# Design and Evaluation of Pseudo-Haptic Techniques for Simulating Surface Stickiness in VR

Yutaro Hirao, Céleste Bourse, Koki Hori, Takuji Narumi, Ferran Argelaguet, Anatole Lécuyer

► To cite this version:

Yutaro Hirao, Céleste Bourse, Koki Hori, Takuji Narumi, Ferran Argelaguet, et al. Design and Evaluation of Pseudo-Haptic Techniques for Simulating Surface Stickiness in VR. ISMAR 2025 - IEEE International Symposium on Mixed and Augmented Reality, Oct 2025, Daejeon, South Korea. pp.1009-1019, 10.1109/ISMAR67309.2025.00108. hal-05413105

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Submitted on 12 Dec 2025

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<figure><img src="image_1.png" /></figure>
# Design and Evaluation of Pseudo-Haptic Techniques for Simulating Surface Stickiness in VR

Yutaro Hirao*

Céleste Bourse

Koki Hori

Nara Institute of Science and Technology

ENS Rennes

Nara Institute of Science and Technology

Takuji Narumi

Ferran Argelaguet

Anatole Lécuyer

The University of Tokyo

Univ. Rennes, Inria, IRISA, CNRS

Univ. Rennes, Inria, IRISA, CNRS

## ABSTRACT

Pseudo-haptics alters vision to evoke haptic perception without dedicated hardware. We introduce a method that reproduces sticky-surface interactions during attaching-detaching 3D direct manipulation in VR by blending three cues—motion gain, surface-deformation, and vibration—in various combinations. Accurately sensing how strongly a surface “clings” is vital for realistic grasping, adhesion training and material evaluation, yet it has been largely overlooked in pseudo-haptic research. Three studies evaluated these cues. The first experiment compared individual and combined cues on perceived stickiness, confirming that additional cues reliably strengthened perceived stickiness. The second experiment tested how cue number affects tolerance for visual–physical mismatch, indicating that they lowered the minimum detectable threshold though they did not widen the overall tolerated mismatch. The third experiment measured whether and how much added cues sharpen perceptual resolution, showing multiple cues improved perceptual resolution by reducing just noticeable differences by 44% (1.8x finer), doubling discriminable levels from roughly eight with a single cue to sixteen with all cues.

**Index Terms:** pseudo-haptics, stickiness, pseudo-haptic cues

## 1 INTRODUCTION

Virtual reality (VR) technology—which renders non-existent objects/things to appear “as if they were truly there”—has been the subject of extensive research. However, a general-purpose solution for delivering haptic feedback, such as perception of weight, hardness, or stickiness during interactions with virtual objects, has yet to be established. Conventional haptic research has largely focused on physically reproducing force feedback using mechanical devices such as wire-based systems, robotic arms, and motors (e.g., [41, 27, 13]). While effective to a degree, these approaches often involve trade-offs between the intensity of the feedback and factors such as device complexity, weight, and the user’s range of motion—thereby limiting their practicality for widespread use.

To address this challenge, pseudo-haptic techniques, which leverage the integration of sensory information during cognitive processing, have gained increasing attention since the early 2000s [25]. These techniques enable the modulation of haptic perception by appropriately altering sensory feedback—such as visual or auditory cues—in response to a user’s physical actions. For instance, when the movement of a virtual object is rendered smaller than the user’s actual motion, the object can be perceived as “heavier” [43]. A key advantage of this approach is that it allows for the alteration of haptic perception without the need for complex physical haptic devices, relying instead on carefully designed sensory integration. A wide range of pseudo-haptic techniques have

been proposed, covering many fundamental haptic properties of objects [19], including weight, compliance, friction, and roughness [45]. However, to the best of our knowledge, no prior work has investigated pseudo-haptic techniques capable of simulating a sticky surface during attaching and detaching interactions—despite the fact that such interactions are common in everyday experiences involving materials like adhesive tape and viscous liquids such as honey, or glue. The central challenge therefore is to establish psychophysically grounded design guidelines that specify how multiple pseudo-haptic cues should be orchestrated to maximize both the usable range and the perceptual resolution of stickiness in such 3D attaching-detaching interactions. In response, this paper introduces and evaluates a novel pseudo-haptic method for simulating sticky surface in attaching-detaching interactions within VR environments. To design this technique, we systematically examined several pseudo-haptic cues that may contribute to the perception of stickiness—namely, motion gain, surface deformation, vibration, and their combinations.

A secondary objective of this study is to investigate the effectiveness of using multiple pseudo-haptic cues on perceptual outcomes. While it may seem intuitive that increasing the number of pseudo-haptic cues enhances the overall effect by providing richer sensory input, a closer examination of the underlying mechanisms of pseudo-haptic perception supports this expectation with theoretical grounding. One of the most widely accepted explanations for the mechanism of sensory integration is the maximum likelihood estimation model [8, 9]. According to this theory, sensory information from different modalities is integrated based on its relative reliability (or likelihood) in order to produce more accurate estimates of physical environments. Given that bottom-up sensory integration processes typically result in combined estimates with lower variance than those derived from individual sensory cues, it can be expected that incorporating multiple pseudo-haptic cues would enhance perceptual reliability and thus strengthen the pseudo-haptic experience—compared to relying on a single cue alone.

Most research on pseudo-haptics has focused on modulating a visual motion cue. However, visual motion is not the only modality capable of inducing pseudo-haptic perceptions. Previous studies have explored the use of additional cues, including changes in skin color combined with surface deformation [35], avatar posture alongside visual motion [17], and audiovisual representations of physiological signals [15]. These studies suggest that incorporating multiple sensory cues can offer greater flexibility in adjusting pseudo-haptic perceptions compared to relying on a single cue. Nevertheless, the extent to which multiple pseudo-haptic cues specifically enhance the perceived haptic experience remains largely unexplored. Moreover, it is still unclear which combinations of cues are most effective for inducing specific pseudo-haptic perceptions. To address this gap, the present study investigates the impact of incorporating additional pseudo-haptic cues—such as surface deformation and vibration—alongside visual motion. Specifically, we examine how these combinations affect both the range and resolution of pseudo-haptic perception. Through these

<footnote>*e-mail: yutarohirao@gmail.com</footnote>
experiments, we aim to propose an effective design framework for pseudo-haptic techniques capable of conveying sticky perceptions in VR.

The main contributions of the paper are as follows:

* This paper proposes a novel pseudo-haptics technique for simulating a sticky surface during attaching-detaching interactions.

* This paper proposes the design of multiple pseudo-haptic cues and systematically evaluates their effectiveness—both individually and in combination—by investigating the extent to which they enhance the range and resolution of pseudo-sticky perception.

# 2 RELATED WORK

## 2.1 Haptic Devices for Sticky Interaction

Sticky tactile feedback has traditionally been achieved by actively modulating fingertip friction with dedicated hardware. The earliest demonstrations used electroadhesion (electrovibration): Strong & Troxel showed that an AC-driven electrode matrix under a thin insulator could produce a texture effect [42], a principle later refined in TeslaTouch to add pixel-level, millisecond-latency friction cues to touchscreens without any moving parts [5]. A complementary solid-state strategy is ultrasonic friction modulation. Watanabe & Fukui discovered that vibrating a rigid plate at an ultrasonic frequency (e.g., 30 kHz) creates a squeeze-film of air that dramatically reduces friction [48]; the T-PaD display and subsequent commercial prototypes exploited this effect to present virtual ridges and edges on smooth glass [49]. Because both techniques act on the entire finger-surface contact, their spatial resolution is limited and they can only raise (electroadhesion) or lower (ultrasonic) friction, not both.

To overcome these constraints, researchers have explored wearable or hybrid mechanisms. Fingertip skin-stretch thimbles apply tangential shear of a few hundred microns, greatly amplifying perceived friction while leaving the touched object unmodified [34]. Magnetorheological-fluid cells can be magnetically stiffened, producing bidirectional friction changes and even local bumps, though its primary challenges involve ensuring long-term fluid stability and achieving complex magnetic control, rather than bulky hardware or slow response [26]. The recent Stick-Slip device takes a still lighter approach: it jets micro-droplets of fast-evaporating fluid onto the fingerpad, achieving up to ±60% changes in friction on any ordinary surface, yet introduces logistical issues such as fluid supply and droplet targeting [28].

