattern is about effective display position for visual information presentation for the driver in order to reduce mental workload.
Information sources are spread throughout the cockpits of cars (instrument cluster, center console, in and around the steering wheel). Differently sized displays in different positions make it difficult for the driver to locate the right information at the right time, thus being a potential source of distraction for the driver.

**Pattern No. 4**
*Number of Displays*
This pattern is about the ideal number of displays for visual information presentation for the driver in order to reduce mental workload.
Displays are spread throughout the cockpits of cars (instrument cluster, middle console, above middle console, HUD, rear mirror). The focus of visual attention on a display inside the car that is far from the driver's normal line of sight causes longer reaction times to direct the gaze back to the road scene.

**Pattern No. 5**
*Steering Wheel Remote Control*
This pattern is about the positioning of controls within easy reach of the driver's hands in order to reduce mental workload.
Switching stations or adjusting loudness while driving is physically and mentally distracting, especially with the controls located in the center stack.

**Pattern No. 6**
*Situation-Adaptive Information Filtering*
This pattern is about reducing mental workload by filtering secondary task information dependent upon an estimation of a user's workload while driving. Dividing attention between the primary task of driving and secondary driver tasks, like using mobile phones, may cause driver information overload, which in turn can compromise traffic safety.

**Pattern No. 7**
*Intuitively used Voice User Interface*
This pattern is about a system-initiated, question-based approach to reduce distraction by voice user interfaces of driver information systems while driving. The problems of driver information systems with a voice user interface, which require user-initiative, are the steep learning curve and the high demand on memory to recall the correct voice commands. This can lead to elevated mental workload while driving.

**Pattern No. 8**
*Contextual Adaptive User Interface*
This pattern is about reducing the driver's distraction when driving while engaged in secondary tasks.
Drivers are often distracted from their primary task by IVIS. Driver distraction may occur when the driver is engaged in secondary tasks such entering a navigation goal or making a phone call whilst driving.

**Pattern No. 9**
*Influencing Emotionally Caused Distraction*
This pattern is about reducing distraction caused by the emotional state of the driver. Changing the "voice" of the car-announcements according to emotional state of the driver while driving can reduce distraction. Drivers' emotional state can affect driving performance. Just as users can have emotions, interfaces can manifest emotions. Voice interfaces can exhibit emotion through the tone of the voice. Therefore it is important to know how the users emotion and voice interface emotion interact to influence drivers' performance and attitude.

**Pattern No. 10**
*Interruptible / Resumable Secondary Tasks*
This pattern is about reducing distraction caused by secondary tasks by making the tasks interruptible and resumable while driving.
Users perform secondary tasks while driving. If the execution of these takes too long they might be distracted for a too long period of time from their driving task, leading to a higher risk of crashes.

**Pattern No. 11**
*Modified Map-Based Navigation Display*
This pattern is about reducing mental workload caused by an insufficient display precision of the surrounding area on the navigation system when reaching a final destination. Typical route summary features from GPS-based navigation systems such as maps often cause workload and distraction for the driver, because the display does not show details of the surrounding area. Usually the system states: "You have reached your destination", but does not display exactly where the destination is.

**Pattern No. 12**
*Modality-Choice for Presenting Hazard Warnings*
This pattern is about reducing mental distraction caused by non-driving tasks of the driver camouflaging hazard warnings.
Danger warnings can be camouflaged by other tasks of the driver. How can hazard warnings be optimized in order to shorten reaction time of drivers. In-vehicle messages and in particular local danger warnings are not effective enough or even not noticed by drivers.

**Pattern No. 13**
*Gesture Input on the Steering Wheel*
This pattern is about reducing distraction caused by haptic input into an onboard system located in the center-stack.
Drivers are often distracted through in-vehicle information systems that need for input in the central console. Interaction with a multifunctional controller or a touch display in the central console requires for rapid hand-eye coordination even when the output is settled somewhere else (e.g. in the upper central console).

