Subjective Preference Research Articles

Effects of lighting on task performance, stress and thermal sensation in working environments

Studies have shown that the correlated colour temperature (CCT) of light significantly influences individuals engaged in study and work activities. However, the impact of CCT on stress and task performance, particularly when considering subjective preferences and experiences, has been explored only to a limited extent. This study aims to investigate the relationship between CCT, thermal sensation vote, stress levels and task performance. Forty-two healthy participants (21 female and 21 male, aged 20 to 53 years) participated in the experimental study. Participants completed a paper-based task and subjective questionnaires across three sessions, each conducted under different CCTs (2700 K, 4000 K and 6500 K). During these sessions, electroencephalogram (EEG) and heart rate variability were monitored to objectively assess stress levels. The study primarily focused on the activity of EEG alpha and theta waves in response to varying CCT degrees. Notably, significant activity was observed in the frontal lobes at 2700 K, particularly related to the frontal theta wave. Statistical significance was also identified in different brain regions in both alpha and theta waves among participants who demonstrated successful task performance. Additionally, participants reported optimal thermal comfort at 2700 K, which was associated with enhanced task performance and reduced stress levels.

(In)efficiency of Beneish M Score model in detecting fraud in financial statements

The creation and application of accounting standards (International Accounting Standards (IAS), International Financial Reporting Standards (IFRS), American Generally Accepted Accounting Principles (GAAP)) that would have universal acceptability was the guiding idea of the most important accounting authorities when they started the process of defining and adopting accounting rules and procedures (standards), which we could call international professional accounting regulation. However, a certain "rigidity" that became immanent in the aforementioned standards was somewhat "depreciated" by prescribing at least two, and often more, permitted procedures, which put accountants in a position where their subjective preference for a certain procedure can, to a greater or lesser extent, influence the height of the periodic result. In this way, the so-called creative accounting, which with its techniques or methods helps managers, (co)owners, and/or accountants in compiling financial reports that are usually prepared in accordance with legal and professional regulations, but contrary to its spirit, results in an asset-financial and profitable position of a business (accounting entity) that deviates to a greater or lesser extent from what could be characterized as true and fair. Checking the "freedom" in the choice of adequate accounting rules and procedures, i.e., checking the correctness and objectivity of the compiled set of financial reports can be done by applying several methods and techniques developed by forensic accountants, as well as experts from other fields. In the continuation of this article, we will try to explain in more detail the essence of Beneish's M-score model for detecting possible inconsistencies in the asset-financial and yield position of the observed accounting entity, the results that confirm its (in)efficiency, as well as the doubts that still exist and that can raise doubts about the (all) possibility of this model in detecting fraud in financial statements.

Book Recommendation System

This study presents a personalized book recommendation system designed to assist students in selecting appropriate study materials based on their grade levels and subject preferences. Unlike general AI models such as ChatGPT, our system tailors book recommendations by integrating user feedback and leveraging targeted personalization. The development process consisted of multiple iterations involving user-centered design and evaluation, including surveys, low-fidelity prototype testing, and high-fidelity prototype evaluation. Findings show that the system effectively meets the unique needs of students by providing accessible, relevant, and customized recommendations. The results indicate that our personalized approach improves user satisfaction and addresses challenges that traditional book recommendation systems face, such as lack of relevance and complexity in navigation.

TOPSIS prefabricated building construction evaluation based on interval-valued Pythagorean fuzzy numbers based on prospect theory

Prefabricated buildings have a series of advantages such as high efficiency, energy savings, and environmental protection, and are being strongly promoted by the Chinese government. However, due to the late start of prefabricated buildings in China, the installation process of prefabricated components is relatively complex, leading to difficulties in quality and safety control. A novel evaluation methodology integrating the technique for order preference by similarity to ideal solution (TOPSIS) with prospect theory and interval-valued Pythagorean fuzzy numbers (IVPFNs) is proposed. Fully considering the subjective value perceptions of decision-makers when faced with losses and gains, a risk evaluation model is established based on different types of decision-makers. This model is then compared with the weight correction coefficient model from a balanced perspective to prevent bias caused by over-reliance on decision-makers’ subjective preferences. This study establishes an assessment index system for assembly construction risk, considering personnel, materials, machinery, management, and technology factors. By merging prospect theory with the TOPSIS method, the application of Pythagorean fuzzy numbers is refined, enhancing the group decision-making process for evaluating risks in prefabricated construction projects. On the other hand, the prospect theory approach can focus on the actual psychological state of managers during decision-making, addressing the research gap concerning the impact of managers’ psychological states on the evaluation process. The study identifies critical risk factors and suggests specific risk management strategies to improve the risk mitigation capabilities of construction entities, offering a structured approach to enhancing the efficiency and safety of prefabricated construction projects.