Overall, hardware solutions deliver genuine mechanical forces but suffer from custom actuation, power consumption, and limited scalability. Pseudo-haptic techniques sidestep these drawbacks by manipulating visual or control-display mappings to cognitively evoke stickiness, requiring no special gear and thus integrating seamlessly into large-scale or multi-user AR/VR setups—the focus of the present work.

## 2.2 Pseudo-haptics Techniques

Since the introduction of pseudo-haptic techniques in 2000 [25], a wide range of methods have been developed to simulate various haptic properties. According to Jones and Lederman [19], haptic properties of objects can be broadly categorized into two types: material properties and geometric properties. Numerous pseudo-haptic techniques have been proposed to modulate these properties. Material properties include texture—such as roughness and friction [33]—with examples including [30, 47, 11, 24]; compliance [25, 35, 40, 22, 44]; and weight [43, 38, 39]. Geometric properties, on the other hand, encompass curvature [2], orientation and angle [21, 1, 2, 12], and size [3]. Furthermore, research in retargeting and redirection [21, 37] can be also regarded as part of the pseudo-haptics domain, as geometric properties are often interpreted as

haptic properties. These studies highlight that modifying perceived haptic properties through multisensory integration—primarily visual and haptic—is a core aspect of pseudo-haptic techniques [36].

Among the wide range of studies on pseudo-haptic techniques, some have specifically aimed to simulate sticky perception. For example, Costes et al. proposed a method for inducing pseudo-sticky perception during touchscreen tracing by modifying the shape and motion of on-screen UI elements [7]. Similarly, Ujitoko et al. introduced a technique for presenting pseudo-static-friction by visually simulating stick-slip transitions using a cursor during interactions involving a surface and a touch pen [47]. In addition to these, several related studies have explored the simulation of surface friction or viscosity. However, the majority of these works have focused on 2D touchscreen-based interactions. To date, no research has addressed the simulation of sticky sensations during direct touch and detachment in virtual reality (VR) environments. Therefore, to the best of our knowledge, this study is the first to propose a pseudo-haptic technique for simulating sticky surfaces specifically during touch and detachment interactions in VR.

A secondary objective of this paper is to investigate the effectiveness of combining multiple pseudo-haptic cues to enhance the pseudo-haptics. One of the key limitations of current pseudo-haptic techniques lies in their relatively narrow range of haptic expressiveness. Psychophysical studies have quantified the extent to which these techniques can modulate different haptic perceptions. For instance, pseudo-haptics can alter the perception of weight by approximately 3–5% [43, 39], compliance by 20–35% [23, 44], friction by 23% [47], and fine roughness by around 5% [46]. In related fields such as retargeting and redirection, it has been shown that hand motion perception can be altered by up to 13.75% in the forward direction and 6.18% in the backward direction without users noticing the manipulation [50]. These findings suggest that while pseudo-haptic techniques can indeed modify perception—typically in the range of 5% to 35%, depending on the specific haptic properties—they still fall short when compared to the dynamic range achievable with physical haptic devices. This limitation poses a challenge for broader, more practical applications in VR environments. Some prior studies have attempted to overcome this issue by enhancing the realism of avatars [32] or by introducing "haptic noise" to the user's body [14, 31]. However, even these approaches have yielded only modest improvements—for example, the range of perceptual modulation was extended by merely 13% in one study using the noise-based approach [15]. To address this challenge, this paper aims to provide a more detailed examination of the potential benefits of combining multiple pseudo-haptic cues.

## 2.3 Investigating Multiple Pseudo-haptic Cues

Several studies have examined pseudo-haptics by comparing the effects of individual pseudo-haptic cues and their combinations on haptic perception. Ban and Ujitoko addressed visual/physical discrepancy issues by introducing a visual string metaphor that connects a user's finger and the cursor on a touchscreen [4]. While their technique proved effective for touchscreens, its application to VR interaction requires further investigation since users cannot see their physical hands in VR environments. Punpongsanon et al. implemented two visual effects for pseudo-softness in augmented reality (AR) based on the force applied to a surface: the surface deformation effect (SDE), which visualizes physical deformation, and the body appearance effect (BAE), which alters skin color [35]. Their experimental results confirmed that combining these two visual effects generated enhanced pseudo-haptic compliance (softness) compared to using SDE alone. Similarly, Jauregui et al. investigated three visual effects for pseudo-weight perception on displays: modifications to spatial mapping between user gestures and avatars, variations in animation motion profiles, and changes in avatar posture (upper-body inclination) [17]. Their find-
ings indicated that combining these visual effects led to improved pseudo-weight discrimination. Hirao and Kawai combined motion gain with visualizations of physiological responses—including skin color changes representing applied force, hand tremor, and heartbeat sound feedback [15]. Their results suggest that audiovisual representations of physiological responses during interaction can enhance pseudo-haptics and potentially mitigate negative impacts on interaction realism. These studies collectively suggest that multiple pseudo-haptic cues can enhance the overall pseudo-haptic experience. However, no research has thoroughly investigated the extent to which this additive strategy specifically expands the range of pseudo-haptic perception (especially with visual cues). To address these gaps, this paper examines how multiple pseudo-haptic cues affect the range and resolution of pseudo-haptic perception, with a particular focus on pseudo-sticky perception, by comparing motion cues, surface deformation cues, and vibration cues.

## 3 NOVEL PSEUDO-HAPTIC TECHNIQUES FOR SURFACE STICKINESS IN VR

<figure><img src="image_2.png" /><figcaption>Figure 1: The figure illustrates our novel pseudo-haptic techniques designed to induce sticky perception. (a) motion gain, (b) breaking height, (c) surface deformation, and (d) vibration.</figcaption></figure>

We designed four distinct techniques to simulate sticky surface interactions in VR: three visual cues (visual motion gain, visual surface deformation, and breaking height) and one haptic cue (controller vibration). Figure 1 illustrates these parameters.

### 3.1 Breaking Height

The breaking height represents the critical threshold at which all pseudo-haptic effects terminate. When the user's physical hand (tracked via the VR controller) reaches this height, several simultaneous events occur: the virtual hand instantly realigns with the controller position, continuous vibration ceases, a one-shot detachment vibration occurs, and surface deformation returns to its undeformed state. This parameter creates the moment of "breaking free" from the sticky surface, similar to how a sticky material suddenly releases after its limit. Through pilot testing, we found that breaking height influences the perception of surface stickiness and also affects how other parameters contribute to the overall sticky perception. This parameter forms the foundation of our approach, defining when the sticky effect transitions from resistance to release.

### 3.2 Visual Motion Gain

Visual motion gain creates a discrepancy between physical hand movement and virtual hand movement from the moment of surface contact until the breaking height is reached. This technique is well-established in the pseudo-haptics literature and has been successfully employed to simulate various force-based perceptions, including resistance, friction, and weight [45]. The virtual hand tracks the VR controller with this motion gain applied. Equation 1 describes the control law, where V represents the virtual hand position, C denotes the contact point between the virtual fingertip and sticky surface, P indicates the physical hand position (controller's position), and gain specifies the motion gain coefficient.

$$V = C + (P - C) \cdot gain \quad (1)$$

A gain of 1 causes the virtual hand to precisely match physical hand movement, while a gain of 0 creates a "stuck" effect where the virtual hand remains fixed at the contact point until the physical hand reaches breaking height. Intermediate values (such as 0.5) create partial following behavior where the virtual hand moves, but at a reduced rate compared to the physical hand.

