%Version 3.1 December 2024
% See section 11 of the User Manual for version history
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%                                                                 %%
%% Please do not use \input{...} to include other tex files.       %%
%% Submit your LaTeX manuscript as one .tex document.              %%
%%                                                                 %%
%% All additional figures and files should be attached             %%
%% separately and not embedded in the \TeX\ document itself.       %%
%%                                                                 %%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%%\documentclass[referee,sn-basic]{sn-jnl}% referee option is meant for double line spacing

%%=======================================================%%
%% to print line numbers in the margin use lineno option %%
%%=======================================================%%

%%\documentclass[lineno,pdflatex,sn-basic]{sn-jnl}% Basic Springer Nature Reference Style/Chemistry Reference Style

%%=========================================================================================%%
%% the documentclass is set to pdflatex as default. You can delete it if not appropriate.  %%
%%=========================================================================================%%

%%\documentclass[sn-basic]{sn-jnl}% Basic Springer Nature Reference Style/Chemistry Reference Style

%%Note: the following reference styles support Namedate and Numbered referencing. By default the style follows the most common style. To switch between the options you can add or remove Numbered in the optional parenthesis. 
%%The option is available for: sn-basic.bst, sn-chicago.bst%  
 
%%\documentclass[pdflatex,sn-nature]{sn-jnl}% Style for submissions to Nature Portfolio journals
%%\documentclass[pdflatex,sn-basic]{sn-jnl}% Basic Springer Nature Reference Style/Chemistry Reference Style
\documentclass[pdflatex,sn-mathphys-num]{sn-jnl}% Math and Physical Sciences Numbered Reference Style
%%\documentclass[pdflatex,sn-mathphys-ay]{sn-jnl}% Math and Physical Sciences Author Year Reference Style
%%\documentclass[pdflatex,sn-aps]{sn-jnl}% American Physical Society (APS) Reference Style
%%\documentclass[pdflatex,sn-vancouver-num]{sn-jnl}% Vancouver Numbered Reference Style
%%\documentclass[pdflatex,sn-vancouver-ay]{sn-jnl}% Vancouver Author Year Reference Style
%%\documentclass[pdflatex,sn-apa]{sn-jnl}% APA Reference Style
%%\documentclass[pdflatex,sn-chicago]{sn-jnl}% Chicago-based Humanities Reference Style

%%%% Standard Packages
%%<additional latex packages if required can be included here>

\usepackage{graphicx}%
\usepackage{multirow}%
\usepackage{amsmath,amssymb,amsfonts}%
\usepackage{amsthm}%
\usepackage{mathrsfs}%
\usepackage[title]{appendix}%
\usepackage{xcolor}%
\usepackage{textcomp}%
\usepackage{manyfoot}%
\usepackage{booktabs}%
\usepackage{algorithm}%
\usepackage{algorithmicx}%
\usepackage{algpseudocode}%
\usepackage{listings}%
\usepackage{subcaption}
\usepackage{siunitx}
%%%%

%%%%%=============================================================================%%%%
%%%%  Remarks: This template is provided to aid authors with the preparation
%%%%  of original research articles intended for submission to journals published 
%%%%  by Springer Nature. The guidance has been prepared in partnership with 
%%%%  production teams to conform to Springer Nature technical requirements. 
%%%%  Editorial and presentation requirements differ among journal portfolios and 
%%%%  research disciplines. You may find sections in this template are irrelevant 
%%%%  to your work and are empowered to omit any such section if allowed by the 
%%%%  journal you intend to submit to. The submission guidelines and policies 
%%%%  of the journal take precedence. A detailed User Manual is available in the 
%%%%  template package for technical guidance.
%%%%%=============================================================================%%%%

%% as per the requirement new theorem styles can be included as shown below
\theoremstyle{thmstyleone}%
\newtheorem{theorem}{Theorem}%  meant for continuous numbers
%%\newtheorem{theorem}{Theorem}[section]% meant for sectionwise numbers
%% optional argument [theorem] produces theorem numbering sequence instead of independent numbers for Proposition
\newtheorem{proposition}[theorem]{Proposition}% 
%%\newtheorem{proposition}{Proposition}% to get separate numbers for theorem and proposition etc.

\theoremstyle{thmstyletwo}%
\newtheorem{example}{Example}%
\newtheorem{remark}{Remark}%

\theoremstyle{thmstylethree}%
\newtheorem{definition}{Definition}%

\raggedbottom
%%\unnumbered% uncomment this for unnumbered level heads

\begin{document}

\title[Article Title]{Subtle Cues for Navigation in Virtual Reality: How to Effectively Guide Users in VR?}

%%=============================================================%%
%% GivenName	-> \fnm{Joergen W.}
%% Particle	-> \spfx{van der} -> surname prefix
%% FamilyName	-> \sur{Ploeg}
%% Suffix	-> \sfx{IV}
%% \author*[1,2]{\fnm{Joergen W.} \spfx{van der} \sur{Ploeg} 
%%  \sfx{IV}}\email{iauthor@gmail.com}
%%=============================================================%%

\author*[1]{\fnm{Grzegorz} \sur{Zwoliński}}\email{grzegorz.zwolinski@p.lodz.pl}
\author[1]{\fnm{Agnieszka} \sur{Dubiel}}\email{agnieszka.dubiel@dokt.p.lodz.pl}
\author[1]{\fnm{Dorota} \sur{Kamińska}}\email{dorota.kaminska@p.lodz.pl}


\affil*[1]{\orgdiv{Institute of Mechatronics and Information Systems}, \orgname{Lodz University of Technology}, \orgaddress{\street{116 Zeromskiego}, \city{Lodz}, \postcode{90-924}, \country{Poland}}}



%%==================================%%
%% Sample for unstructured abstract %%
%%==================================%%

\abstract{Scene exploration in virtual reality (VR) supports spatial understanding and navigation but can be cognitively demanding without physical reference points. Subtle “micro-guidance” cues—minimalistic visual, auditory, and tactile signals—may aid navigation without breaking immersion. This study tested their effectiveness in a custom VR environment where 198 participants searched for a hidden anchor while flying over an island. Six conditions were compared: no cue, light intensity, sand vortex, spatial white noise, sonar, and haptic compass. Several cue types (light, sonar, haptic compass) significantly improved target-finding accuracy over no cue, while others showed no statistical difference. Sonar, haptic compass, and light cues also reduced task completion times, though performance varied across users. Findings suggest that certain subtle cues can enhance navigation, but effectiveness depends on modality and user perception. Results support the design of personalized, multisensory navigation aids that balance guidance with user autonomy in VR.}

%%================================%%
%% Sample for structured abstract %%
%%================================%%