Simultaneous multimodal measures for aesthetic evaluation of furniture color and form

The tendency toward the aesthetic preference affects an individual’s intention to purchase furniture. Color and form are two fundamental elements of furniture appearance. However, there is a significant lack of human–computer interaction research on the aesthetic evaluation of furniture with various colors and forms, necessitating a comprehensive study to provide theoretical and empirical support to furniture designers and businesses. Thus, this study introduces a multimodal method by integrating various modalities, which allowed us to investigate the factors that significantly affect subjective preference evaluation and physiological feedback. The results indicated significant correlations between behavioral data, first fixation duration, and average pupil diameter. Meanwhile, the correlation between multimodal measurement data and product aesthetic ratings was analyzed, and an evaluation model of the leisure chair aesthetic correlation mechanism was proposed.

How to Choose an Emollient? Pharmaceutical and sensory attributes for product selection.

Emollients are part of daily body care and have become indispensable therapeutic adjuvants for the treatment of dry skin conditions. Adherence to topical treatments, notably for dry skin conditions, has been reported to be low. The underlying reasons may include insufficient medical and nursing support for product selection, specific product attributes, aspects of product application, and product feel on the skin. Attempts have also been made to portray lipid content, galenic product format, or rheological attributes (pharmaceutical attributes) as adherence-promoting or adherence-preventing properties. In the treatment of dry dermatoses with emollients, there is little information describing and relating to these various features. We explored whether the sensory attributes of selected emollients were associated with common product attributes such as lipid content, viscosity, or galenic product format, and discuss the extent to which this information is useful for product selection. Nine trained panellists evaluated ten selected emollients based on a set of 18 predefined sensory attributes according to a standard guide for sensory descriptive analysis. Viscosity was determined using a rotational rheometer. The emollients had product-specific sensory attributes. Lipid content, viscosity, and galenic product format are not generally indicative of sensory product attributes. Contrary to popular belief, lipid content and viscosity are not generally indicative of sensory product attributes. This is mainly due to the different physicochemical properties of the lipid phase ingredients, which are product-specific and diverse. As most emollients contain significant amounts of volatile ingredients that evaporate during and after application, their galenic format changes dramatically. Therefore, this is not a viable selection criterion. Because refined information on sensory product attributes, as compiled for this study, is rarely available in everyday life, eliciting individual and subjective patient preferences through dialogue remains crucial. Ideally, patient preferences can be elicited from the sample packs.

The Impact of Color Combination on Visual Search Efficiency and User Experience in Human-Machine Interface: A Case Study of Metro Electronic Guide Screen

Color is an important attribute of human-perceived human-machine interface (HMI), and it is unclear which color combinations produce the best performance and user experience in visual search tasks. Taking the metro electronic guide screen (MEGS) as an example, the eye-tracking (E-T) device is used to record the pupil diameter and search time, and the Likert scale is used to evaluate the satisfaction and usability, and the influence of the four factors of background hue, saturation, brightness and text color in HMI on user search efficiency and user experience is discussed in depth. The results show that the recognition efficiency is best when the background hue is medium brightness, medium saturation green with white text color. Meanwhile, the results of user satisfaction and ease of use are basically consistent with the objective experimental results, and there is a certain correlation between the subjective preference of color combination and visual performance.

Q-Learning-Driven Butterfly Optimization Algorithm for Green Vehicle Routing Problem Considering Customer Preference.

This paper proposes a Q-learning-driven butterfly optimization algorithm (QLBOA) by integrating the Q-learning mechanism of reinforcement learning into the butterfly optimization algorithm (BOA). In order to improve the overall optimization ability of the algorithm, enhance the optimization accuracy, and prevent the algorithm from falling into a local optimum, the Gaussian mutation mechanism with dynamic variance was introduced, and the migration mutation mechanism was also used to enhance the population diversity of the algorithm. Eighteen benchmark functions were used to compare the proposed method with five classical metaheuristic algorithms and three BOA variable optimization methods. The QLBOA was used to solve the green vehicle routing problem with time windows considering customer preferences. The influence of decision makers' subjective preferences and weight factors on fuel consumption, carbon emissions, penalty cost, and total cost are analyzed. Compared with three classical optimization algorithms, the experimental results show that the proposed QLBOA has a generally superior performance.