### 3.3 Visual Surface Deformation

<figure><img src="image_3.png" /><figcaption>Figure 2: Surface deformation rendered from Eq. (2) with $\sigma = 10$ (cm) and $A = 10, 20, 30, 40$ (cm). Axes are in centimeters and share a common color scale; larger A yields a taller deformation.</figcaption></figure>

This technique visually deforms the sticky surface at the point of contact, creating a tentlike or stretching appearance that provides a visual explanation for the resistance felt during interaction. The deformation is implemented using a Gaussian function centered at the contact point, with the amplitude corresponding to the current distance between the initial finger contact point and virtual fingertip position. The mathematical implementation is defined by:

$$z(x, z) = A \cdot \exp \left( - \frac{(x - x_0)^2 + (z - z_0)^2}{2 \cdot \sigma^2} \right) \quad (2)$$

where $(x_0, z_0)$ is the contact point on the surface, $(x, z)$ is the evaluation point on the surface, A is the amplitude of the deformation defined as the distance between the finger contact point and the
current virtual fingertip position, and $\sigma = 10$ is the standard deviation chosen so that the deformation visually decays within a 30 cm radius. Figure 2 provides a visualization of Eq. 2. This technique provides crucial visual feedback that complements the kinesthetic discrepancy, creating a more coherent multi-sensory experience of stickiness.

## 3.4 Vibration Feedback

Adding to the visual-based techniques above, we also implemented vibration feedback through the controller to enhance the sticky perception. Our approach uses two distinct vibration patterns. First, a continuous low-intensity vibration (10% of maximum controller vibration) is applied from initial contact until breaking height is reached, simulating the persistent resistance of a sticky surface. Second, a one-shot maximum-intensity vibration is triggered at the moment of detachment, creating a haptic "snap" perception that reinforces the breaking free moment. This simple haptic feedback complements the visual techniques to create a more compelling multi-sensory experience of stickiness.

For the parameter design, We informally piloted several intensity pairs with five people including authors. The feedback was split into (i) a continuous buzz that signals drag while attached and (ii) a one-shot pulse on detachment. The most convincing feel came from a full-strength pulse combined with a subtle 10% continuous buzz—strong enough to notice, yet still distinct from the pulse. A full factorial study of vibration levels is future work, but including it here would have made the design unmanageably large, so we fixed vibration to this single setting.

## 3.5 Novel Elements

Our technique introduces three novel elements to pseudo-haptics. First, we add a breaking-height trigger that synchronises virtual-hand realignment, termination of the drag vibration, a one-shot "snap," and a rapid surface-relaxation reproducing the abrupt release felt when real adhesive finally lets go. Second, we contribute an adhesive surface-deformation cue: instead of the stiffness-style indents used in prior work, the surface stretches upward with the fingertip during pull-out and relaxes instantly on detachment, visually conveying stickiness throughout an attaching-detaching motion. Finally, by orchestrating this new deformation with motion gain and vibration, we deliver the first psychophysical design guidelines for strong, coherent sticky feedback in 3D interactions.

# 4 XP1: CONTRIBUTION OF EACH CUE AND COMBINATION TO PSEUDO-STICKINESS

The primary aim of our initial experiment was to examine how individual cues and their various combinations contribute to the perception of pseudo-stickiness. Specifically, we sought to address a key research question:

[RQ1-1] Does increasing the number of pseudo-haptic cues progressively enhance the perception of stickiness?

We note that all experiments described in this paper received approval from the local ethics committee.

## 4.1 Apparatus

Figure 3 presents the experimental apparatus and virtual environment setup. Participants completed the experiment while seated, equipped with an HTC Vive Pro 2 VR headset and holding a VR controller in their right hand. Within the virtual environment, participants faced a table upon which a plane with pseudo-sticky properties was positioned directly in front of them at waist height. The virtual hand, which tracked the movement of the right VR controller, maintained a fixed posture as depicted in the figure, with the index finger extended toward the plane.

<figure><img src="image_4.png" /></figure>

Figure 3: The Figure depicts the (a) experimental apparatus and (b) virtual environment setup. The blue sheet indicates the sticky material that responds differently to participant interaction based on experimental conditions. Throughout the experiment, participants can only view a virtual representation of their hand (shown as opaque in the figure) and cannot see their actual physical hand position (illustrated as translucent).

## 4.2 Condition

For the experiment, we created 10 distinct combinations of the techniques described in Section 3. We set the breaking height to a fixed value of 40 cm for all conditions. Based on pilot test results, we found that while modifying the breaking height can influence users' perception of surface stickiness, it also affects how other parameters impact pseudo-stickiness. To avoid complicating the interpretation of results in this initial investigation, we selected a standard 40 cm height—determined through pilot testing to be neither too high nor too low in a point of task load.

For visual motion gain, we tested three values: 1 (no gain, full following), 0.15 (partial following), and 0 (stuck, no movement). In addition to the two extreme parameters (gain of 1 and 0), we included a gain of 0.15. In Experiment 1 our goal was to provide the strongest, clearest pseudo-haptic cues available for each modality. For motion gain, a value of 0 would yield the maximal stickiness illusion, but it also might break visual coherence and prevents from showing surface deformation. We therefore needed a non-zero gain that still produced a vivid pull-back perception while keeping deformation visible. Pilot testing with four people including authors showed that 0.15 met these requirements, thus we adopted it.

For both surface deformation and vibration, we tested conditions with and without these features enabled. While the radius of the surface deformation and vibration intensity could potentially serve as a parameter of pseudo-stickiness, we maintained consistent intensity values to avoid an explosion in the number of experimental conditions.

Based on these parameters, we tested 10 distinct combinations in total (excluding redundant conditions such as combinations with gain of 0, where the effects of with/without visual deformation and with/without vibration would be equivalent). While these conditions do not allow for detailed analysis of each parameter's specific effects, they provide valuable initial insights into which cues and combinations effectively contribute to the perception of pseudo-stickiness.

## 4.3 Task

Participants were instructed to move their right hand to touch the virtual plane with the tip of their virtual index finger. Subsequently, they were asked to lift their hand vertically until it detached from the plane, simulating the action of freeing a stuck hand from an ad-
adhesive surface. After completing this procedure twice, participants responded to a question presented on a floating panel within the virtual environment using a 7-point Likert scale. Responses were recorded by having participants touch corresponding buttons on the panel with their virtual hand. Following response validation, a new surface with different sticky properties appeared, and participants repeated the entire procedure. Conditions were presented in randomized order, with participants completing 6 repetitions of each condition, resulting in a total of 60 experimental trials per participant.

## 4.4 Collected Data

Participant responses were recorded using a 7-point Likert scale. The specific question presented was "I felt like I touched a sticky surface," with response options ranging from 1 (strongly disagree) to 7 (strongly agree).

## 4.5 Procedure

Twenty participants (thirteen men and seven women, aged 19-31 years) were recruited for this experiment. Initially, participants received a comprehensive explanation of the study objectives, methods, and procedures. After providing informed consent, participants were fitted with the necessary equipment and received detailed instructions regarding the experimental task. Participants were instructed to hold the right controller in a manner that allowed their physical hand position to align with the virtual hand. They then proceeded to complete the experimental trials, with the option to take breaks at their discretion throughout the session. Upon completion of all trials, participants removed the equipment and took a rest period before proceeding to the second experiment. One note is that no participant took excessive breaks—and thus we consider any impact on the results negligible.

## 4.6 Hypotheses

Based on previous research on pseudo-haptics, we formulated the following hypotheses for this experiment:

[H1-1] Each pseudo-haptic cue would elicit higher stickiness ratings compared to the no-cue condition.

[H1-2] Increasing the number of combined cues would progressively enhance the perception of stickiness.

## 4.7 Results

Figure 4 presents participants' responses to the question "I felt like I touched a sticky surface." The condition labels from left to right represent: a condition with gain of 1, without deformation, and without vibration (NoCue); a condition with gain of 0.15, without deformation, and without vibration (Gain); a condition with gain of 0, without deformation, and without vibration (Stuck); a condition with gain of 1, with deformation, and without vibration (Deform); a condition with gain of 1, without deformation, and with vibration (Vibration); followed by various combinations of these parameters. For each participant, the median value of their six responses for each repeated condition was calculated as the representative value for that condition. Statistical analysis was then conducted using the Wilcoxon signed rank test with Holm correction applied for multiple comparisons. The corresponding statistical results are presented in Figure 5.