% \abstract{\textbf{Purpose:} The abstract serves both as a general introduction to the topic and as a brief, non-technical summary of the main results and their implications. The abstract must not include subheadings (unless expressly permitted in the journal's Instructions to Authors), equations or citations. As a guide the abstract should not exceed 200 words. Most journals do not set a hard limit however authors are advised to check the author instructions for the journal they are submitting to.
% 
% \textbf{Methods:} The abstract serves both as a general introduction to the topic and as a brief, non-technical summary of the main results and their implications. The abstract must not include subheadings (unless expressly permitted in the journal's Instructions to Authors), equations or citations. As a guide the abstract should not exceed 200 words. Most journals do not set a hard limit however authors are advised to check the author instructions for the journal they are submitting to.
% 
% \textbf{Results:} The abstract serves both as a general introduction to the topic and as a brief, non-technical summary of the main results and their implications. The abstract must not include subheadings (unless expressly permitted in the journal's Instructions to Authors), equations or citations. As a guide the abstract should not exceed 200 words. Most journals do not set a hard limit however authors are advised to check the author instructions for the journal they are submitting to.
% 
% \textbf{Conclusion:} The abstract serves both as a general introduction to the topic and as a brief, non-technical summary of the main results and their implications. The abstract must not include subheadings (unless expressly permitted in the journal's Instructions to Authors), equations or citations. As a guide the abstract should not exceed 200 words. Most journals do not set a hard limit however authors are advised to check the author instructions for the journal they are submitting to.}

\keywords{Virtual Reality, Wayfinding, Affordance, Visual Cues, Auditory Cues, Tactile Cues, Haptic Cues.}

%%\pacs[JEL Classification]{D8, H51}

%%\pacs[MSC Classification]{35A01, 65L10, 65L12, 65L20, 65L70}

\maketitle

\section{Introduction}\label{sec1}
Every day, individuals are exposed to a vast amount of information delivered through multiple channels. This information is gathered through the senses, which operate independently or in collaboration to interpret the incoming signals. However, receiving and interpreting such signals require the individual to direct their attention to the relevant information. Attention, in this context, is defined as the process of focusing on a specific element while filtering out other stimuli from the environment \cite{pashler2016attention}. Drawing attention to a particular object elevates it to the forefront of consciousness, thereby enhancing the processing of information related to that object and improving its perception \cite{pashler2016attention}. For instance, when an individual concentrates on a specific element, they begin to notice finer details, which can alter their perception of the object compared to their initial impression \cite{itti2001computational}. This heightened focus sharpens both cognition and perception. In addition, attention plays a crucial role in situational awareness, enabling individuals to process information about their current environment more effectively and significantly reducing reaction times \cite{evans2011visual}. Attention also facilitates the integration of different sensory attributes, such as color, motion, shape, sound, and spatial location \cite{evans2011visual}. This integration is essential for the construction of coherent and perceptible representations of objects or signals within human consciousness.

It may initially appear that the process of capturing attention is entirely beyond influence, as it seems to depend solely on individual predispositions. While this perception contains some truth—after all, it is impossible to directly control how much attention someone will devote to a specific element—it is possible to design "hidden" cues that guide the recipient's focus toward a particular target chosen by the creator. Achieving this involves implementing various strategies during the design and development phases of applications, games, or films. Designers face the challenge of effectively stimulating the recipient's senses without inadvertently causing distractions. This task is demanding, as even minor details can divert the audience’s focus away from the intended goal. Research demonstrates that excessive focus or overthinking movements can hinder the execution of well-practiced skills \cite{bliss1892investigations}, \cite{boder1935influence}. For instance, Walter Schneider recounts his experience while downhill skiing. When he consciously thought about which foot was responsible for transferring his weight during a turn, his performance suffered significantly, resulting in more falls and reduced efficiency during the descent \cite{schneider1983attention}. A similar phenomenon is discussed by Gallwey \cite{gallwey2014inner}, who describes an experiment involving distraction in tennis. He suggests asking an opponent about their forehand technique during a court change. This question redirects the opponent’s attention to their actions, leading to a noticeable decline in the quality of their performance. The same effect is evident among video game players, where individuals with otherwise perfected skills experience performance declines when they overanalyze their actions. This phenomenon, known as "choking," was studied extensively by Baumeister \cite{baumeister1984choking}, who explored how social pressure and self-awareness of results negatively affect performance.

Building on the aforementioned observations, it becomes evident that achieving distraction is relatively effortless. This raises an intriguing question regarding its counterpart: does attracting and sustaining attention occur with the same ease? Empirical evidence suggests otherwise. While capturing attention is a more complex process, it is nonetheless achievable. Over the years, creators and researchers have sought optimal methods to direct recipients' attention toward specific goals (e.g., \cite{wulf1998instructions}, \cite{wulf1999learning}, \cite{mcnevin2003increasing}, \cite{shea2001advantages}). Current findings indicate that significant success can be achieved when attention is externally oriented—that is, when participants focus on the tool or external elements rather than the mechanics of their actions. For example, Wulf et al. demonstrated this principle in an experiment involving slalom skiing with a simulator \cite{wulf1998instructions}.

Another effective means of stimulating attention lies in the strategic use of lighting. For decades, filmmakers and directors have emphasized its pivotal role in visual storytelling, as well as its applications in designing three-dimensional virtual environments \cite{block2001visual}, \cite{calahan1996storytelling}, \cite{treisman1980feature}. Properly chosen lighting can evoke specific moods, enhance the visibility of key elements, and guide the viewer's focus to critical aspects of a scene \cite{calahan1996storytelling}. Insights from neuroscience and psychophysics have further elucidated lighting-related features that influence visual attention, such as contrast, symmetry, and eccentricity \cite{treisman1980feature}, \cite{itti2001modeling}. Lighting, therefore, is not only a fundamental tool in film and theater but also plays a crucial role in video games and virtual reality (VR) applications, where the structural parallels are significant.

Beyond lighting, additional modalities can be leveraged to direct attention effectively. For instance, sound cues are increasingly utilized in virtual reality applications. In VR environments, where images dynamically shift with the participant's head movements, maintaining consistent attention becomes a considerable challenge. Game designer Brian Allgeira suggests that VR participants often focus on the brightest objects within a scene \cite{bucher2017storytelling}. Furthermore, he highlights the role of "spatialized sound," which subtly guides attention toward a sound source, thereby directing the recipient's focus to elements intended by the creator \cite{watercutter2017dear}. VR presents fascinating opportunities for exploration; however, navigation and wayfinding often pose significant challenges due to the absence of gravity, the lack of a sense of temporal passage, and the scarcity of motion cues \cite{elvins1997visfiles}.

While overt navigational aids such as arrows or glowing paths have been extensively explored in traditional video games, they often prove too intrusive in immersive VR experiences. In virtual reality, maintaining a strong sense of presence is essential, and overly explicit cues can interrupt the user’s natural perception of space and agency. As noted by Boletsis \cite{boletsis2017virtual}, the use of direct visual guidance—though effective in conventional interfaces—can disrupt immersion when not carefully balanced within spatial and narrative contexts. This issue becomes particularly relevant in VR applications where the design aims to support free exploration and internalized decision-making. Consequently, designers and researchers are increasingly turning to subtle, multisensory alternatives that guide attention without dominating the perceptual field or diminishing the feeling of being present in the virtual world.