Overexcitability, Grit, and Creative self-efficacy: A Comparative Study of Gifted and General Student’s Art Subject Preference

Objectives This study investigated the differences in overexcitability, grit, and creative self-efficacy between gifted and general students based on their preferences for art subjects. Methods The study involved 77 gifted students and 43 general students in Seoul and Daejeon. The statistical analysis utilized SPSS 27, employing frequency analysis and multivariate analysis of variance (MANOVA) based on art subject preference. Results Results indicate that, compared to general students, gifted students who prefer art subjects exhibit significantly higher levels of overexcitability and creative self-efficacy. Furthermore, when comparing gifted students and general students based on their art subject preferences, overexcitability, grit, and creative self-efficacy all show significant differences. Conclusions These results suggest a correlation between art subject preference, overexcitability, and creative self-efficacy, emphasizing the interrelated nature of giftedness, overexcitability, grit, and creative self-efficacy.

Application of Fuzzy Logic-Based Expert Advisory Systems in Optimizing the Decision-Making Process for Material Selection in Additive Manufacturing.

In the era of Industry 4.0, additive manufacturing (AM) technology plays a crucial role in optimizing production processes, especially for small- and medium-sized enterprises (SMEs) striving to enhance competitiveness. Selecting the appropriate material for AM is a complex process that requires considering numerous technical, economic, and environmental criteria. Fuzzy logic-based advisory systems can effectively support decision-making in conditions of uncertainty and subjective user preferences. This study presents a developed advisory system model that uses the Analytic Hierarchy Process (AHP) method and triangular and trapezoidal membership functions, enabling dynamic adjustment of criterion weights. The results demonstrated that the system achieved 85% alignment with user preferences, confirming its effectiveness. Future research may focus on integrating fuzzy logic with machine learning algorithms to further enhance the system's precision and flexibility.

Evaluation of stress measurement using a wrist-worn device in volunteer subjects under Thai massage and cardio-exercise treatment

Background: Stress is one of the key factors leading to mood disorders. Screening for stress through questionnaires and heart rate variability (HRV) required delicate consideration and expertise for result interpretation. Nowadays, wrist-worn devices, a non-invasive and real-time monitoring technology for assessing stress levels, are widely used. Objective: To evaluate wrist-worn devices for stress measurement and assess the stress responsiveness of Thai massage (TM) and cardio-exercise in volunteers. Materials and methods: Device verification was inferred before distributing the wrist-worn device to volunteers. Fifty volunteers were randomly assigned to 1.5 hours of TM and 4 weeks of cardio-exercise in zones 1-2 as a stress relaxation program. The stress response rate was compared among 3 different stress measurement tools: an HRV device, cortisol level, and a wrist-worn device. Results: Wrist-worn devices’ step count and heart rate function were verified within an acceptable error of <5% and well correlated with the HRV device before starting the assignment. The significantly decreased value of the stress after TM indicated the responsiveness for stress relaxation within an 85% response rate by HRV (p<0.001) and 75% by wrist-worn devices (p=0.002). ><0.001) and 75% by wrist-worn devices (p=0.002). Higher response outcomes were achieved from the cardio-exercise program, resulting in an 80% response rate by cortisol (p<0.001), 83.3% by HRV device (p=0.001), and 90% by the wrist-worn device (p=0.001). Significant agreement of Kappa values for all paired devices under cardio-exercise reveals an acceptable similar response outcome from wrist-worn devices. The responsive outcome between TM and cardio-exercise programs in similar volunteer groups demonstrates no significant difference measured by HRV devices (p=0.375) and wrist-worn devices (p=0.625) using the McNemar test. Conclusion: The data herein suggest that a wrist-worn device’s stress monitoring provides satisfaction with real-time monitoring and long-term records comparable with HRV devices and cortisol measurements. Cardio exercise for 4 weeks of light and very light cardio is suggested as a continuous approach for stress relaxation. The TM program is a passive intervention that may help temporary relaxation compared to continuous cardio exercise according to subjective preference.

