Adaptive user interfaces dynamically change their content, presentation, and behavior to optimize the user experience, which has been primarily evaluated using classic usability measures but to a lesser extent by using neurological measures. While the perceived preference of specific user interface elements, such as graphical adaptive menus, has already been studied, no consensus exists regarding their performance and how to substitute a static menu with an adaptive one. To gain insights into how graphical adaptive menus could influence the user experience and to identify any correlation between users’ performance and their preferences, we conducted an experiment in which forty participants used twenty graphical adaptive menus while their brain activity was captured by employing electroencephalography to derive four measures ( i.e. , cognitive load, engagement, attraction, and memorization). User performance was measured using task completion time, specifically the time to select menu items. Statistical analysis suggested which graphical adaptive menus were significantly better or worse than the static menu, our baseline. These results are used as the basis to suggest implications for software developers and researchers to design more effective adaptive user interfaces.

Adaptive User Interfaces (AUI) play a crucial role in modern software applications by dynamically adjusting interface elements to accommodate users’ diverse and evolving needs. However, existing adaptation strategies often lack real-time responsiveness. Reinforcement Learning (RL) has emerged as a promising approach for addressing complex, sequential adaptation challenges, enabling adaptive systems to learn optimal policies based on previous adaptation experiences. Although RL has been applied to AUIs,integrating RL agents effectively within user interactions remains a challenge.

Abstract Context Adapting the User Interface (UI) of software systems to users’ requirements and their context of use is a challenging task. It involves determining the right adaptation, at the right time and place, to make it valuable for end-users. We believe that recent progress in Machine Learning (ML) techniques could provide useful ways in which to support adaptation more effectively. In particular, Reinforcement Learning (RL) has proven to be effective in planning a sequence of UI adaptations over a long time horizon. However, RL requires either manually specifying a reward function or learning a reward model. Currently there is no empirical evidence supporting the usefulness of reward models for UI adaptation. Objective This paper presents a confirmatory empirical study aimed at investigating the effectiveness of two different approaches to generating reward models in the context of UI adaptation using reinforcement learning: (1) a reward model derived exclusively from predictive Human-Computer Interaction (HCI) models (AUI-HCI), and (2) a reward model derived from predictive HCI models augmented by human feedback (AUI-HCI-HF), compared to non-adaptive (NA) interfaces. Method A controlled experiment with an AB/BA crossover design was conducted to evaluate the impact of these reward models on user experience, measured through objective and subjective engagement, as well as user satisfaction. Our study contributes to the understanding of how reward modeling can facilitate UI adaptation through RL. Results The results showed a significant improvement in objective engagement for AUI-HCI-HF compared to non-adaptive interfaces. However, no significant differences were found between AUI-HCI and non-adaptive interfaces for any of the other measurements, across any conditions. Conclusion Integrating human feedback into RL reward models enhances objective engagement, but its impact on subjective engagement and user satisfaction remains limited. While AUI-HCI-HF shows promise for improving interaction metrics, further research is needed to better align reward models with broader user perceptions and preferences, particularly compared to non-adaptive interfaces.

Background: Adaptive user interfaces have the advantage of being able to dynamically change their aspect and/or behaviour depending on the characteristics of the context of use, i.e. to improve user experience. User experience is an important quality factor that has been primarily evaluated with classical measures (e.g. effectiveness, efficiency, satisfaction), but to a lesser extent with physiological measures, such as emotion recognition, skin response, or brain activity. Aim: In a previous exploratory experiment involving users with different profiles and a wide range of ages, we analysed user experience in terms of cognitive load, engagement, attraction and memorisation when employing twenty graphical adaptive menus through the use of an Electroencephalogram (EEG) device. The results indicated that there were statistically significant differences for these four variables. However, we considered that it was necessary to confirm or reject these findings using a more homogeneous group of users. Method: We conducted an operational internal replication study with 40 participants. We also investigated the potential correlation between EEG signals and the participants’ user experience ratings, such as their preferences. Results: The results of this experiment confirm that there are statistically significant differences between the EEG variables when the participants interact with the different adaptive menus. Moreover, there is a high correlation among the participants’ user experience ratings and the EEG signals, and a trend regarding performance has emerged from our analysis. Conclusions: These findings suggest that EEG signals could be used to evaluate user experience. With regard to the menus studied, our results suggest that graphical menus with different structures and font types produce more differences in users’ brain responses, while menus which use colours produce more similarities in users’ brain responses. Several insights with which to improve users’ experience of graphical adaptive menus are outlined.