Our study focuses on such \textit{micro-guidance cues}—subtle visual, auditory, and haptic signals that gently steer the user’s attention while avoiding overt distraction and supporting a natural exploration flow (see Fig.~\ref{fig:combined_figure}). By evaluating discreet variations across these sensory modalities, we aim to understand how minimal, multisensory stimuli can support effective wayfinding while preserving the user’s sense of presence and natural exploration.

This approach aligns with a broader goal of \textit{personalizing} VR experiences without overwhelming users or imposing rigid behavioral scripts. We concentrate on three primary sensory channels—vision, hearing, and touch—as these are the most consistently measurable and widely supporte d in contemporary consumer-grade VR systems \cite{mcmahan2003tool, dede2009immersive}. Although future systems may incorporate additional modalities such as olfactory or vestibular input, our decision to limit the scope to these three senses reflects both their current practical availability and their critical role in user attention and navigation. This focus allows us to investigate the effectiveness of subtle multimodal guidance within the technical and perceptual boundaries of present-day VR.

This study involves users navigating from a drone-like perspective over an island to locate a hidden anchor using different guidance methods. The cues comprise two visual aids—a sand vortex rising above the anchor and a subtle increase in light intensity over the anchor’s location—two auditory cues: a directional white noise that intensifies as users orient toward the anchor, and a sonar frequency cue that increases in rate as the user approaches the target—and one tactile cue in the form of a haptic compass, which delivers vibration feedback based on the user's orientation, with the strongest signal occurring when facing the target and gradually decreasing as the user turns away.

Designing effective wayfinding aids in VR requires a nuanced understanding of how sensory cues influence the user’s ability to navigate and locate targets without causing unnecessary distraction. This study aims to evaluate the effectiveness and perceived subtlety of these cues, addressing the following research questions:

\begin{itemize}
    \item \textbf{RQ1:} Which type of subtle cue is most effective in assisting users in locating a target in a VR environment?
    \item \textbf{RQ2:} How do subtle guidance cues affect users’ navigation performance and perceived subtlety in VR wayfinding tasks?
\end{itemize}


The remainder of the article is structured as follows: In Sec.~\ref{sec:rel}, we briefly present the critical aspects of VR in the context of focusing the audience's attention through visual and audio signals. Then, we discuss the application created for the research, present the research group participating in the experiment, and the research procedure in~\ref{sec:method}. Results are presented in~\ref{sec:results} and concluded in~\ref{sec:conc}.

\section{Related work}
\label{sec:rel}
\subsection{Visual Cues}

One widely used technique for directing viewer attention is the spotlight metaphor, extensively employed in theater, cinema, and computer graphics applications \cite{box2020set}. In artistic contexts, the spotlight not only captures attention but also evokes specific emotional responses from the audience \cite{box2020set}. A notable implementation is its graphical use for highlighting areas of interest. For example, this effect enhances TV graphics and graphical user interfaces, such as the Mac OS X Finder. Additionally, the Boom Chameleon system \cite{tsang2002boom} incorporates the spotlight technique to emphasize regions of interest within 3D models. Advances in computer-controlled lighting and dynamic shadow manipulation have further simplified these techniques, making them more accessible to designers and end users alike \cite{barzel1997lighting}. Some studies have even treated shadows as first-class modeling primitives, facilitating their integration into user-centric designs \cite{pellacini2002user}.

Research shows that both peripheral and central visual changes can automatically orient visuospatial attention \cite{posner1980orienting}. This includes gaze direction and social cues \cite{driver1999gaze, friesen1998eyes, hietanen1999does}, as well as symbolic indicators like arrows \cite{hommel2001symbolic, ristic2002eyes}. Visual cues such as eye contact in VR, implicit lines, or explicit road signs all meet key criteria for triggering rapid attentional shifts. By leveraging these mechanisms, VR designers can create experiences that naturally capture attention and guide users seamlessly through virtual spaces.

Landmarks also play an important role. They help identify locations \cite{downs2011cognitive}, support navigation to destinations \cite{klippel2005structural}, and confirm route choices \cite{michon2001and, philbeck2005remembered}. By structuring spatial knowledge, landmarks allow users to gauge their position relative to goals more effectively \cite{couclelis1987exploring}. They also provide directional cues that indicate when to change course \cite{michon2001and}. Their usefulness has been demonstrated in studies on route learning \cite{tlauka1994effect, waller2007landmarks} and navigation decision-making \cite{golledge1999wayfinding}. It is worth noting that their effectiveness can be evaluated within virtual environments as well \cite{chen1999theoretical}.

Motion is one of the most powerful stimuli for attracting human attention. The visual system is highly sensitive to environmental changes, especially dynamic object motion. In immersive environments like VR or games, moving elements can effectively guide attention and help maintain focus on specific scene areas. Franconeri and Simons \cite{franconeri2003moving} showed that motion automatically captures attention—even when irrelevant to the task. This applies to both real and apparent motion (e.g., animations). Predictable, continuous motion supports eye tracking and sustained attention \cite{cavanagh1992attention}.

In digital environments, a moving object can act as an “attention guide,” assisting navigation or indicating task sequences. Research by Mital et al. \cite{mital2011clustering} demonstrates that in complex scenes, the eye naturally follows moving elements. This effect can be harnessed in educational VR, presentations, or games to structure content and aid understanding. As Itti and Koch \cite{itti2001computational} note, integrating motion cues into saliency models improves predictions of which elements will attract attention. Thus, motion not only boosts perceptual relevance but also supports cognitive information selection.

Subtle gaze cues in rendering and computer graphics have been utilized for years to direct the user's attention to specific parts of an image \cite{bailey2009subtle}. More recently, however, real-time gaze tracking has been used in interactive graphics applications \cite{luebke2002level, levoy1990gaze, duchowski2002breadth, o2003eye} and large-scale display systems \cite{baudisch2003focusing} to improve computational efficiency and perceived quality. These systems use real-time eye tracking to track the viewer's gaze. This phenomenon involves analyzing eye movement data in real-time, with subtle modulation of the image space, to direct the viewer's gaze to a specific scene \cite{bailey2009subtle}. With the development of computer graphics, as in 2D images \cite{mitchell2004taking}, the concept of depth of field has also been applied to 3D scenes \cite{miksch2001semantic}. DeCarlo and Santella \cite{decarlo2002stylization} took a different approach to directing the viewer's gaze - they recorded the gaze pattern of a single observer over an animation. They used it to direct the gaze of others. They achieved this phenomenon by creating a stylized rendering of the image, in which areas highlighted by the first observer are shown in great detail to subsequent participants. Similar stylized rendering techniques for guiding gaze in 3D scenes were used by Cole et al. \cite{cole2006directing}. Unlike previous approaches, which draw the viewer's eye by manipulating focus or level of detail, the subtle gaze-guiding technique employs brief modulations of luminance or warm image space presented in the peripheral areas of the visual field \cite{bailey2009subtle}.