Double-level osteotomy (DLO) for varus deformity results in over a decade of mean survival without compromising subsequent total knee arthroplasty function at a mean 26-year follow-up.

Double-level osteotomies (DLOs) have shown promising results for knee joint preservation, however, most ultimately progress in terms of degenerative disease resulting in conversion to total knee arthroplasty (TKA). Therefore, the purpose of this study was to examine the time to TKA conversion, long-term clinical outcomes and revision rates of patients who have undergone TKA after prior ipsilateral DLO. Patients who underwent simultaneous or staged DLO and subsequently underwent conversion to TKA at a single academic institution from 1997 to 2022 were evaluated. The type of osteotomy performed (opening- vs. closing-wedge), osteotomy hardware fixation, when and if osteotomy hardware was removed, implanted TKA components and revision rates were recorded. Postoperative outcomes, including Forgotten Joint Score-12 (FJS-12), Tegner Activity Scale score and subjective knee preference were also obtained. A total of 22 patients (24 knees) underwent TKA following DLO and were followed for an average of 26.1 ± 7.7 years. The average time from DLO to TKA conversion was 14.1 ± 6.5 years, with 70.8% of knees converting to TKA more than 10 years after DLO. The mean follow-up after conversion to TKA was 12.0 ± 7.7 years. Only 12.5% of patients received a varus-valgus or hinged-constrained TKA. At the final follow-up, the mean FJS-12 was 75.8 ± 23.1, while the mean Tegner Activity Scale score was 2.5 ± 1.1. Seventy-seven percent of patients had no subjective knee preference or preferred their DLO-TKA knee. Only two knees (7.4%) underwent subsequent revision after index arthroplasty at a mean of 9.3 years postoperatively. A majority of DLOs (70.8%) converted to TKA after more than a decade. Subsequent TKA function was favorable as most patients had either no subjective knee preference or preferred their DLO-TKA knee. This study demonstrates both long-term joint preservation and uncompromised TKA function after prior DLO. Level IV.

The Impact of Music Subject Preference on Creative Thinking and Creative Personality of Science Gifted Students: Focusing on Music- Science GI-Convergence Education Program

Objectives This study investigated the variations in creative thinking and creative personality based on the music preference of science-gifted secondary school students who participated in a music-science GI-convergence education program. Methods A total of 12 program sessions were conducted for 8th-grade science-gifted students selected in Daejeon, South Korea. Pre- and Post-tests for creative thinking and creative personality were administered. This was analyzed through quantitative and qualitative studies. Results The findings indicate that science-gifted students with a preference for music subjects exhibited significantly higher scores in creative personality compared to those who did not prefer music subjects. In addition, qualitative research results revealed that science-gifted students who preferred music subjects improved their intrinsic motivation through perseverance, passion, imagination, and a keen interest in class while participating in the music-science GI-convergence education program. Conclusions This suggests that their focus was more directed toward music-related learning. These results imply that science gifted students' inclination toward music subjects has a positive effect on the improvement of creative personality by influencing the emotional aspects of creativity expression.

The acquisition of relative clauses and noun phrase accessibility: testing the NPAH in Cantonese

ABSTRACT The Noun Phrase Accessibility Hierarchy (NAPH) posits a subject advantage in extraction from relative clauses and other constructions – a claim supported by numerous cross-linguistic language acquisition studies. However, Chinese languages differ from the majority of the languages hitherto studied in having SVO (head-initial) word order and prenominal relative clauses, a typologically peculiar combination that provides the opportunity to tease apart predictions of various theories of relative clauses. This study uses Cantonese in an experiment on children’s comprehension of relative clauses to investigate the effects of NP accessibility using pair-wise comparisons across the NP positions of subject, direct object, indirect object, and oblique. The results strongly support a universal subject preference and also support, to some extent, the NPAH’s predictions for the acquisition order of relative clauses. In addition, children’s errors reveal a multifactorial influence, suggesting that their processing of relative clauses is affected by semantic prominence and word order canonicity.