## 4.8 Discussion

### 4.8.1 All Cues Generate Sticky perception

[H1-1] was supported. Our results reveal that when comparing each individual cue condition to the NoCue baseline, all single cues

<figure><img src="image_5.png" /><figcaption>Figure 4: The figure presents the participants' reported sense of stickiness measured on a 7-point Likert scale. The boxplots display the median values along with the 25th and 75th percentiles; error bars indicate the minimum and maximum values.</figcaption></figure>

<table><caption>Figure 5: The figure displays the statistical results from the Wilcoxon Signed rank test with Holm correction applied to the sense of stickiness data (Figure 4). Each cell value represents the corresponding p-value with Holm correction lower than 0.05 for the comparison between conditions, while cells labeled "n.s." indicate Holm-corrected p-values greater than 0.05.</caption><thead><tr><th></th><th>NoCue</th><th>Gain</th><th>Stuck</th><th>Deform</th><th>Vibration</th><th>Deform+Gain</th><th>Vibration+Gain</th><th>Vibration+Stuck</th><th>Vibration+Deform</th></tr></thead><tbody><tr><td>Gain</td><td>&lt;0.001</td><td>-</td><td>-</td><td>-</td><td>-</td><td>-</td><td>-</td><td>-</td><td>-</td></tr><tr><td>Stuck</td><td>&lt;0.001</td><td>n.s.</td><td>-</td><td>-</td><td>-</td><td>-</td><td>-</td><td>-</td><td>-</td></tr><tr><td>Deform</td><td>&lt;0.001</td><td>n.s.</td><td>n.s.</td><td>-</td><td>-</td><td>-</td><td>-</td><td>-</td><td>-</td></tr><tr><td>Vibration</td><td>&lt;0.001</td><td>0.001</td><td>0.033</td><td>n.s.</td><td>-</td><td>-</td><td>-</td><td>-</td><td>-</td></tr><tr><td>Deform+Gain</td><td>&lt;0.001</td><td>&lt;0.001</td><td>&lt;0.001</td><td>&lt;0.001</td><td>&lt;0.001</td><td>-</td><td>-</td><td>-</td><td>-</td></tr><tr><td>Vibration+Gain</td><td>&lt;0.001</td><td>0.017</td><td>0.013</td><td>0.005</td><td>&lt;0.001</td><td>n.s.</td><td>-</td><td>-</td><td>-</td></tr><tr><td>Vibration+Stuck</td><td>&lt;0.001</td><td>n.s.</td><td>n.s.</td><td>n.s.</td><td>&lt;0.001</td><td>0.031127</td><td>n.s.</td><td>-</td><td>-</td></tr><tr><td>Vibration+Deform</td><td>&lt;0.001</td><td>n.s.</td><td>n.s.</td><td>0.003</td><td>&lt;0.001</td><td>n.s.</td><td>n.s.</td><td>n.s.</td><td>-</td></tr><tr><td>Vibration+Deform+Gain</td><td>&lt;0.001</td><td>&lt;0.001</td><td>&lt;0.001</td><td>&lt;0.001</td><td>&lt;0.001</td><td>0.031</td><td>0.001</td><td>&lt;0.001</td><td>0.009</td></tr></tbody></table>

(Gain, Stuck, Deform, and Vibration) demonstrated significant effects, indicating that each cue was independently capable of generating pseudo-sticky perception.

Our statistical analysis indicated that vibration alone produced significantly weaker sticky perception compared to motion gain (both Gain and Stuck conditions). These observations are consistent with previous research by Jauregui et al. [17], which similarly found that visual cues related to object motion were highly effective in facilitating pseudo-weight perception discrimination. However, we must approach these single-cue comparisons with appropriate caution. The effectiveness of individual cues may be highly dependent on their specific parameter settings. Different vibration intensities, motion gain values, or surface deformation radius might yield substantially different results. Therefore, our hierarchy of cue effectiveness should be considered specific to the parameters used in this study rather than as a universal finding. Future work could extend this investigation by systematically varying multiple parameters for each cue type, enabling more rigorous cross-cue comparisons and establishing a more comprehensive understanding of their relative effectiveness across different settings.

### 4.8.2 More Cues Produce Stronger Perception

[H1-2] was supported. Our analysis demonstrated that combinations of two cues generally produced stronger sticky perception than single cues. For example, Deform+Gain and Vibration+Gain conditions showed significantly higher ratings than individual cue conditions. Furthermore, the Vibration+Stuck combinations
nation produced significantly higher stickiness ratings than Vibration alone, and the Vibration+Deform combination yielded significantly higher ratings than both Vibration and Deform when used individually. Importantly, the combination of all three cues (Vibration+Deform+Gain) produced the strongest sticky perception overall, significantly exceeding all other conditions. These findings, demonstrating both the enhanced effectiveness of multi-cue combinations and the hierarchical differences between specific combinations, strongly support our hypothesis that multiple pseudo-haptic cues generally produce stronger perceptual effects than fewer cues.

While some comparisons involve combinations that don't include the specific single cue being compared (e.g., Vibration vs. Deform+Gain), we can draw particularly strong conclusions from those comparisons where a multiple-cue condition contains the single cue being compared (e.g., Vibration vs. Vibration+Gain). In most such cases, the multiple-cue conditions consistently and significantly outperformed their single-cue components, providing robust evidence for the enhanced effectiveness of combined pseudo-haptic cues.

## 5 XP2: EFFECT OF HAVING MULTIPLE CUES ON THE RANGE OF APPLICABLE VISUAL/PHYSICAL DISCREPANCIES

The second experiment was conducted immediately following the first experiment with the same participants. While pseudo-haptic feedback relies on visual/physical discrepancy, excessive discrepancy can either fail to generate the intended perception or create feelings of incoherence. Our objective was to determine whether multiple pseudo-haptic cues could effectively expand this usable range of discrepancy. Specifically, we aimed to identify both the lower threshold (below which users cannot perceive pseudo-stickiness) and the upper threshold (above which users perceive the interaction as incoherent or lose their sense of control). This experiment addressed two key research questions:

[RQ2-1] Do multiple pseudo-haptic cues extend the applicable range of visual/physical discrepancy compared to single cues?

[RQ2-2] What are the specific lower and upper thresholds for visual/physical discrepancies when using different cue combinations?

The apparatus was the same as in Experiment 1, except that participants now also held a left-hand controller—used solely for responding to questions in VR—while the right-hand controller remained dedicated to performing the interaction task.

### 5.1 Condition

In this experiment, two conditions were tested. The first condition, labeled "stuck," employed a motion gain of 0, which was identical to the "Stuck" condition from the first experiment. This meant that after touching the surface, the virtual hand remained completely immobile until the user lifted their physical hand above the breaking height. Once this threshold was exceeded, the virtual hand instantly jumped to match the position of the tracker, resuming normal tracking of the user's hand movements.

The second condition, labeled "moving," was identical to the "Deformation+Gain" condition from the first experiment. It combined a motion gain of 0.15 with surface deformation. After the virtual fingertip contacted the surface, the virtual hand followed the physical hand at the reduced gain rate while the surface visibly deformed. When the user lifted their hand above the breaking height, the deformation ceased and the virtual hand returned to the tracker position, as in the "stuck" condition.

For this experiment, we conceptualized the "stuck" condition as representing a single-cue approach and the "moving" condition (Deform+Gain) as representing a multiple-cue approach. Our selection of these two specific conditions was guided by several methodological considerations. From the four cues examined in Experiment 1, we excluded vibration. For this more detailed investigation into the effects of multiple cues, we chose to focus our initial investigation on unimodal (purely visual) cues, as this approach more closely aligns with conventional pseudo-haptic techniques. This left us with Deform+Gain as the only viable multiple-cue condition. For the comparable single-cue condition, we needed to select among gain, stuck, and deform options. Since our research objective was to determine whether multiple cues could expand the acceptable range of visual/physical discrepancy in pseudo-haptic interactions, we eliminated the deform condition because it does not inherently create such discrepancy. This narrowed our options to stuck and gain conditions. We ultimately selected the stuck condition over the gain condition because the latter would have introduced an additional confounding factor: participants might perceive the interaction as unnatural due to the visible gap between the surface and the virtual fingertip due to no deformation of the surface. This spatial incongruity could potentially generate feelings of unnaturalness independent of the visual/physical discrepancy we aimed to measure.