Recent AR and VR user studies have further confirmed that subtle cues are effective for guiding exploration and navigation without overwhelming the visual scene. For example, Nonino et al.~\cite{nonino2021peripheral} demonstrated how subtle lighting, motion, and peripheral cues can influence users’ wayfinding decisions in VR. Stefanucci et al.~\cite{stefanucci2022effects} provided a framework showing that AR-style navigational aids, such as beacons and compasses, support spatial learning while preserving situational awareness in immersive tasks.

When creating visual interaction cues for VR games, it is essential to consider factors such as a consistent colour palette \cite{brandse2014using} or the placement of visual cues throughout the game \cite{totten2019architectural}. Some applications, such as games that place a strong emphasis on exploration, like Stormland, utilize visual cues to guide players through the game world \cite{rogers2014level}. These games typically consist of visually complex scenes with many interactive and non-interactive game objects that should encourage exploration. One of the main challenges for designers is the difficulty of guiding players in the right direction without compromising the application's purpose and keeping the user engaged \cite{castillo2008game}. Dillman et al. \cite{dillman2018visual} distinguish visual clues along three dimensions: task (i.e., the purpose of the clue), trigger source (i.e., the circumstances under which the clue is displayed), and selection (i.e., the visual design of the clue). In terms of the task dimension, designers use clues to support players in exploring interactive objects, gazing at the appropriate point in a game scene, or navigating to a location at a game level. For example, in VR exploration games (e.g., The Solus Project), players move a motion controller across the scenery. As soon as the controller pointer intersects an object required to continue the game, the user interface (UI) changes its appearance (e.g., the interaction icon). Similar concepts can be found in many game genres, such as action and adventure games (e.g., Alice VR), sports games (e.g., Apex Construct), or simulations (e.g., Microsoft Flight Simulator). These directions and features guide designers of video and VR games in effectively and subtly guiding the participant through the application \cite{lankes2022gazecues}.

Overall, visual cues—ranging from subtle lighting and gaze modulation to explicit landmarks and moving objects—remain a cornerstone for orienting users in immersive environments and serve as a solid foundation for combining or complementing other sensory guidance methods.

\subsection{Auditory cues}


Previous studies on wayfinding in virtual environments highlight a predominance of visually oriented aids~\cite{dodiya2008use}. However, it is essential to consider that auditory cues can effectively complement or substitute visual aids, particularly when visual stimuli are limited or overwhelming. Humans are highly responsive to temporal changes in audio signals, making sound a valuable modality for enhancing dynamic engagement and spatial awareness. Research underscores the utility of sound as an additional or alternative channel for navigation in immersive environments~\cite{dodiya2007perspectives}.

According to research by Alais and Burr~\cite{alais2004ventriloquist}, the human perceptual system integrates sensory information in a probabilistic manner, based in part on the reliability of each stimulus. In the case of auditory input, modulation of sound intensity—especially a gradual increase in volume—can signal the approach of a sound source. This, in turn, elicits heightened alertness and draws the listener’s attention to a specific spatial location. This phenomenon, known as \textit{auditory looming}, can be effectively used to guide attention toward a particular object or event~\cite{neuhoff1998perceptual}.

Additionally, as Spence and Driver~\cite{spence1996audiovisual} point out, spatialized sounds whose intensity dynamically changes with respect to the user’s position can enhance directional perception. In practice, this means that modulating sound over time in VR can help users orient themselves toward specific targets or follow a desired path. Supporting this idea, research on audio hinting~\cite{walker2005mappings} shows that users locate objects more quickly in digital environments when those objects are linked to sounds of increasing intensity. This approach has shown promise in games, educational applications, and accessibility tools for users with limited visual perception.

These perceptual principles are reflected in applied research. For instance, Dodiya et al.~\cite{dodiya2008use} introduced a navigation assistance system that employed continuous musical sounds to guide users through virtual environments. This reduced cognitive load by replacing complex visuals with intuitive auditory guidance, leading to smoother and more enjoyable navigation.

The use of 3D spatialized sound has also been evaluated in this context. Gunther et al.~\cite{gunther2004using} tested whether 3D sound could assist users in locating targets within virtual environments and enhance spatial understanding. Their findings revealed that spatial sound significantly shortened object search time in complex environments. However, it did not substantially improve spatial memory, suggesting that auditory cues primarily support immediate navigation rather than long-term spatial learning.

More recent work has explored the use of sound under sensory constraints. Fialho et al.~\cite{fialho2023soundspace} studied how sighted participants navigated VR environments blindfolded using only auditory cues. The experiment featured two phases: an initial learning trial and a recall trial, in which users navigated using auditory feedback from environmental elements. Results, correlated with neuropsychological metrics, confirmed the efficacy of sound-based navigation, particularly in supporting task execution and spatial awareness.

Auditory cues are especially significant for individuals who are blind or visually impaired~\cite{loomis2020assisting}. For example, the interactive audio mapping system presented in~\cite{loeliger2014wayfinding} enabled visually impaired users to explore and navigate digital maps using simulated 3D sound and synthetic speech. This supported route planning and fostered independent navigation. Similarly, Zhao et al.~\cite{zhao2020effectiveness} compared audio and visual feedback in wayfinding tasks using smart glasses. Although visual guidance yielded slightly better performance, users often preferred audio due to its intuitive nature and shorter learning curve.





\subsection{Tactile cues}
Tactile clues provide a hands-on approach to wayfinding, offering users physical feedback that enhances spatial awareness and movement. This form of guidance is particularly crucial for individuals with visual impairments, where tactile signals serve as essential navigational aids, enabling them to interact effectively with their environment. Consequently, the majority of research in this domain focuses on solutions tailored for blind individuals~\cite{amemiya2010orienting,kammoun2023haptisole}, while studies investigating the effects of tactile stimuli on users without visual impairments remain relatively underexplored.

For instance, Nam et al.~\cite{nam2015wayfinding} conducted a practical study examining how various environmental factors—such as the number, arrangement, and density of objects—affect task performance, perceived difficulty, and behavioral patterns of visually impaired users navigating a desktop virtual environment enhanced with haptic feedback. The findings revealed that the quantity and spatial configuration of objects significantly influenced the time and distance required to complete tasks. Moreover, object arrangement had a pronounced effect on user behavior, particularly in terms of the frequency of pauses. Additionally, perceived task difficulty varied depending on specific environmental conditions.