**Pattern No. 14**
*Advance Warning Systems*
This pattern is about reducing perceived distraction when performing secondary tasks while driving by directing the drivers attention towards the warning system early and by overlying other sources of distraction. The attention of drivers is often directed through In-Vehicle Information Systems. Warning systems should help for directing the attention towards a probably dangerous situation but are often not recognized due to other sources of distraction.

**Pattern No. 15**
*Control of Technology used by Kids in the Rear Seat*
This pattern is about reducing distraction caused by kids in the rear seat by controlling the use of technology in the rear seat.
Activities on the rear seat can be noisy and very disturbing for the driver. Disturbance can either be caused by the interactive technology (speaker sound) or the unintended use of in-car technology (e.g.; electric window). While in other contexts, parents will restrict the use of disturbing technology, the control parents have over the rear seat is limited because they are physically distant and concerned with a driving task.

**Pattern No. 16**
*Letter Input with Eyes on the Road*
This pattern is about reducing distraction caused by interacting with an IVIS system while driving through input of letters by gesture.
Users are typing letters or numbers on their IVIS system during trips, which takes their eyes off the road and distracts them from the main driving tasks. Tasks, which have a low demand outside of the vehicle, like typing-in a road name, become challenging when the text input task has to be conducted while driving.

**Pattern No. 17**
*Menu Depth and Number of Options*
This pattern is about reducing distraction caused by navigating visual menus as a secondary task.
While driving, navigation of in-vehicle user interface menus causes distraction. Given the safety implications of visual distraction, it is important to minimize visual demand of these menus.

**Pattern No. 18**
*Display Touch Field Size*
This pattern is about determining the optimal touch screen target size. Navigating in-vehicle displays while driving causes distraction, leading to road deviations and possibly to crashes. Thus, visual demand of touch screen menus has to be minimized while preserving maximum usability.

**Pattern No. 19**
*Auditory Information and Warnings*
This pattern is about designing auditory information and warnings that are quick to capture and easy to comprehend.
When using only visual warnings, driver distraction can occur. Still, drowsiness and inattentiveness increase the risk of traffic accidents. Thus it is still necessary to direct the drivers attention to potential dangers by different means.

**Pattern No. 20**
*Choosing the Best Modality for Warning Displays*
This pattern is about choosing the right warning display modality for different situations, combining different modalities if adequate.
IVIS information needs to be delivered effectively while minimizing the interference with driving.

**Pattern No. 21**
*IVIS System Response Times*
This Pattern addresses the role of system response time while operating in-vehicle information systems by touch interfaces or hardware keys and its influence on driver distraction and comfort. While getting more and more complex, many modern in-vehicle information systems possess significant delays when using them because of the sheer amount of information that they have to process. The influence of system response time - the delay of a systems response after user input until it is ready to take new commands - has been discussed as a potential source of driver distraction and annoyance.

**Pattern No. 22**
*In-Vehicle Display Icon Size*
This pattern addresses recommended IVIS icon sizes.
IVIS displays transport various information, some of which require quick and accurate recognition. However, as in-vehicle displays have to convey more and more information, available space on in-vehicle displays becomes sparse.

**Pattern No. 23**
*Visual Display Color Choices*
This pattern is about choosing adequate colors for visual displays.
IVIS displays transport various information, some of which require quick and accurate recognition. However, as in-vehicle displays have to convey more and more information, they still need to be processed quickly.

**Pattern No. 24**
*Physical Buttons Versus Touch Screen Interfaces*
This pattern addresses the question whether touch screens or physical buttons should be used.
Current touch-screen devices provide no tactile feedback concerning control orientation, location and separation from one another. While driving, they cannot be operated with eyes on the road, which in turn leads to long off-road glances. NHTSA guidelines suggest that touch interfaces should not be operated while driving. On the other hand, touch screen devices provide much more flexibility, which is needed to operate modern, feature-rich in-vehicle information systems.