It is important to note that visual/physical motion discrepancy is widely acknowledged as the key contributing factor to pseudo-haptic effects [36]. While gain 0 and gain 0.15 represent different parameter values that might initially seem to complicate direct comparisons between single-cue and multiple-cue conditions, focusing our analysis on the measured visual/physical discrepancy rather than the gain values themselves allows for valid comparisons. Our specific analytical approach for this comparison will be detailed in Section 5.3. Considering these factors, the stuck condition proved most appropriate as a single cue condition for our experimental focus on identifying thresholds for visual/physical discrepancy.

### 5.2 Task

In this experiment, we employed a staircase method to determine two critical breaking height thresholds: (1) the minimum height required to perceive pseudo-stickiness and (2) the maximum height beyond which the interaction begins to feel unrealistic. These thresholds collectively define the range of applicable visual/physical discrepancy.

The staircase procedure implemented adjustable breaking heights ranging from 0 to 20 cm for the minimum threshold experiment and from 30 to 50 cm for the maximum threshold experiment. These values were selected from our pilot test. For each threshold determination, we utilized two complementary series: an ascending series starting at the minimum height within the respective range and a descending series starting at the maximum height. These series were presented in alternating order.

Participants performed the same basic task as in the first experiment—touching and detaching from the sticky surface twice. The initial breaking height was set at either 0 or 20 cm for the minimum threshold experiment and either 30 or 50 cm for the maximum threshold experiment. After each interaction, participants responded to a question presented on a virtual floating panel: "Do you feel the surface is sticky?" for the minimum threshold experiment or "Do you feel the surface is too sticky?" for the maximum threshold experiment. Responses were registered using the left controller, with participants selecting "Yes" or "No" via left or right button presses, respectively. The subsequent breaking height was adjusted based on the participant's response. In the minimum threshold experiment, the breaking height decreased by one step (2 cm) toward 0 cm following a "Yes" response and increased by one step toward 20 cm following a "No" response. Conversely, in the maximum
threshold experiment, the breaking height decreased by one step toward 30 cm following a "Yes" response and increased by one step toward 50 cm following a "No" response.

The procedure continued until five turning points were recorded for each series. A turning point occurred when a participant gave a response different from their previous response in the same series. Importantly, the breaking height was constrained to remain within the initial range; when a response would have pushed the height beyond these boundaries, the height remained at the boundary value, and a turning point was recorded. This approach, with the specific number of turning points, was determined through pilot testing to minimize participant arm fatigue. Each participant completed this procedure for both experimental conditions.

## 5.3 Collected Data

The breaking height at each turning point was recorded as measurement data. For the minimum threshold determination, the question "Do you feel the surface is sticky?" was designed to identify the precise boundary below which participants perceived no stickiness but above which they began to detect the sticky sensation.

For the maximum threshold determination, the question "Do you feel the surface is too sticky?" was used. Prior to the experiment, participants received explicit instructions that "too sticky" referred to situations in which the visual-haptic discrepancies became so strong that the visual-haptic correspondence broke, movement felt unnaturally impeded, and their overall sense of immersion or agency began to degrade. Thus, these turning points aimed to capture the critical threshold above which the pseudo-haptic effect began to disrupt the interaction experience, but below which it remained perceptually effective and convincing [36, 38].

It is important to note that while the breaking height thresholds measured in this experiment represent the distance from the table to the user's hand (as shown in Figure 1), our analysis focuses specifically on the visual/physical discrepancy—the spatial offset between the virtual hand and the user's actual hand. Therefore, we converted the breaking height thresholds into visual/physical discrepancy values before conducting our analysis. For the moving condition, since the virtual hand follows the user's hand with a gain of 0.15, we calculated the discrepancy value as 0.85 times the breaking height threshold. For the stuck condition, the breaking height is identical to the discrepancy value, so no conversion was necessary.

## 5.4 Procedure

Following the completion of the first experiment and after sufficient rest periods, participants proceeded to the second experiment. They were equipped with the VR headset and instructed to hold a VR controller in each hand. Participants then performed the previously described tasks, with the option to take breaks at their discretion throughout the experimental session. One note is that no participant took excessive breaks—and thus we consider any impact on the results negligible.

## 5.5 Hypotheses

For this experiment, we hypothesized that:

[H2-1] The multiple-cue condition would provide a wider range of applicable visual/physical discrepancy than the single-cue condition.

Additionally, a key objective of this experiment was to identify the specific minimum and maximum threshold values for each condition.

<figure><img src="image_6.png" /><figcaption>Figure 6: The figures present the average visual/physical discrepancy thresholds across conditions (cm). The left figure displays the low thresholds, while the right one shows the high thresholds. Error bars represent standard error of the mean.</figcaption></figure>

## 5.6 Results

As described in Section 5.3, we first multiplied the obtained data for the Moving condition by 0.85 to convert breaking heights to visual/physical discrepancy values. Figure 6 presents the average visual/physical discrepancy thresholds determined from the five turning points for each condition.

For the high threshold, the Stuck condition yielded an average value of 34.48 ± 1.24 cm (*mean* ± *standard error*) and the Moving condition produced a threshold of 33.10 ± 1.00 cm. For the low threshold, the Stuck condition resulted in an average value of 7.84 ± 1.20 cm, compared to the Moving condition's 3.23 ± 0.60 cm. These values indicate that the range of applicable visual/physical discrepancies—calculated as the difference between high and low thresholds—was 26.64 cm in the Stuck condition and 29.87 cm in the Moving condition.

Statistical analysis using paired t-tests revealed a significant difference between conditions for the low threshold ($t(19) = 2.78, p = 0.012, d = 1.01$), but no significant difference for the high threshold ($t(19) = 1.38, p = 0.183, d = -0.24$). Further analysis of the range between high and low thresholds showed no statistically significant difference between conditions ($t(19) = -1.46, p = 0.161, d = 0.40$).

## 5.7 Discussion: Multiple Cues Lower the Minimum Threshold for Pseudo-Stickiness Despite Similar Ranges

Our hypothesis [H2-1] was partially supported by the experimental data. The threshold analysis shows that while the overall range of applicable visual/physical discrepancy was not significantly different between conditions, the multiple-cue condition (Moving) significantly lowered the minimum threshold at which participants could perceive stickiness compared to the single-cue condition (Stuck). Specifically, participants could detect sticky perception at a much lower discrepancy value (3.23 cm) with multiple cues than with a single cue (7.84 cm). This finding suggests that the additional pseudo-haptic cue of surface deformation enhances sensitivity to subtle sticky effects. The visual representation of elasticity through deformation appears to provide supplementary perceptual information that helps users detect minimal resistance, creating a more coherent experience even with smaller visual/physical offsets.

We must acknowledge an alternative factor that might influence these results: the fundamental difference in visual feedback between conditions. In the Moving condition, participants observed continuous virtual hand movement post-contact, while the Stuck condition provided no such visual feedback. This absence of visual response during physical hand movement might contribute to the observed threshold differences. However, our focus on vi-
sual/physical discrepancy rather than raw gain values allows for meaningful comparisons between these conditions. Despite their different visual presentations, both conditions create quantifiable discrepancies between physical and virtual hand positions that can be directly compared. Furthermore, findings from the first experiment demonstrated that participants effectively interpreted both techniques as valid methods for inducing pseudo-sticky perception. Given that all participants completed the first experiment prior to the second, they had already developed a conceptual understanding of both sticky sensation methods. Future research should expand on these findings by investigating whether this enhanced sensitivity at lower thresholds extends to additional pseudo-haptic cue combinations and exploring how different types of visual feedback might influence perceptual thresholds.

# 6 XP3: EFFECT OF HAVING MULTIPLE CUES ON THE RESOLUTION OF PSEUDO-STICKINESS

The objective of the third experiment was to investigate how multiple pseudo-haptic cues affect the resolution of pseudo-sticky perception. Specifically, we aimed to determine the minimum difference in breaking height that would induce perceptibly different levels of sticky sensation. This experiment addressed two key research questions:

[RQ3-1] Do multiple pseudo-haptic cues improve the resolution of perceived stickiness?

[RQ3-2] What is the minimum breaking height difference needed to perceive distinct stickiness levels?