In efforts to improve navigation in such environments, researchers have explored ways to simulate real-world body movements within virtual spaces. One such approach was assessed by Sanchez et al.~\cite{sanchez2012videogaming}, who investigated the impact of an audio- and haptic-integrated video game called MovaWii. This game creates a virtual representation of physical space, allowing blind learners to interact through body movements and Nintendo Wii's Wiimote controllers to navigate unfamiliar environments. The results demonstrated that MovaWii effectively fosters the development of orientation and mobility skills, helping learners construct a mental map of the virtual space through its integrated audio and haptic feedback. Furthermore, participants successfully transferred navigational knowledge from the virtual world to real-world settings, enhancing their ability to move independently. While similar findings have been reported in other studies~\cite{feintuch2006low,sanchez2014audio}, these investigations predominantly focus on facilitating navigation for visually impaired users, leaving a gap in research concerning tactile wayfinding support for sighted individuals.

\begin{figure*}[h!]
  \centering
  \begin{subfigure}{0.42\linewidth}
    \centering
    \includegraphics[width=\linewidth]{training}
    \caption{Training session.}
    \label{fig:training}
  \end{subfigure}
  \hfill
  \begin{subfigure}{0.273\linewidth}
    \centering
    \includegraphics[width=\linewidth]{visual1}
    \caption{Light intensity.}
    \label{fig:visual1}
  \end{subfigure}
  \hfill
  \begin{subfigure}{0.273\linewidth}
    \centering
    \includegraphics[width=\linewidth]{visual2}
    \caption{Air movement.}
    \label{fig:visual2}
  \end{subfigure}
  \caption{Overview of the training session and visual cues used in the application.}
  \label{fig:combined_figure}
\end{figure*}


\section{Method}
\label{sec:method}
This section describes the methodology used to investigate the effectiveness of subtle multisensory cues in guiding user attention during spatial navigation tasks in a virtual reality environment. We outline the experimental design, participants, apparatus, procedure, and the specific conditions under which data were collected. 

\subsection{VR environment}
The VR application used in this study simulates a simple drone-like flight experience designed for head-mounted displays (HMDs) such as the Meta Quest 2, 3, and Pro. The decision to implement a flying locomotion system—although technically capable of full six-degree-of-freedom motion—was, in this experiment, constrained to a constant altitude of \SI{15 \pm 1}{m}     above the terrain. Locking altitude removes vertical search heuristics and keeps optic flow uniform, while free horizontal flight still eliminates ground-related confounds such as path-finding restrictions, obstacle collisions, and uneven-terrain navigation. It enables smooth, continuous movement in any direction, which simplifies the analysis of how users orient themselves and respond to subtle guidance cues. Second, aerial navigation ensures that participants maintain a consistent, unobstructed view of the environment. This elevated perspective improves the visibility and perceptibility of the visual and spatialized cues under evaluation, particularly for those designed to be minimal or peripheral. By standardizing users' field of view, the method reduces variability introduced by perspective occlusion or terrain-dependent interactions. 
Moreover, the drone-like locomotion reduces physical fatigue and avoids the pacing inconsistencies typical of walking or teleportation, which is consistent with previous findings that controller-based seated flight generally causes less strain than natural walking~\cite{9090555}. As the primary focus of this study is the assessment of attentional guidance mechanisms rather than naturalistic movement behavior, the chosen navigation model provides a neutral and immersive context for evaluating cue effectiveness across sensory modalities.

Participants interacted with the application while seated in a stationary position, without the ability to physically rotate their chairs. This design ensured user comfort and safety, reducing the risk of disorientation or simulator sickness. The application consisted of two main components: an interactive training session and the main navigation task. The training segment introduced participants to the VR environment and control scheme, allowing them to familiarize themselves with the interface by flying along a predefined red path for 60 seconds (see Fig.~\ref{fig:training}).

Navigation within the environment was achieved using the standard Meta Quest controller setup. Locomotion was implemented as a drone-like flight system, allowing free movement across the horizontal plane (X and Z axes), with altitude (Y axis) held constant. The left controller’s analog stick enabled forward, backward, and lateral movement, while the right stick controlled yaw rotation—rotating the user’s viewpoint around the vertical axis. The orientation of the virtual drone was decoupled from the participant’s head rotation, enabling free head movement within an egocentric reference frame.

To ensure comfort and reduce motion sickness, movement speed was fixed at a moderate level, with smoothed acceleration and deceleration transitions. The control scheme did not rely on controller tilt or hand orientation, avoiding unintended input and offering a simplified, accessible interface. This locomotion method supported continuous, intuitive navigation without requiring physically demanding gestures, making it appropriate for participants regardless of their prior VR experience.

After training, participants began the anchor-searching task, in which they had to locate a hidden anchor placed at a fixed position on the virtual island. All participants began the task from the same predefined starting point. This consistent setup ensured uniform spatial conditions across sessions, allowing for reliable comparison of the effectiveness of different guidance cues without introducing variability related to task layout. To support this process, the application offered six task variants, each utilizing a distinct type of subtle guidance cue. These cues were designed to engage specific sensory modalities (visual, auditory, or haptic) and assist users in finding the target while preserving immersion and minimizing cognitive load. The following cue types were tested:

\begin{enumerate}
    \item \textbf{No cue (NC)} — This condition served as the control group. The user was required to complete the task without any form of assistance. No directional or positional hints were provided, allowing for an assessment of baseline navigation performance in the absence of external stimuli.
    
    \item \textbf{Light cue (LIGHT)} — A soft, visually subtle cue in the form of increased light intensity was used to guide the user. The cue, also known as a \textit{god ray}, created a vertical column of light (aura-like effect) over the anchor’s location. The effect was integrated seamlessly into the environmental lighting system and adapted dynamically to the user's position to avoid disrupting immersion (see Fig.~\ref{fig:visual1}).

    \item \textbf{Air movement (AM)} — This condition introduced a vortex-like air motion above the anchor’s position. The effect took the form of gently rising sand particles, creating the illusion of upward air flow. This visual cue was fully integrated with the natural island environment, evoking desert-like dust devils or heat-induced turbulence. It subtly drew the user’s attention through peripheral motion without standing out as an artificial game element (see Fig.~\ref{fig:visual2}). The use of environment-consistent particles reinforced immersion while still delivering effective directional guidance.


    \item \textbf{White noise (WN)} — In this auditory cue condition, the intensity of spatialized white noise increased as the user oriented toward the target. The sound source was integrated with the VR audio system and dynamically adjusted based on head orientation. The white noise acted as a low-frequency, non-verbal directional cue, gradually intensifying as the user’s orientation aligned with the correct direction.

    \item \textbf{Sonar effect (SE)} — Inspired by echolocation principles, this condition used a sonar-like audio signal to indicate proximity to the anchor. As the user moved closer to the target, the repetition rate of the ping sound increased. The rising tempo simulated an approaching sound source, leveraging the perceptual phenomenon of auditory looming to enhance user focus and spatial precision.

