Gesture Ambiguity in Touch Interfaces

Challenges like the “fat finger” problem emerge as touch interfaces move beyond simple taps and swipes to more complex gestures.

Have you ever ended up zooming into a picture on your phone when you meant to scroll down? Or maybe you swiped right when you meant to delete something? These frustrating situations are examples of gesture ambiguity, a growing challenge as touch interfaces become more complex. In this post, we'll explore what gesture ambiguity is, why it happens, and how designers, product managers & developers can handle it to create a smoother user experience.

Gesture ambiguity happens when a touch interface interprets the same gesture in different ways depending on the context. This can lead to errors, confusion, and a decline in the overall user experience. 

One key factor in understanding and addressing gesture ambiguity is the concept of affordances. Affordances refer to the perceived and actual properties of an object that determine how it can be used ¹. In the context of touch interfaces, affordances play a crucial role in shaping user expectations and guiding their interactions. Clear affordances can reduce ambiguity by providing visual cues that indicate the possible actions and their outcomes. For example, a button that appears raised and changes color when touched clearly affords being pressed.

Causes of Gesture Ambiguity

Several factors contribute to gesture ambiguity:

• The "Fat Finger" Problem: If touch targets are too small or close together, it can be difficult to select the correct one with your fingertip, especially on smaller screens. This is often referred to as the "fat finger" problem, and it can lead to unintended actions and gesture ambiguity.
• Overlapping Gesture Definitions: Different apps, or even different parts of the same app, might use the same gesture for different functions.
• Lack of Contextual Awareness: The user interface might not correctly interpret your intent based on what you're doing at that moment, like which tool you're using or what you have selected.
• User Variability: People perform gestures differently. Some are fast, some are slow, and the amount of pressure used can vary. This makes it hard for the system to always recognize what you meant to do.
• Physical Limitations: Users with shorter extremities or other physical limitations may have difficulty performing certain gestures accurately, further increasing the risk of ambiguity.
• Missed Accessibility Considerations: App has not accounted for accessibility considerations such as using high contrast colors for users with colorblindness, which can hinder the user from picking the correct target.
• Form factor issues: The app may not have been optimized for the different device form factors of the app’s users.

Examples

Imagine you're using a photo editing app. You want to zoom in on the picture, so you use a two-finger pinch. But instead of zooming, the app resizes the object you accidentally had your fingers over. This is a classic example of gesture ambiguity. Another common example occurs in web browsers, where a swipe might scroll down the page or take you back to the previous page, depending on where you start the swipe and which direction you swipe in. Even something as simple as a two-finger gesture can be ambiguous. For example, in some applications, it might zoom in or out, while in others, it might rotate an object.

Prevention

Teams can use several strategies to minimize gesture ambiguity:

• Consistent Gesture Language: Use the same gestures for the same functions throughout the interface, and ideally, across different applications.
• Contextual Disambiguation: Give users visual or haptic feedback to help them understand which gestures work in a particular situation and what will happen when they use them.
• Gesture Customization: Let users personalize gestures to fit their own preferences and habits.
• Clear Visual Feedback: Show users what the system thinks they did right away.
• User Testing: Test the interface with real users to identify and address potential ambiguity issues early in the design process. This can help ensure that the chosen gestures are intuitive and easy to understand for the target audience.
• Optimized for different device form factors
• Ensure Accessibility in UX Design

Methods for Handling Gesture Ambiguity

Even with the best prevention strategies, ambiguity can still happen. Here's how interfaces can handle those situations:

• Gesture Confirmation: For actions that can't be easily undone, ask the user to confirm their intention before doing something that might be ambiguous. Consider this especially for actions that are irreversible such as deletion of an entry.
• Undo/Redo Functionality: Make sure users can easily undo or redo actions if they make a mistake because of gesture ambiguity.
• Alternative Input Methods: Give users other ways to do the same thing, like using menus or voice commands.
• Mediation: When the system is unsure about which action the user intended, a mediator can be used to resolve the ambiguity. This mediator can use information from the application and the user's recent interactions to make the best decision.
• User research: Understand the behaviour of different users by observing how they use the app and incorporate the feedback into the UX design.

Conclusion and Future Outlook

Gesture ambiguity is a challenge in designing touch interfaces, especially as they become more complex. Devs, designers, PMs should account for this when they create modern, user-friendly experiences. However, there's a tension between making gestures intuitive and preventing ambiguity. As interfaces become more sophisticated, the gestures we use might need to become less like real-world actions to avoid confusion.

Looking ahead, emerging technologies like artificial intelligence and more advanced gesture recognition could help reduce ambiguity. AI could learn user preferences and context to better interpret their intentions, while improved sensors and algorithms could more accurately distinguish between similar gestures. By combining thoughtful design with these advancements, we can create touch interfaces that are both powerful and intuitive.

About the Author:
Swaroop Chand is Chief Business Officer at Niti AI, since September 2024. Based in Bengaluru, India, Swaroop brings over two decades of experience in fintech, software engineering and business growth. A graduate of the National Institute of Technology Karnataka with a B.E. in Metallurgy and Materials Science, Swaroop has held key roles at companies like Citigroup (1999-2005) and Oracle (2005-2016), before starting his own venture Lemonop. As CEO of Lemonop, he scaled a gig economy marketplace to over 850 companies before its acqui-hire by Perfios. At Perfios he led Account Aggregator, Embedded Finance and Wealth Tech Initiatives (2021-2024). Swaroop is passionate about scalable solutions, product strategy, and leveraging technology to transform industries.