We adapt terminology from game design to haptic feedback, defining haptic embellishments (HEs) and juicy haptics, and provide the first evidence that vibrotactile feedback can improve measures of player experience (through the PXI scale).
Juicy Haptics
Juiciness is a concept in game design that is widely defined as "excessive positive feedback." Although juiciness is usually discussed in the context of game design, we believe it is also a useful concept for designing feedback in other interactive media such as animations or movies. Thus, we define juicy haptics as:
Excessive positive haptic feedback with the intention of improving user experience in games and other interactive media.
Because “haptic feedback” can serve highly diverse interaction goals (e.g., to provide, notify, or guide) and roles (e.g., complementary, reinforcing, initial, primary, secondary) we focused on purely decorative haptic feedback. We define haptic embellishments (HEs) as:
Haptic feedback that reinforces information that is already provided through other means.
Proposed Principles of Haptic Embellishments
Designing haptic feedback is a challenging task for novice hapticians [46], in part because of the scarcity of practical guidelines on haptic design. To this end, we assembled ten principles for designing HEs in multisensory experiences through iterative brainstorming and a literature review.
We conducted a study to understand user preferences for imple-mentations of each of our ten design principles, including possible multimodal confounds and interaction effects between visual and haptic embellishments.
We found high haptic embellishment (versus low haptic embellishment) enhanced visual stimuli in four of the six visuo-haptic principles: an ticipation, staging, follow-through, exaggeration (see Figure 5a). In the four haptic-only principles (see Figure 5b), 1) haptic embellishments and visual embellishments should be synchronized exactly, 2) haptic feedback should be used to communicate an object’s energy levels (e.g., motion), and 3) vibrotactile embellishments should vary across both intensity and sharpness for different objects and events (i.e., expressivity).
Measured Effect on Player Experience
To measure added-value, we conducted a within-participants user study: 38 participants played six versions of a Breakout game - one for each combination of haptic juice (none, low, high) vs. visual juice (low, high) - in randomized order and filled out questionnaires on player experience, haptic experience, and enjoyability after each game.
We found that the presence of vibrotactile feedback, whether the "low juicy" or "high juicy" version, improved measures of player experience.
Study 2’s mean ratings of haptic feedback on enjoyability, PXI, and HX constructs. Error bars show the 95% confidence interval. We find significant differences between the “no haptics” condition and any of the juicy haptic conditions, but we do not observe difference between low and high juicy, except in HX expressivity.
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