    \item \textbf{Compass effect (CE)} — In this condition, the user received directional feedback solely through controller vibrations. The intensity of the haptic feedback was modulated based on the angular deviation from the anchor: vibrations were strongest when the user was facing the target and gradually weakened following a cosine function as the user's orientation deviated from the correct direction. When the user’s gaze was perpendicular to the target, the vibrations disappeared entirely. This continuous, non-visual guidance served as a subtle but effective means of indicating direction, allowing users to navigate without relying on visual or auditory channels. This design reflects established practices in haptic wayfinding systems, where increasing vibration intensity serves as positive confirmation of correct orientation rather than an error signal. Such an approach aligns with prior research on tactile compasses and navigation aids~\cite{amemiya2010orienting, kammoun2023haptisole, nam2015wayfinding, Pielot2010, vanErp2004} and supports continuous, subtle guidance without introducing negative feedback, which could disrupt immersion.

\end{enumerate}

The application records the drone's spatial and angular position in real-time, saving the data, enriched by the duration of the trial, in CSV format on the server after each attempt. This high-frequency recording (approximately 65Hz) enables a comprehensive analysis of user behavior and interactions with the VR environment. 

\subsection{Participants}
The initial pool included 218 volunteers. Based on the inclusion criteria, 20 individuals were excluded due to self-reported severe simulator sickness or high scores (above the 85th percentile) on the MSSQ-Short \cite{kennedy1993simulator}. The final sample thus consisted of 198 participants, including both students and working professionals with higher education. This group comprised 68 female and 130 male participants (not gender balanced), aged between 17 and 60 years, with an average age of 27.71 years (SD = 8.54). The sample was multinational, with participants from various countries, including Poland, Spain, Ukraine, Italy, and Turkey. All participants had normal or corrected vision and hearing and no history of neurological illness. Individuals with high susceptibility to simulator sickness were not included in the study, as such symptoms could interfere with the perception of subtle guidance cues and introduce unwanted variability.
\subsection{Procedure}
The research received ethical clearance from the pertinent institutional ethics committee to investigate navigation in the VR environment. Upon perusing the requisite documentation and providing informed consent, participants completed a demographic survey and general abilities assessment concerning technology, games, and VR. 

Subsequently, participants engaged in the experimental task. Each participant was randomly assigned to one of the conditions, which included either receiving one of the predefined cues (visual, auditory or tactile) or no cue at all. The distribution of users was as follows: 49 for NC, 33 for WN, 31 for SE, 27 for AM, 30 for LIGHT and 28 for CE. Participants were then asked to navigate the 3D environment, searching for the target object. No explicit reference was made to the participants regarding the nature of the provided cues or the condition they were assigned to. The experiment was conducted indoors to prioritize participant safety, with accompanying operators throughout its duration. The equipment utilized for this experiment exclusively comprised the Meta Pro HMD. 

After completing the task, we held brief conversations with the participants. We asked whether they felt comfortable during the task, whether they noticed any hints, and what the nature of those hints was. Additionally, we provided space for them to share their own comments and observations.


\section{Results}
\label{sec:results}
This section presents the results obtained in the study, structured into two main sections: quantitative statistical analysis and qualitative insights derived from post-experiment user interviews. The first part focuses on objective performance metrics—such as task completion times and success rates—across different types of navigational cues used in the VR environment. The second section addresses the subjective layer of user experience, based on informal post-task interviews. The discussions aimed to explore participants’ decision-making strategies, their awareness of the cues, and whether the cues were perceived as helpful or disruptive to the immersive experience.

\subsection{Statistical Data Analysis}
Before selecting the appropriate statistical procedures, we evaluated the distribution of our data using the Shapiro–Wilk test. As the results indicated significant deviations from normality, we employed the non-parametric Kruskal–Wallis test to compare group medians. The Kruskal–Wallis test yielded a statistically significant result (H = 17.90, p = 0.00046), indicating that at least one group differed from the others. We conducted a Dunn’s post-hoc test with Bonferroni correction to determine which specific group pairs showed statistically significant differences in performance. The results are presented in Tab.~\ref{tab:dunn_extended}.


\begin{table}[h!]
\caption{Results of Dunn’s post-hoc pairwise comparisons between cue types (Bonferroni-adjusted p-values).}
\label{tab:dunn_extended}
\begin{minipage}{\columnwidth}
\centering
\setlength{\tabcolsep}{3pt}
\renewcommand{\arraystretch}{1.1}
\begin{tabular}{p{1.6cm}p{1.1cm}p{1.1cm}p{1.1cm}p{1.1cm}p{1.1cm}p{1.1cm}}
\hline
 & \textbf{CE} & \textbf{LIGHT} & \textbf{NC} & \textbf{WN} & \textbf{SE} & \textbf{AM} \\ \hline
\textbf{CE}    & 1.000 & 0.041 & 0.003 & 1.000 & 1.000 & 1.000 \\
\textbf{LIGHT} & --    & 1.000 & 0.000 & 0.001 & 0.173 & 0.024 \\
\textbf{NC}    & --    & --    & 1.000 & 0.105 & 0.000 & 0.125 \\
\textbf{WN}    & --    & --    & --    & 1.000 & 1.000 & 1.000 \\
\textbf{SE}    & --    & --    & --    & --    & 1.000 & 1.000 \\
\textbf{AM}    & --    & --    & --    & --    & --    & 1.000 \\
\hline
\end{tabular}
\end{minipage}
\end{table}


The statistical analysis reveals several significant differences ($p < 0.05$), suggesting that the type of navigational cue had a measurable impact on participants’ performance in certain pairings. Notably, significant differences were found between CE and both LIGHT and NC conditions, indicating that user performance in the CE condition differed meaningfully from those in both the visual light cue and no-cue scenarios. The LIGHT condition also showed statistically significant differences in comparison with multiple other conditions, including NC, WN, and AM. Furthermore, a significant difference was observed between SE and NC, indicating that performance in the sonar cue condition differed reliably from the no-cue condition. In contrast, no statistically significant differences were found between several other condition pairs, such as CE vs WN, CE vs SE, or AM vs SE. This lack of significance suggests that, within these pairings, task performance was statistically comparable under the given sample size and variability.