The same apparatus used in the second experiment was employed for this experiment. We investigated the same two conditions as in the second experiment: the Stuck condition (single cue) and the Moving condition (multiple cues).

## 6.1 Task

The experiment employed the method of constant stimuli to determine the just noticeable difference (JND) in breaking height required to perceive different levels of stickiness. Each condition was investigated separately. Participants were tasked with comparing the sticky perception between two virtual surfaces: a reference surface and a comparison surface. Both surfaces utilized the same pseudo-haptic cue condition (either both Stuck or both Moving). The reference surface consistently had a breaking height of 20 cm, while the comparison surface had one of six possible breaking heights: 15.2 cm, 16.8 cm, 18.4 cm, 21.6 cm, 23.2 cm, or 24.8 cm (corresponding to ±8%, ±16%, and ±24% variations from the reference). For each trial, participants first touched and detached from the initial surface twice. After this surface disappeared, a second surface appeared in the same position following a 1-second delay. Participants then performed the same touching and detaching task twice with this second surface. Subsequently, a question panel appeared, asking "Which surface did you feel stickier?" with response options "the former" or "the latter." Participants provided their responses using the left VR controller. Each comparison was repeated 12 times, resulting in a total of 144 trials per participant (6(comparisonheights * 12iterations * 2cueconditions).

## 6.2 Collected Data

Each participant's response was recorded to calculate the JND in sticky perception. As in the second experiment, the data obtained from the moving condition was multiplied by 0.85 to convert breaking heights to visual/physical discrepancy values, ensuring our analysis focused on the actual discrepancy between virtual and physical hand positions.

<figure><img src="image_7.png" /><figcaption>Figure 7: The figure presents the psychometric curves derived from each participant responses. The curves plot the average percentage of trials in which participants judged the comparison surface to be stickier than the reference surface (20 cm breaking height), as a function of comparison surface breaking height.</figcaption></figure>

## 6.3 Procedure

Ten participants (eight men and two women, aged 22-24 years) took part in the experiment. The general procedure followed the same protocol as the first and second experiments, including initial instructions, consent form completion, equipment setup, and practice trials. Upon completion of all experimental trials, participants received compensation in the form of a 1000 yen Amazon gift card.

## 6.4 Hypothesis

The hypothesis for this experiment was formulated as follows:

[H3-1] The JND of the Moving condition is smaller than that of the Stuck condition.

We proposed this hypothesis based on the expectation that the Moving condition, which incorporated multiple pseudo-haptic cues compared to the single cue in the Stuck condition, would enable finer discrimination of sticky perception, thereby increasing the resolution of pseudo-sticky perception.

## 6.5 Results

The data were analyzed using Probit analysis [10] to calculate parameters of the best-fitting cumulative normal function for each participant. JND values for each pseudo-sticky cue condition were determined as half the distance between the 25% and 75% points on the psychometric curve for each participant. Since these values represent JNDs in terms of breaking height, we converted them to visual/physical discrepancy values, consistent with our analytical approach in previous experiments. For the moving condition, this conversion involved multiplying the breaking height JND by 0.85. This analysis yielded JND values of 3.4 ± 0.47 cm for the Stuck condition and 1.9 ± 0.17 cm for the Moving condition. A paired t-test revealed a significant difference between the JNDs of the two conditions ($t(9) = 2.7, p = 0.02, d = 1.3$). Figure 7 displays the psychometric curves calculated from each participant's responses.

# 6.6 Discussion: Multiple Cues Significantly Improve Stickiness Discrimination Sensitivity

[H3-1] was supported by our experimental results. The condition employing multiple pseudo-haptic cues (the Moving condition, which combined motion gain and surface deformation) demonstrated a 44% smaller JND compared to the condition with only
a motion gain cue (the Stuck condition). This finding indicates that multiple pseudo-haptic cues significantly enhance the discrimination of different levels of stickiness.

It is important to note that the JND was investigated with reference to a breaking height of 20 cm, and may vary if examined with different reference breaking heights. However, considering previous research on JND in pseudo-haptic perception (e.g. [40]), we believe that our conclusions regarding the enhanced discriminative capability of multiple cues would likely remain valid across different breaking heights.

# 7 GENERAL DISCUSSION

A key finding revealed that combining multiple pseudo-haptic cues significantly enhances the user experience in multiple ways: it strengthens the intensity of perceived stickiness (as demonstrated in the first experiment), lowers the minimum threshold at which users can begin to perceive stickiness (as suggested in the second experiment), and substantially improves the resolution of pseudo-sticky perception—with JND values 44% smaller or, equivalently, providing 1.8 times finer discrimination—compared to using visual motion gain alone (as indicated in the third experiment). Although the overall range of applicable visual/physical discrepancy was not significantly different between conditions, the multiple-cue condition enabled perception of stickiness at much smaller discrepancy values while also creating stronger sticky perception throughout the perceptible range. These results align with previous research [35, 17, 15], all of which demonstrated that increasing the number of pseudo-haptic cues enhances the overall effect. Based on our measurements, we can estimate that a single pseudo-haptic cue (motion gain) can effectively present approximately eight distinguishable levels of sticky perception (calculated as the applicable range divided by JND: 26.64/3.4), while multiple pseudo-haptic cues (motion gain and surface deformation) can present approximately sixteen distinguishable levels (29.87/1.9). This demonstrates that incorporating multiple pseudo-haptic cues substantially increases the granularity of presentable sticky perception, offering designers more precise control over virtual material properties.

Potential applications include VR assembly or repair training where users must handle glues or tapes; medical simulators that teach surgeons to manage tissue adhesion or remove sticky dressings; and tele-operation or cobot interfaces that let operators “feel” viscous or adhesive materials when manipulating them remotely. The technique can also offer designers a low-cost way to prototype sticky interactions such as with materials like adhesive tape and viscous liquids such as honey, or glue.

## 7.1 Can we generalize the findings for other pseudo-haptic properties?

Pseudo-haptic techniques can be classified according to the taxonomy proposed by Ujitoko et al. [45], which organizes them into combinations of three input types (displacement, pressing duration, and force) and four visual stimuli responses (displacement, surface deformation, size, and color). Techniques within the same taxonomic category likely share similar underlying perceptual mechanisms, while the specific haptic property experienced may depend on the interaction context. For example, our experimental results demonstrate that combining "displacement" input with "displacement" visual stimuli (motion gain cue) effectively induces pseudo-sticky perception. This same fundamental technique has been successfully employed to generate pseudo-weight perception in previous research (e.g., [43, 39]). This would be because the same pseudo-haptics technique is used after touching a virtual surface for pseudo-sticky perception, while it is used after lifting a virtual object for pseudo-weight perception, and this difference in context changes the attribution of the cause of the inputs and visual stimuli. While breaking height serves as a critical parameter for pseudo-

stickiness, informal participant interviews during our experiments revealed that sticky perception was often perceived before reaching the breaking height threshold.

If we assume that the perceptual mechanisms underlying pseudo-haptic effects remain consistent within a given input-stimulus combination regardless of the target haptic property, our findings regarding multiple cues likely generalize to other pseudo-haptic techniques within the same taxonomic category. This is particularly significant because techniques using displacement input with displacement visual stimuli represent the most widely implemented approach and encompass the broadest range of haptic material properties, including weight, compliance, friction, roughness, material characteristics, and various force properties [45].

Furthermore, the benefits of employing multiple pseudo-haptic cues have been corroborated by previous research examining different taxonomic combinations, such as Punpongsanon et al. [35] who combined "force" input with "surface deformation" and "color" visual stimuli, and Hirao et al. [15] who integrated "displacement" input with "displacement," "color," and auditory feedback. These studies suggest that our findings regarding enhanced perceptual range and resolution with multiple cues may extend beyond the specific taxonomic pseudo-haptics category examined in our experiments. Future research should systematically investigate the generalizability of these benefits across different pseudo-haptic techniques and taxonomic classifications.

## 7.2 Future work: does the addition of more cues always enhance pseudo-haptics?

Our results, consistent with prior studies [35, 17, 15], show that adding pseudo-haptic cues usually amplifies the targeted illusion. Yet the effect is neither linear nor always positive: too many cues can widen the gap between virtual and physical feedback [15], suggesting a quantitative ceiling that remains unexplored.