**Pattern No. 25**
*Reducing Distraction caused by IVIS Feedback*
This pattern addresses the question whether or not to display IVIS information.
Every additional information given by an in-vehicle information system can lead to driver distraction. Thus, feedback on cruise control, semi-autonomous driving, etc. may result in information overload, thus distracting the driver.

**Pattern No. 26**
*Button Feedback Times and Modalities*
This pattern addresses the design of buttons and touch fields, relating to feedback.
With the increased number of functions in a car, more and more controls are needed. Thus, it is tempting to equip in-vehicle information systems with large amounts of buttons that might also have multiple functions. To the driver, this can be frustrating and even distracting.

**Pattern No. 27**
*The Right Placement of Significant Items on In-Vehicle Displays*
This pattern addresses the question where to place important pieces of information on an In-Vehicle Display.
While paying attention to the road, every distraction of the driver yields potential for causing dangerous situations. Thus, while acquiring information visually from the In-Vehicle Display, the right placement of information is of significant importance.

**Pattern No. 28**
*Optimal Brightness of Illuminated Icons*
This pattern addresses the problem of choosing the right brightness for in vehicle light sources (e.g. buttons, information signals, a.s.o.) without reducing the driver's visual perception at night. The interior of a modern car is packed with a lot of functions, buttons and features. In most of these cases these are highlighted during day and night to assure visibility, especially in darker environment. While it is a good idea to highlight important items in the car, attention should be paid to the brightness level of the light source, as a too bright light source can distract the driver or even restrict night vision abilities.

**Pattern No. 29**
*Size of Push Buttons*
This pattern is aiming to answer the common questions about form factors of push buttons and switches used as control units in in-vehicle interior.
Choosing the right push buttons and switches for different vehicle features is not an easy task. Size and pressure sensitivity are only two of many variables that need to be considered when designing the control units in the interior of a car. While any button could do the work - optimized solutions can improve the usability as well as the interior overall quality.

**Pattern No. 30**
*Rotary Controls - Rotation Direction*
Rotating clockwise or counter-clockwise to zoom-in? To increase performance and reduce human error rates resulting from a mismatch between the operators expectations and the relationship between the display and controls, a standardized solution has to be introduced.
While navigating through e.g. urban areas the driver has to be accustomed with the control mechanisms of the system to use it without running into usability problems. Navigation systems from manufacturers albeit using rotary controls do not have the same rotation direction for certain tasks. Using the Audi MMI Navigation Software, to zoom-in the user has to rotate clockwise, while the BMW i-Drive Navigation System requires counter-clockwise rotation for the same task.

**Pattern No. 31**
*Touchscreen Buttons*
Nowadays in-vehicle information systems are equipped with touchscreens which make it easier to operate within the car. This pattern addresses user interface related design questions, focusing on displayed touchable buttons and similar objects in general.
There is no general standard on how to display touchable icons, buttons a.s.o. in a graphical user interface using a touchscreen display. Therefore it is highly recommended to use state of the art visualizations of touch based control interfaces, to guarantee barrier free interaction with high usability and joy of use.

**Pattern No. 32**
*Finding the Right Display Size*
This pattern addresses the problem of choosing the right display size for in-car infotainment and navigation systems.
Embedded in-car navigation and infotainment systems are almost state of the art in newer cars. Nevertheless there is no unifying standard for in-vehicle display sizes. This pattern proposes the ideal display size for in-car navigation and infotainment systems mostly placed in the upper part of the middle console.

**Pattern No. 33**
*Tactile Feedback on In-Vehicle Information System Touchscreens*
Auditory and visual feedback are state of the art feedback methods for in-vehicle touchscreen interaction systems. Recent studies have shown, that adding tactile feedback can reduce driver distraction even more. Diver distraction should be avoided. As this is almost impossible while interacting with touchscreen displays in modern in-vehicle information displays, driver distraction should be reduced to a minimum.

**Pattern No. 34**
*Friction of Rotary Controls*
Rotary control interfaces are present in almost all newer vehicles (e.g. BMW iDrive control knob). They are great control units for indirect interaction with in-vehicle information systems. This pattern addresses the optimal friction / haptic feedback for rotary controls to improve the joy of use.
Using rotary controls as an indirect input device without haptic feedback may create dangerous situations as the drivers tend to search for visual feedback on the control panel or display.