Figures ~\ref{fig:visual2} and ~\ref{fig:progress1} provide complementary insights into user performance under different navigation assistance conditions in the VR environment. 


\begin{figure*}[h!]
  \centering
  \begin{subfigure}{0.40\linewidth}
    \centering
    \includegraphics[width=\linewidth]{dane.png}
    \caption{Box plot of data series (NC - no cue, LIGHT - intensity of light cue, WN - spatial white noise cue, SE - sonar effect cue, AM - air movement cue,  CE - compass effect.)}
    \label{fig:visual2}
  \end{subfigure}
  \hfill
  \begin{subfigure}{0.546\linewidth}
    \centering
    \includegraphics[width=\linewidth]{progress.png}
    \caption{Progression of users’ success rate over time in locating a target object in the VR environment, grouped by navigation assistance type.}
    \label{fig:progress1}
  \end{subfigure}
  \hfill
\end{figure*}

Fig.~\ref{fig:visual2} presents a box plot of task completion times, revealing substantial differences across cue types. Participants in the NC (no cue) condition exhibited the longest completion times, indicating significant difficulty in locating the target without any guidance. In contrast, the CE (compass-based haptic cue) and SE (sonar cue) conditions resulted in the shortest completion times, suggesting these directional feedback mechanisms were particularly effective. CE and SE also exhibited the lowest inter-quartile ranges of completion time, highlighting their robustness across users. The LIGHT condition showed strong performance as well, with mean times notably lower than in NC and comparable to CE and SE, though its spread was the largest, indicating higher variability in user performance. The WN (white noise) and AM (air movement) conditions yielded moderate results with greater dispersion, suggesting less consistent effectiveness.

Fig.~\ref{fig:progress1} complements these findings by illustrating the cumulative success rate of users over time. The progression curves show that users in the CE, LIGHT, and SE conditions reached target objects faster and more consistently, with their success rates approaching 100\% within the first 100–200 seconds. Conversely, the NC condition exhibited a much slower and more gradual increase, reflecting users' challenges in navigating without cues. The WN and AM conditions again occupied a middle ground, showing moderate speed and reliability.


The user navigation patterns were analyzed to assess both the efficiency of movement and the points of hesitation during object searches. As shown in Fig.~\ref{fig:hm}, the heat map illustrates the pathways taken and highlights areas where users spent extended periods. These moments of prolonged presence suggest potential difficulty or deliberation, offering insights into user decision-making and interaction within the environment. In the case of the LIGHT cue condition (n = 30), participants demonstrated a noticeable distribution pattern: 15 users were able to locate the target quickly, 9 required significantly more time, and the remaining 6 participants showed mixed behaviors that could not be clearly classified into either group. This trend is clearly visible in the figure — participants in the first group immediately noticed the cue and moved toward it (see Fig.~\ref{fig:light1}), while the others wandered aimlessly (see Fig.~\ref{fig:light2}). This observation is supported by the largest standard deviation within this group.


\begin{figure}[h!]
  \centering
  \begin{subfigure}{0.49\linewidth}
    \centering
    \includegraphics[width=\linewidth]{light1.png}
    \caption{}
    \label{fig:light1}
  \end{subfigure}
  \hfill
  \begin{subfigure}{0.49\linewidth}
    \centering
    \includegraphics[width=\linewidth]{light2.png}
    \caption{}
    \label{fig:light2}
  \end{subfigure}
  \caption {Heat map of user navigation paths and time spent in specific locations (a) LIGHT-type guidance - total search time 466.52~s; (b) LIGHT-type guidance - total search time 35.56~s.}
  \label{fig:hm}
\end{figure}



To assess how directly users navigated toward the target, we calculated a \emph{path tortuosity index}, defined as the ratio of the total flown distance to the straight-line distance between the start and the target. A value of 1.0 indicates a perfectly straight trajectory, while higher values reflect increasingly winding, exploratory paths. For example, a ratio of 4 means that the path was four times longer than the direct route. CE and SE produced the most efficient trajectories (mean 2.97 and 3.50, respectively), whereas LIGHT and NC conditions resulted in the most meandering paths (mean 5.03 and 4.55). Tab.~\ref{tab:avg_sd} presents the mean and standard deviation for each condition.






\begin{table}[h!]
\caption{Mean path tortuosity index (AVG) and standard deviation (SD) for each condition.}
\label{tab:avg_sd}
\begin{minipage}{\columnwidth}
\centering
\setlength{\tabcolsep}{4pt}
\renewcommand{\arraystretch}{1.1}
\begin{tabular}{p{2.4cm}p{1.6cm}p{1.6cm}}
\hline
\textbf{cue type} & \textbf{AVG} & \textbf{SD} \\ \hline
NC     & 4.55 & 4.32 \\
LIGHT  & 5.03 & 5.92 \\
WN     & 3.33 & 2.12 \\
SE     & 3.50 & 3.15 \\
AM     & 3.34 & 2.59 \\
CE     & 2.97 & 2.69 \\
\hline
\end{tabular}
\end{minipage}
\end{table}


\begin{table}[h!]
\caption{Correlation matrix between task completion time, MPTI and participants’ self-assessed abilities in three domains: technical skills (Tech ab.), gaming skills (Game ab.), VR-related experience (VR ab.).}
\label{tab:correlation_matrix}
\begin{minipage}{\columnwidth}
\centering
\setlength{\tabcolsep}{3pt}
\renewcommand{\arraystretch}{1.1}
\begin{tabular}{p{2.6cm}p{1.3cm}p{1.3cm}p{1.3cm}p{1.3cm}p{1.3cm}}
\hline
                  & \textbf{Time} & \textbf{MPTI} & \textbf{Tech} & \textbf{Game} & \textbf{VR} \\ \hline
Time        & 1.000  & 0.891 & -0.899 & -0.731 & -0.840 \\
MPTI        & 0.891  & 1.000 &  0.745 &  0.866 &  0.672 \\
Tech        & -0.899 & 0.745 & 1.000  & -0.734 & -0.842 \\
Game        & -0.731 & 0.866 & -0.734 & 1.000  & -0.871 \\
VR          & -0.840 & 0.672 & -0.842 & -0.871 & 1.000  \\
\hline
\end{tabular}
\end{minipage}
\end{table}






Figure~\ref{fig:survey} presents the results of a questionnaire assessing participants' self-reported competencies across three domains: technical abilities, gaming experience, and familiarity with virtual reality. Responses were recorded on a five-point Likert scale, ranging from "very low" to "very high," and are visualized as stacked horizontal bar charts showing the distribution of responses in each category.

  \begin{figure}
    \centering
    \includegraphics[width=0.7\linewidth]{survey.png}
    \caption{Questionary results - self-reported competencies across three domains: technical abilities, gaming experience, and familiarity with virtual reality.}
    \label{fig:survey}
  \end{figure}


The majority of participants rated their technical abilities as either high or very high, indicating a generally strong level of digital and technological proficiency among the sample. A similar trend is observed in the games abilities category, with most participants placing themselves in the moderate to very high range, reflecting a relatively experienced user group in terms of gaming skills. In contrast, VR abilities showed a broader and more varied distribution. While a portion of participants still reported high or very high familiarity with VR, a noticeable number rated their experience as low or very low. This suggests that, despite technical and gaming proficiency, many users had limited prior exposure to virtual reality environments.


In order to calculate the correlations between task completion time and self-assessed skills, we first divided the task completion times into three intervals: up to 100 seconds, between 100 and 300 seconds, and over 300 seconds. We then examined the correlation with self-assessed skills in technical, games, and VR abilities. The results are presented in Tab.~\ref{tab:correlation_matrix}.