Me and AAC - Alternative and Augmented Communication in West Germany from a Biographical and Media Archaeological Perspective

The article presents a case study on the history of Augmentative and Alternative Communication (AAC) in West Germany from the 1980s to the early 2000s, with a regional focus on the state of North Rhine-Westphalia (NRW). The conceptual framework guiding this study is the question of how the meaning and individual experience of assistance evolve in conjunction with the technical development and practical use of speech computers. The article sheds light on the interplay between historical contingency and individual socio-technical situatedness of disabled AAC-users. It brings together two disciplinary perspectives in a dialogue based on interviews, published primary sources, and the description of historical hardware and software. Biographical narratives of AAC users in NRW are combined with a media archaeological case study of the institutional and technological formations and developments of AAC in the region. We discuss assistive technologies as a historically variable phenomenon. Assistance is a precarious undertaking that is constantly renegotiated by new technological developments. Each stage of assistive technology has consequences for everyday communication practices and the provision of communicative assistance, creating possibilities and impossibilities for the use of technology. For AAC users, this means that they find themselves in specific constellations that affect both their relationship with the device and their subjective preferences and established routines. We argue that so-called assistive technologies are involved in the co-constitution of disability, and therefore suggest referring to them as ‘assistive media.’

Visual Improvement With Wavefront-Guided Scleral Lenses for Irregular Corneal Astigmatism.

To report interim results of a single center, randomized, double-blind, crossover-controlled clinical trial comparing wavefront-guided (wfg) scleral lenses (SLs) to traditional scleral lenses (tSLs) for patients with a history of irregular corneal astigmatism (ICA). Thirty-one ICA eyes of 18 participants were reviewed, 23 with keratoconus, six postcorneal refractive ectasia, and two postpenetrating keratoplasty. Patients with corneal or lens opacities were not excluded from participating. Participants underwent a diagnostic lens-based fitting with a tSL with standard spherocylindrical optics. Once the tSL was finalized, a comprehensive wavefront aberrometer-based system was used to capture the residual aberration of the tSL under scotopic conditions without pharmacologic dilation, and these data were used to create a wfgSL. Once the tSL and wgfSL were finalized, a double-blinded, randomized, crossover was conducted where the participants received lens A (tSL or wgfSL) or lens B (the alternative), each worn for a 4±1 week interval. Measurements of the visual acuity (VA) and total higher-order root mean squared (HORMS) were recorded at each interval under controlled lighting conditions. At the final visit, patient subjective preference for lens A or lens B was recorded. The average HORMS for a fixed 5-mm pupil was 0.68±0.31 μm for tSL and 0.29±0.18 μm for wfgSL. Wavefront-guided SL provided an average HORMS improvement of 56% (P<0.001). All eyes showed a reduction in HORMS, ranging from 18% to 83%. Wavefront-guided SL provided an average VA improvement of 0.12±0.11 logMAR (P<0.01). Seventy-one percent of eyes showed one line or greater improvement, 26% showed no improvement, and 3% showed a reduction of VA with the wfgSL. The average VA with tSL was 0.14±0.16 logMAR and 0.03±0.11 logMAR for wfgSL. Seventeen of 18 patients subjectively preferred wfgSL. In eyes with ICA, wfgSL reduced HORMS and improved VA when compared with tSL. Patients subjectively preferred wfgSL to tSL. These interim results demonstrate the feasibility and generalizability of wfgSL in a typical clinical practice environment.

Are you worth the wait? Waiting time modulates the social feedback processing: Evidence from event-related potentials.

Processing social feedback is essential for establishing appropriate social connections. However, social feedback is not always immediate, and the impact of waiting time on social feedback processing remains unexplored. Using electroencephalography (EEG) and event-related potentials (ERPs), the present study investigated how waiting time affects the N170, reward positivity (RewP), and P3. Participants (N = 36) completed a social evaluation task, awaiting feedback from liked and disliked peers with short (800-1200 ms) or long (5000-6000 ms) waiting times. Participants were more motivated to receive feedback from liked peers, and they rated acceptance from liked peers as more pleasant than rejection. Notably, participants found longer waits more worthwhile when receiving acceptance from liked peers, but less worthwhile when awaiting feedback from disliked peers. EEG results revealed that the RewP was increased for long waiting times for feedback from liked peers, and, conversely, reduced for long waiting times for feedback from disliked peers. Additionally, N170 and P3 were found to be sensitive to waiting time, with larger amplitudes for long compared to short waits. Overall, this study demonstrates that waiting time differentially affects social feedback processing, as reflected by changes in the N170, RewP, and P3. Our findings suggest that increased waiting time does not necessarily reduce reward value; it can enhance it depending on subjective social preferences. The increased N170 and P3 amplitudes during longer waits may indicate heightened attentional and memory demands. This study advances our understanding of the neurocognitive mechanisms underlying social decision-making.