**Pattern No. 35**
*Ideal Loudness of Verbal & Acoustic Warning Signals*
Auditory warnings are more and more common in modern vehicles. Especially CAS are increasing in numbers. Warnings are usually played from the car speaker system and range from beeping sounds to verbal warnings. When implementing such features there is always the question how loud these acoustic warnings should be. While being acoustically warned in the car, the main aim is to get the drivers attention in a specific danger situation. The acoustical warning should only be interpreted in one way, without annoying the driver. Therefore the right loudness is a significant factor.

**Pattern No. 36**
*Maintaining & Increasing Trust (Vehicle Context)*
This pattern gives a general overview of trust in the automotive context. Trust in technology is an important topic, especially in vehicles. Gaining trust in e.g. assistance systems is essential for drivers relying on them on a daily basis, as trust in and reliance on such systems can improve joy of use and overall safety. ABS for instance are pretty much built-in in almost every newer car. When built-in, drivers have to trust these assistance systems without the need to put him-/herself and possibly others into dangerous situations (e.g. test the system in order to gain trust in them). This kind of “testing" via exposing oneself to hazardous situations would be contradictory to the purpose of assistance systems, as these systems aim to reduce the risk of accidents or similar situations. This pattern present possible approaches in order to increase, raise and maintain trust.

**Pattern No. 37**
*Gesture Controls in In-Vehicle Information Systems: State of the Art Implementations*
Gesture Control is making its way into the car. More and more car manufacturers are installing this new innovative way of interaction possibilities in their cars. This pattern shows recent studies and state of the art approaches and implementations of gesture controlled in-vehicle information systems. Finding an interaction method without the necessity of direct haptic interaction and not limited by noise factors.

**Pattern No. 38**
*Interaction Possibilities for Co-Drivers*
This pattern addresses the question whether the co-driver should have interaction possibilities in the car interior e.g. for driver - co-driver collaboration. Although limited, co-drivers have access to car interior features and input options. What are the appropriate functions the co-driver should have access to, without being distracted too much and avoiding e.g. motion sickness as well as too much mental workload?
Interaction with in-vehicle functions during driving may increase drivers distraction. Should there be low priority functions which are still in the interaction radius of the driver but as well aimed for co-driver interaction, helping to reduce drivers mental workload and improve driver - co-driver collaboration?

**Pattern No. 39**
*Button/Function States in Graphical User Interfaces*
This pattern deals with the graphical representation of function states of buttons and functions. As the IVIS should appear visually attractive and invite users to interact with them. Therefore it is necessary to provide an appealing and consistent graphical user interface with appropriate visual feedback for buttons and function states. If the user actuates a function through touch based input, direct feedback is necessary to tell the user that the system is working or the state has changed. Usually this is done with a change in the appearance to provide visual feedback. To amplify the effect it is possible to add additional audio or tactile feedback. As the visual effect is not always defined precisely, there is room for interpretation and creativity which, aside from benefits, can cause problems creating a consistent graphical environment. Thus there is a need to know how the visual change has to be in order to provide suitable feedback.

**Pattern No. 40**
*Instrument Cluster Lighting*
This Pattern tries to answer the problem of choosing the right brightness of instrumental clusters in the dashboard (e.g., warning lights).
Custom made instrument clusters may provide additional valuable and important information about the vehicles state. Therefore readability hast to be guaranteed during day, twilight and night conditions.

**Pattern No. 41**
*Valid Colors for In-Vehicle Instrument Panels*
This pattern addresses the problem of choosing the right color for In-Vehicle Instrument Panels (e.g. warning signals).
In terms of color, automotive interior lighting applications are not as strictly regulated by government as are signal lighting applications. But due to existing regulations it is beneficial to know the required specifications when implementing instrument cluster applications.