The data reveal strong negative correlations between task completion time and all three self-assessed ability categories. The correlation between time and technical abilities was high (r = 0.899), suggesting that participants who rated themselves as more technically skilled tended to complete the task more efficiently. Similarly, strong negative associations were found between time and VR experience (r = –0.840), as well as between time and gaming ability (r = –0.731), indicating that greater familiarity with immersive and interactive technologies was linked to improved task performance.

MPTI was also strongly positively correlated with task completion time (r = 0.891), meaning that participants who took longer to finish the task tended to follow less direct, more winding paths. Conversely, MPTI was moderately to strongly negatively correlated with technical abilities (r = –0.745), gaming abilities (r = –0.866), and VR experience (r = –0.672). This suggests that higher self-assessed skills in these domains were associated with more efficient navigation paths in the VR environment.

Additionally, the table shows high intercorrelations among the self-assessed abilities themselves. For instance, gaming ability and VR ability were very strongly correlated (r = –0.871), implying that participants experienced in digital games also tended to be more comfortable in virtual reality environments. Overall, these results suggest that higher self-assessed competence in technical, gaming, and VR domains was consistently associated with faster task completion, and that these skill areas are closely interrelated within the participant sample.

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\subsection{Post-Experience Interview}
During the interviews, users in the NC group suggested that they relied on logic when searching for the target, specifically looking for an anchor on the beach or in shallow waters. We recorded 16 such instances where participants clearly avoided the green hills, confirming in the interview that they did not expect to find the anchor there. This suggests the importance of affordances for VR users.

In the WN group, as many as 15 participants reported that the white noise was distracting, to the point that it hindered their ability to focus on the task. They did not recognize that the noise could serve as a spatial cue, with its volume increasing as they approached the target.

In the SE group, 19 participants figured out that the sonar effect was a cue, with 10 of them citing their experience with video games. Two participants, however, perceived the sonar sound as a warning and actively tried to distance themselves from the area where the sonar effect was most intense.

In the AM group, 4 participants did not notice the effect at all, while 10 mentioned that they recognized it as a potential cue, but only after some time. The remaining 13 participants declared that they immediately realized its significance.

In the CE group, 6 participants did not realize that the controller vibrations were intended as a directional cue. One user even reported being irritated by the constant vibration, interpreting it as a technical glitch. Another participant misattributed the haptic feedback to simulated drone motion, describing it as a kind of “microturbulence” that enhanced immersion. The remaining participants recognized the vibrations as intentional guidance and used them effectively to locate the target.

The most intriguing phenomenon observed with the LIGHT system was that 8 out of 9 users, even after receiving a detailed explanation of its guidance mechanism, failed to perceive the intended hint. Interestingly, even when we explicitly pointed out the exact location of the illumination, these users still did not notice it. This suggests that the issue may be linked to the subjective way the human eye compensates for brightness. Investigating the minimum level of illumination required for universal detectability could provide valuable insights, especially since other participants perceived the guidance effortlessly and immediately. What makes this observation particularly compelling is the stark contrast between the extremes: while the system had a highly effective influence on some users, others displayed a complete lack of awareness of its guidance. This duality underscores the need for further investigation into individual differences in perception.

\section{Conclusion}
\label{sec:conc}
This study examined the effectiveness of subtle wayfinding cues in virtual reality by comparing six experimental conditions involving visual, auditory, and haptic guidance. Participants navigated a virtual island using a drone-like locomotion system to locate a hidden target. Cue types included no cue (NC), white noise (WN), sonar effect (SE), air movement (AM), light intensity (LIGHT), and haptic compass feedback (CE).

The analysis showed that several cue types (LIGHT, SE, CE) differed significantly from NC in at least some comparisons, whereas others did not produce statistically significant improvements over NC. In particular, no statistically significant difference was found between NC and WN, and there were no significant differences between SE, CE, and WN. Therefore, although descriptive statistics suggest shorter times for SE and CE, these differences were not confirmed by inferential tests (p~$>$~0.05), and claims about one cue being consistently superior are not supported by the data.

Visual cues produced more mixed results. The LIGHT cue was highly effective for some users but went completely unnoticed by others, even after explanation. The AM cue (animated sand vortex) was better integrated into the environment and generally more detectable, but did not reach the same performance levels as SE or CE. White noise, although dynamic, was frequently interpreted as ambient background sound, reducing its functional value as a navigational aid.

Our findings suggest that continuous, egocentric cues (SE and CE) were more effective not due to higher inherent salience, but because users tended to recognize and interpret them more reliably and consistently across varying scene complexities. In visually dense or cluttered environments, the perceptibility of subtle graphical overlays significantly decreases, leading users to rely more strongly on alternative modalities such as auditory or haptic signals. This observation aligns with principles of Bayesian cue integration~\cite{alais2004ventriloquist}, which predict that when one sensory channel becomes unreliable, the brain automatically assigns greater weight to other, more trustworthy sources of information. Furthermore, the advantage of SE and CE cues is reinforced by their immunity to visual occlusion and by the well-documented auditory looming effect: a sequence of accelerating audio pings naturally captures peripheral attention and conveys a sense of urgency or approach. In contrast, a distant static visual indicator—such as a light pillar—can easily remain unnoticed if it does not intersect with the user’s current field of view. Analysis of user trajectory patterns corroborates this: when non-visual cues were available, participants demonstrated earlier directional certainty and more direct paths towards targets, whereas with purely visual cues like LIGHT, their paths were more exploratory and hesitant, suggesting a higher degree of search behavior and uncertainty.

Overall, the results suggest that certain subtle cues can enhance navigation in VR, but their effectiveness varies across users and modalities. The absence of statistical differences between several cue types, even when descriptive trends appeared, underscores the importance of basing conclusions on statistically supported effects and avoiding overreliance on descriptive measures alone.  Moreover, the absence of significant differences in several cue pairings (e.g., between CE and SE) indicates that these cues may offer comparable benefits in certain contexts, rather than one being universally superior. 

Future work should explore adaptive cue systems that adjust to user preferences and context, potentially incorporating physiological feedback (e.g., heart rate or gaze behavior) to personalize the experience. In addition, cross-modal combinations or layered cue strategies could be investigated to further enhance robustness, particularly in complex or time-sensitive VR applications. While this study used a controlled drone-like flying locomotion to isolate the effects of subtle cues, future research should examine how these findings generalize to other navigation methods, diverse VR settings, and longer exposure durations.

Research Ethics Committee\section*{Funding}
This work was co-funded by the European Union, Erasmus+ Programme (Project no. 2023-1-PL01-KA220-HED-000157492).  Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Education and Culture Executive Agency (EACEA). Neither the European Union nor EACEA can be held responsible for them.


\bibliography{sn-bibliography}% common bib file
%% if required, the content of .bbl file can be included here once bbl is generated
%%\input sn-article.bbl

\end{document}
