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Individual differences in vibrotactile perception underscore the growing importance of personalization as haptic feedback becomes more prevalent in interactive systems. We propose Vibrotactile Preference Learning (VPL), a system that captures user-specific preference spaces over vibrotactile parameters via Gaussian-process-based uncertainty-aware preference learning. VPL uses an expected information gain-based acquisition strategy to guide query selection over 40 rounds of pairwise comparisons of overall user preference, augmented with user-reported uncertainty, enabling efficient exploration of the parameter space. We evaluate VPL in a user study (N = 13) using the vibrotactile feedback from a Microsoft Xbox controller, showing that it efficiently learns individualized preferences while maintaining comfortable, low-workload user interactions. These results highlight the potential of VPL for scalable personalization of vibrotactile experiences. 

Both haptic signals and simple, non-anthropomorphic robots can convey complex emotions and enhance remote communication. In this study, we integrated a zoomorphic socially expressive Blossom robot and a haptic sleeve to create a novel multimodal telepresence platform for remote social interaction. Through a within-subject user study with 16 participants, we explored the individual and combined effects of socially expressive robots and mediated social touch on affective communication and social presence during a semi-collaborative LEGO assembly task. Across all participants, the robot and wearable device significantly impacted how participants perceived expressions of gratitude, calming, attention-grabbing, and sadness, evaluated through self-reported valence and arousal. The robot and wearable device in our setting did not show a significant effect on social presence. The observations from this exploratory study can inform the design of multimodal telepresence systems and interactions using non-anthropomorphic robots and mediated touch. 

Social touch is a common method of communication between individuals, but touch cues alone provide only a glimpse of the entire interaction. Visual and auditory cues are also present in these interactions, and increase the expressiveness and recognition of the conveyed information. However, most mediated touch interactions have focused on providing only haptic cues to the user. Our research addresses this gap by adding visual cues to a mediated social touch interaction through an array of LEDs attached to a wearable device. This device consists of an array of voice-coil actuators that present normal force to the user’s forearm to recreate the sensation of social touch gestures. We conducted a human subject study (N = 20) to determine the relative importance of the touch and visual cues. Our results demonstrate that visual cues, particularly color and pattern, significantly enhance perceived realism, as well as alter perceived touch intensity, valence, and dominance of the mediated social touch. These results illustrate the importance of closely integrating multisensory cues to create more expressive and realistic virtual interactions. 

The lifetime of tropospheric O3 is difficult to quantify because we model O3 as a secondary pollutant, without direct emissions. For other reactive greenhouse gases like CH4 and N2O, we readily model lifetimes and timescales that include chemical feedbacks based on direct emissions. Here, we devise a set of artificial experiments with a chemistry-transport model where O3 is directly emitted into the atmosphere at a quantified rate. We create 3 primary emission patterns for O3, mimicking secondary production by surface industrial pollution, that by aviation, and primary injection through stratosphere–troposphere exchange (STE). The perturbation lifetimes for these O3 sources includes chemical feedbacks and varies from 6 to 27 days depending on source location and season. Previous studies derived lifetimes around 24 days estimated from the mean odd-oxygen loss frequency. The timescales for decay of excess O3 varies from 10 to 20 days in northern hemisphere summer to 30 to 40 days in northern hemisphere winter. For each season, we identify a single O3 chemical mode applying to all experiments. Understanding how O3 sources accumulate (the lifetime) and disperse (decay timescale) provides some insight into how changes in pollution emissions, climate, and stratospheric O3 depletion over this century will alter tropospheric O3. This work incidentally found 2 distinct mistakes in how we diagnose tropospheric O3, but not how we model it. First, the chemical pattern of an O3 perturbation or decay mode does not resemble our traditional view of the odd-oxygen family of species that includes NO2. Instead, a positive O3 perturbation is accompanied by a decrease in NO2. Second, heretofore we diagnosed the importance of STE flux to tropospheric O3 with a synthetic “tagged” tracer O3S, which had full stratospheric chemistry and linear tropospheric loss based on odd-oxygen loss rates. These O3S studies predicted that about 40% of tropospheric O3 was of stratospheric origin, but our lifetime and decay experiments show clearly that STE fluxes add about 8% to tropospheric O3, providing further evidence that tagged tracers do not work when the tracer is a major species with chemical feedbacks on its loss rates, as shown previously for CH4.