**Pattern No. 42**
*Positioning of Head Up Displays*
This pattern recommends the ideal position of an HUD8 without causing distracting to the driver.
HUD's project an image on the windscreen or a separate little transparent surface mounted above the instrument cluster, to enable access to information without changing the usual viewpoint. During the driving task the view is usually fixated on the road, to be exact above the dashboard or steering wheel. Where to project the HUD to benefit the driver without distracting him too much?

**Pattern No. 43**
*LCD Display Brightness*
This Pattern gives an answer to the question - What is the right LCD display brightness for in-vehicle usage (for example IVIS systems)?
LCD displays should be readable during day as well as night conditions. While the brightness should be dimmed at night to decrease drivers distraction it should nonetheless still be bright enough to offer good readability. In contrary to nighttime conditions, during the day a much brighter illumination is necessary to provide similar readability.

**Pattern No. 44**
*A Workplace in the Car - Possibilities for Co-Drivers*
The focus in this pattern is to show some concepts and implementation examples for turning the co-drivers seat into a working place.
How can the mostly unused co-driver area be utilized as a productive working space? Due to absent scientific research there is no precise answer available - thus it is inevitable to focus on concepts and visions.

**Pattern No. 45**
*Tactile (Touch) Display Technologies - State of the Art*
This pattern intends to show the state of the art of tactile display technologies which may (with certain limitations in mind) be used in IVIS.
There are number of ways to provide tactile/haptic feedback from displays, but not all are well known. Therefore this pattern offers an overview of tactile display feedback technologies.

**Pattern No. 46**
*"Night Mode" User Interface for Reduced Eye Strain*
This pattern addresses the following question: How to handle brightness, contrast and color problems of IVIS User Interfaces at night to provide less driver distraction and improve the joy of use? Driving in twilight and night conditions may be very exhausting, as the sight is limited compared to daylight conditions. Additionally if using the IVIS and its functions (e.g. navigation), looking into a display is necessary. Depending on the display brightness, this may be either comfortable or disturbing.

**Pattern No. 47**
*Design of Auditory Warning Signals*
Auditory warning signals can alert a driver to notifications, dangerous or potential dangerous conditions and should be irrespective of head position and direction of gaze. They reduce the need to scan for displays and increase the reaction speed which the driver reacts to certain conditions. This Pattern shows how auditory warning signals should be designed. In contrast to medical equipment where warning sounds are standardized in e.g. ISO/IEC 60601-1-8, there is no general standard for in-vehicle auditory alerts. Thus it is inevitable to look into the theory of sound perception in order to construct reliable and valid auditory warning signals for vehicles.

**Pattern No. 48**
*Frequency Analysis & Examples of Auditory Warning Signals*
This pattern offers a variety of warning sounds cues used in current automotive vehicles with graphical representation, frequencies and listening samples. Designing warning sounds may prove difficult, when no reference is given. Even though Pattern: Design of Auditory Warning Signals can help sound engineers to construct warning signals, it only covers the outline and some theory. Without hints or examples, going from theory to practice may prove very difficult, as there are many variables to keep in mind while designing warning signals.

**Pattern No. 49**
*Warning Sounds - Where should the Sound come from?*
Where should warning sounds come from? Either from the rear, from the front or from the one side only? This pattern answers the following questions to provide information helping to construct robust and effective auditory warning system for vehicles.
Warning sounds are used to draw drivers (visual) attention to a certain problem or danger. But how can sound location be used to reinforce the warning itself?

**Pattern No. 50**
*Multifunction Steering Wheel Buttons – Appropriate Amount and Placement*
This pattern will provide an overview of state of the art implementations of Steering Wheel Remote Controls and, furthermore, give recommendations for button placement and the amount of buttons needed.
Modern cars offer various ways of interaction possibilities. Usually there are a lot of options to access or operate functions of an IVIS. More and more functions can be accessed with remote control buttons on the steering wheel. Nevertheless there is no standardization regarding placement and amount of buttons appropriate for steering wheel remotes.