Cognitive-load theory explains this risk. Because working memory is limited, redundant signals can hinder performance [6]. Kao et al. report that excessively "juicy" interfaces—rich in visual and auditory embellishments—draw attention away from task-relevant information and degrade user experience [20]. Similar attention-diversion principles underlie pain-reduction studies that modulate sensory experience by shifting focus [18, 29, 16].

Each extra pseudo-haptic cue therefore competes for finite cognitive resources. If some cues contribute less to the illusion, they may siphon attention from the more potent ones, paradoxically weakening the overall effect. In certain cases, removing weaker cues could produce a stronger, clearer impression.

Future work should identify the point of diminishing returns by sequentially adding cues in order of effectiveness—or removing them from least to most effective—to establish design guidelines that go beyond the simplistic notion that "more cues are always better."

## 7.3 Limitations

Because our method relies on visual modulation only, we have not yet validated how closely it can reproduce the full force range of real, highly viscous adhesives. Nonetheless, within the tested parameter space we doubled the number of discriminable sticky levels over a single-cue baseline, providing the first fine-grained design space for VR stickiness. In Experiment 2 the multi-cue condition displayed continuous hand motion whereas the single-cue condition did not; analysing thresholds as visual/physical discrepancies rather than raw gains mitigated this bias and offers a template for future studies.

The evaluation used a right-hand controller with 20 participants in Experiments 1-2 and 10 in Experiment 3; broader samples, other limbs, and bimanual tasks will be examined next, along with individual factors such as VR experience or sensory sensitivity. Exper-
iment 1 relied on a single 7-point stickiness rating, whereas Exper-
iments 2-3 employed psychophysical thresholds and JNDs; forth-
coming work will add multi-dimensional scales (e.g., realism, fa-
tigue) to capture wider user experience. Because no physical ad-
hesive baseline was included, our results are relative to pseudo-
haptic conditions; a follow-up study will compare cue combinations
against real sticky materials to calibrate an absolute scale.

Finally, to keep the design tractable we fixed a 40 cm break-
ing height, a 0.15 motion gain, and one vibration profile. Mapping
the full parameter space—alternative heights, finer gains, and var-
ied vibration waveforms—and adapting them to task load remain
important goals for future research. Together, these extensions will
refine our guidelines and broaden the applicability of pseudo-haptic
stickiness in VR.

8 CONCLUSION

This paper introduces a novel pseudo-haptics technique for simu-
lating sticky surface interactions in VR environments. We designed
and evaluated multiple pseudo-haptic cues—including motion gain,
surface deformation, and vibration—to assess their effectiveness in
generating sticky perception, both individually and in combination.

Three experiments were conducted to systematically investigate different aspects of this perceptual phenomenon. The first experiment examined how individual cues and their combinations contribute to perceived stickiness. Results demonstrated that increasing the number of pseudo-haptic cues enhances the overall effect. The second experiment investigated how multiple pseudo-haptic cues affect the applicable range of visual/physical discrepancies. Results revealed that while the overall range was not significantly different between conditions, multiple cues significantly lowered the minimum threshold at which users could perceive stickiness. This allowed participants to detect sticky perception at much smaller discrepancy values when presented with multiple cues compared to a single cue. The third experiment assessed how multiple pseudo-haptic cues influence the resolution of sticky perception—specifically, the minimum breaking height difference required to perceive distinct levels of stickiness. Results showed that multiple pseudo-haptic cues reduced JND values by 44% (or provided 1.8 times finer discrimination) compared to a single cue. When considered alongside findings from the second experiment, these results suggest that multiple cues can double the number of distinguishable sticky perception, from approximately eight levels with a single cue to sixteen levels with multiple cues.

Collectively, these findings confirm the effectiveness of our approach in simulating sticky interactions in VR environments. More broadly, our research demonstrates that incorporating multiple pseudo-haptic cues can significantly enhance both the intensity and perceptual granularity of pseudo-haptic interactions.

ACKNOWLEDGMENTS

This work was partially supported by the MEXT Grant-in-Aid
for Scientific Research (S) (19H05661), Grant-in-Aid for JSPS
Fellows (21J12284), Grant-in-Aid for Research Activity Start-
up (23K20007), and Grant-in-Aid for Early-Career Scientists
(24K20818).

REFERENCES

[1] M. Azmandian, M. Hancock, H. Benko, E. Ofek, and A. D. Wilson. Haptic retargeting: Dynamic repurposing of passive haptics for enhanced virtual reality experiences. In *Proceedings of the 2016 chi conference on human factors in computing systems*, pp. 1968–1979, 2016. 2

[2] Y. Ban, T. Kajinami, T. Narumi, T. Tanikawa, and M. Hirose. Mod-
ifying an identified curved surface shape using pseudo-haptic effect.
In *2012 IEEE Haptics Symposium (HAPTICS)*, pp. 211–216. IEEE,
2012. 2

[3] Y. Ban, T. Narumi, T. Tanikawa, and M. Hirose. Modifying perceived size of a handled object through hand image deformation. *Presence: Teleoperators and Virtual Environments*, 22(3):255–270, 2013. 2

[4] Y. Ban and Y. Ujitoko. Enhancing the pseudo-haptic effect on the touch panel using the virtual string. In *2018 IEEE Haptics Symposium (HAPTICS)*, pp. 278–283. IEEE, 2018. 2

[5] O. Bau, I. Poupyrev, A. Israr, and C. Harrison. Teslatouch: electrovibration for touch surfaces. In *Proceedings of the 23rd annual ACM symposium on User interface software and technology*, pp. 283–292, 2010. 2

[6] K. Collins and B. Kapralos. Pseudo-haptics: Leveraging cross-modal perception in virtual environments. *The Senses and Society*, 14(3):313–329, 2019. 9

[7] A. Costes, F. Argelaguet, F. Danieau, P. Guillotel, and A. Lécuyer. Touchy: A visual approach for simulating haptic effects on touch-screens. *Frontiers in ICT*, 6:1, 2019. 2

[8] M. O. Ernst and M. S. Banks. Humans integrate visual and haptic information in a statistically optimal fashion. *Nature*, 415(6870):429–433, 2002. 1

[9] M. O. Ernst and H. H. Bülthoff. Merging the senses into a robust percept. *Trends in cognitive sciences*, 8(4):162–169, 2004. 1

[10] D. Finney. Probit analysis (3rd edition). 1971. 8

[11] M. Fukushima, T. Takemoto, and M. Fujimura. A study on pseudo-haptics by cursor moving with motion blur. In *2013 Seventh International Conference on Complex, Intelligent, and Software Intensive Systems*, pp. 751–754. IEEE, 2013. 2

[12] D. T. Han, M. Suhail, and E. D. Ragan. Evaluating remapped physical reach for hand interactions with passive haptics in virtual reality. *IEEE transactions on visualization and computer graphics*, 24(4):1467–1476, 2018. 2

[13] T. Hashimoto, S. Yoshida, and T. Narumi. Metamorphx: An un-
grounded 3-dof moment display that changes its physical properties
through rotational impedance control. In *Proceedings of the 35th An-
nual ACM Symposium on User Interface Software and Technology*, pp.
1–14, 2022. 1

[14] Y. Hirao, T. Amemiya, T. Narumi, F. Argelaguet, and A. Lécuyer. Leveraging tendon vibration to enhance pseudo-haptic perceptions in vr. *IEEE Transactions on Visualization and Computer Graphics*, 2023. 2

[15] Y. Hirao and T. Kawai. Augmented cross-modality: Translating the physiological responses, knowledge and impression to audio-visual information in virtual reality. *Electronic Imaging*, 31:1–8, 2018. 1, 2, 3, 9

[16] H. G. Hoffman, J. N. Doctor, D. R. Patterson, G. J. Carrougher, and T. A. Furness III. Virtual reality as an adjunctive pain control during burn wound care in adolescent patients. *Pain*, 85(1-2):305–309, 2000. 9