Interactive 3D structural design in virtual reality using preference-based topology optimization

Innovative load-bearing structures often emerge from a fine balance between creative forms and engineering principles. While preference-based topology optimization methods have advanced structural design by considering designers’ geometric preferences, they struggle with visualizing and editing complex 3D details crucial for diverse design options. To overcome this bottleneck, here we propose the improved bidirectional evolutionary structural optimization considering subjective preferences (ISP-BESO) method. This method introduces a similarity constraint that enables precise control over subjective preferences in optimized structures. Then, a design exploration strategy is proposed by integrating virtual reality (VR) with topology optimization for the interactive creation of desirable 3D structures. The strategy employs VR sculpting to offer immersive visualization and real-time feedback, guiding material redistribution during optimization. This workflow can iteratively produce innovative and efficient structures. Adjusting target similarity in ISP-BESO steers designs toward performance-driven or preference-driven outcomes. A museum design example demonstrates the practical potential of this strategy.

A VIKOR-Based Sequential Three-Way Classification Ranking Method

VIKOR uses the idea of overall utility maximization and individual regret minimization to afford a compromise result for multi-attribute decision-making problems with conflicting attributes. Many researchers have proposed corresponding improvements and expansions to make it more suitable for sorting optimization in their respective research fields. However, these improvements and extensions only rank the alternatives without classifying them. For this purpose, this text introduces the three-way sequential decisions method and combines it with the VIKOR method to design a three-way VIKOR method that can deal with both ranking and classification. By using the final negative ideal solution (NIS) and the final positive ideal solution (PIS) for all alternatives, the individual regret value and group utility value of each alternative were calculated. Different three-way VIKOR models were obtained by four different combinations of individual regret value and group utility value. In the ranking process, the characteristics of VIKOR method are introduced, and the subjective preference of decision makers is considered by using individual regret, group utility, and decision index values. In the classification process, the corresponding alternatives are divided into the corresponding decision domains by sequential three-way decisions, and the risk of direct acceptance or rejection is avoided by putting the uncertain alternatives into the boundary region to delay the decision. The alternative is divided into decision domains through sequential three-way decisions, sorted according to the collation rules in the same decision domain, and the final sorting results are obtained according to the collation rules in different decision domains. Finally, the effectiveness and correctness of the proposed method are verified by a project investment example, and the results are compared and evaluated. The experimental results show that the proposed method has a significant correlation with the results of other methods, ad is effective and feasible, and is simpler and more effective in dealing with some problems. Errors caused by misclassification is reduced by sequential three-way decisions.

A subjective and objective fusion visual fatigue assessment system for different hardware and software parameters in SSVEP-based BCI applications

With the development of brain-computer interface industry, large amounts of related applications have entered people’s vision. BCI applications based on steady-state visual evoked potentials (SSVEP) are widely used because they do not require pre-training and have high information transmission rates. However, in the actual use of SSVEP stimulus paradigm, the subjects will produce visual fatigue with the use, and fatigue will affect the transmission efficiency. In this experiment, an experimental environment consisting of two paradigm stimulus frequencies (7.5 Hz, 15 Hz), three resolutions (800 × 600, 1280 × 720, 1920 × 1080) and three refresh rates (120 Hz, 240 Hz, 360 Hz) is set up. The Likert scale is used to collect subjective fatigue and preference scores, and the EEG acquisition system and eye tracker are used to collect objective data. Using the proposed information entropy-CRITIC algorithm to combine subjective and objective indicators, a fatigue assessment system (display screen fitness-DSF) is innovated to score different experimental environments. The higher the DSF score, the better the visual experience. The results show that when using the 7.5 Hz SSVEP paradigm, the combination of 360 Hz and 1920 × 1080 can bring the best visual experience. When using the 15 Hz SSVEP paradigm, the combination of 240 Hz and 1280 × 720 is the best. DSF provides powerful help for hardware and software selection guidance and vision protection when using SSVEP-based BCI applications.