[17] D. A. G. Jauregui, F. Argelaguet, A.-H. Olivier, M. Marchal, F. Mülton, and A. Lecuyer. Toward” pseudo-haptic avatars”: Modifying the visual animation of self- avatar can simulate the perception of weight lifting. *IEEE transactions on visualization and computer graphics*, 20(4):654–661, 2014. 1, 2, 5, 9

[18] W. A. Johnston and V. J. Dark. Selective attention. *Annual review of psychology*, 1986. 9

[19] L. A. Jones and S. J. Lederman. *Human hand function*. Oxford university press, 2006. 1, 2

[20] D. Kao. The effects of juiciness in an action rpg. *Entertainment Computing*, 34:100359, 2020. 9

[21] L. Kohli. Redirected touching: Warping space to remap passive haptics. In *2010 IEEE Symposium on 3D User Interfaces (3DUI)*, pp. 129–130. IEEE, 2010. 2

[22] A. Kumar, R. Gourishetti, and M. Manivannan. Mechanics of pseudo-haptics with computer mouse. In *2017 IEEE International Symposium on Haptic, Audio and Visual Environments and Games (HAVE)*, pp. 1–6. IEEE, 2017. 2

[23] A. Lécuyer, J.-M. Burkhardt, S. Coquillart, and P. Coiffet. "boundary of illusion": an experiment of sensory integration with a pseudo-haptic system. In *Proceedings IEEE Virtual Reality 2001*, pp. 115–122. IEEE, 2001. 2

[24] A. Lécuyer, J.-M. Burkhardt, and L. Etienne. Feeling bumps and holes
without a haptic interface: the perception of pseudo-haptic textures. In *Proceedings of the SIGCHI conference on Human factors in computing systems*, pp. 239–246, 2004. 2

[25] A. Lécuyer, S. Coquillart, A. Kheddar, P. Richard, and P. Coiffet. Pseudo-haptic feedback: can isometric input devices simulate force feedback? In *Proceedings IEEE Virtual Reality 2000 (Cat. No. 00CB37048)*, pp. 83–90. IEEE, 2000. 1, 2

[26] C.-H. Lee and M.-G. Jang. Virtual surface characteristics of a tactile display using magneto-rheological fluids. *Sensors*, 11(3):2845–2856, 2011. 2

[27] T. H. Massie and J. K. Salisbury. The phantom haptic interface: A device for probing virtual objects. In *Proceedings of the ASME winter annual meeting, symposium on haptic interfaces for virtual environment and teleoperator systems*, vol. 55, pp. 295–300. Chicago, IL, 1994. 1

[28] A. Mazursky, J. Serfaty, and P. Lopes. Stick&slip: Altering fingerpad friction via liquid coatings. In *Proceedings of the 2024 CHI Conference on Human Factors in Computing Systems*, pp. 1–14, 2024. 2

[29] K. D. McCaul and J. M. Malott. Distraction and coping with pain. *Psychological bulletin*, 95(3):516, 1984. 9

[30] T. Narumi, Y. Ujitoko, Y. Ban, T. Tanikawa, K. Hirota, and M. Hirose. Resistive swipe: Visuo-haptic interaction during swipe gestures to scroll background images on touch interfaces. In *2017 IEEE World Haptics Conference (WHC)*, pp. 334–339. IEEE, 2017. 2

[31] M. Ogawa, K. Matsumoto, K. Aoyama, and T. Narumi. Expansion of detection thresholds for hand redirection using noisy tendon electrical stimulation. In *2023 IEEE International Symposium on Mixed and Augmented Reality (ISMAR)*, pp. 1026–1035. IEEE, 2023. 2

[32] N. Ogawa, T. Narumi, and M. Hirose. Effect of avatar appearance on detection thresholds for remapped hand movements. *IEEE Transactions on Visualization and Computer Graphics*, 27(7):3182–3197, 2020. 2

[33] S. Okamoto, H. Nagano, and Y. Yamada. Psychophysical dimensions of tactile perception of textures. *IEEE Transactions on Haptics*, 6(1):81–93, 2012. 2

[34] W. R. Provancher and N. D. Sylvester. Fingerpad skin stretch increases the perception of virtual friction. *IEEE Transactions on Haptics*, 2(4):212–223, 2009. 2

[35] P. Punpongsanon, D. Iwai, and K. Sato. Softar: Visually manipulating haptic softness perception in spatial augmented reality. *IEEE transactions on visualization and computer graphics*, 21(11):1279–1288, 2015. 1, 2, 9

[36] A. Pusch and A. Lécuyer. Pseudo-haptics: from the theoretical foundations to practical system design guidelines. In *Proceedings of the 13th international conference on multimodal interfaces*, pp. 57–64, 2011. 2, 6, 7

[37] S. Razzaque. *Redirected walking*. The University of North Carolina at Chapel Hill, 2005. 2

[38] M. Rietzler, F. Geiselhart, J. Gugenheimer, and E. Rukzio. Breaking the tracking: Enabling weight perception using perceivable tracking offsets. In *Proceedings of the 2018 CHI Conference on Human Factors in Computing Systems*, pp. 1–12, 2018. 2, 7

[39] M. Samad, E. Gatti, A. Hermes, H. Benko, and C. Parise. Pseudo-haptic weight: Changing the perceived weight of virtual objects by manipulating control-display ratio. In *Proceedings of the 2019 CHI Conference on Human Factors in Computing Systems*, pp. 1–13, 2019. 2, 9

[40] F. A. Sanz, D. A. G. Jáuregui, M. Marchal, and A. Lécuyer. Elastic images: Perceiving local elasticity of images through a novel pseudo-haptic deformation effect. *ACM Transactions on Applied Perception*, 10(3):17–1, 2013. 2, 9

[41] M. Sato. Spidar and virtual reality. In *Proceedings of the 5th Biannual World Automation Congress*, vol. 13, pp. 17–23. IEEE, 2002. 1

[42] R. M. Strong and D. E. Troxel. An electrotactile display. *IEEE transactions on man-machine systems*, 11(1):72–79, 2007. 2

[43] Y. Taima, Y. Ban, T. Narumi, T. Tanikawa, and M. Hirose. Controlling fatigue while lifting objects using pseudo-haptics in a mixed reality space. In *2014 IEEE Haptics Symposium (HAPTICS)*, pp. 175–180. IEEE, 2014. 1, 2, 9

[44] M. Tatezono, K. Sato, K. Minamizawa, H. Nii, N. Kawakami, and

S. Tachi. Effect of haptic feedback on pseudo-haptic feedback for arm display. In *2009 ICCAS-SICE*, pp. 4332–4337. IEEE, 2009. 2

[45] Y. Ujitoko and Y. Ban. Survey of pseudo-haptics: Haptic feedback design and application proposals. *IEEE Transactions on Haptics*, 14(4):699–711, 2021. 1, 3, 9

[46] Y. Ujitoko, Y. Ban, and K. Hirota. Modulating fine roughness perception of vibrotactile textured surface using pseudo-haptic effect. *IEEE Transactions on Visualization and Computer Graphics*, 25(5):1981–1990, 2019. 2

[47] Y. Ujitoko, Y. Ban, and K. Hirota. Presenting static friction sensation at stick-slip transition using pseudo-haptic effect. In *2019 IEEE World Haptics Conference (WHC)*, pp. 181–186. IEEE, 2019. 2

[48] T. Watanabe and S. Fukui. A method for controlling tactile sensation of surface roughness using ultrasonic vibration. In *Proceedings of 1995 IEEE International Conference on Robotics and Automation*, vol. 1, pp. 1134–1139. IEEE, 1995. 2

[49] L. Winfield, J. Glassmire, J. E. Colgate, and M. Peshkin. T-pad: Tactile pattern display through variable friction reduction. In *Second Joint EuroHaptics Conference and Symposium on Haptic Interfaces for Virtual Environment and Teleoperator Systems (WHC'07)*, pp. 421–426. IEEE, 2007. 2

[50] A. Zenner and A. Krüger. Estimating detection thresholds for desktop-scale hand redirection in virtual reality. In *2019 IEEE Conference on Virtual Reality and 3D User Interfaces (VR)*, pp. 47–55. IEEE, 2019. 2