Progressive co-adaptation in human-machine interaction

In this paper we discuss the concept of co-adaptation between a human operator and a machine interface and we summarize its application with emphasis on two different domains, teleoperation and assistive technology. The analysis of the literature reveals that only in few cases the possibility of a temporal evolution of the co-adaptation parameters has been considered. In particular, it has been overlooked the role of time-related indexes that capture changes in motor and cognitive abilities of the human operator. We argue that for a more effective long-term co-adaptation process, the interface should be able to predict and adjust its parameters according to the evolution of human skills and performance. We thus propose a novel approach termed progressive co-adaptation, whereby human performance is continuously monitored and the system makes inferences about changes in the users' cognitive and motor skills. We illustrate the features of progressive co-adaptation in two possible applications, robotic telemanipulation and active vision for the visually impaired

Effects of Haptic Feedback on the Wrist during Virtual Manipulation

We propose a haptic system for virtual manipulation to provide feedback on the user's forearm instead of the fingertips. In addition to visual rendering of the manipulation with virtual fingertips, we employ a device to deliver normal or shear skin-stretch at multiple points near the wrist. To understand how design parameters influence the experience, we investigated the effect of the number and location of sensory feedback on stiffness perception. Participants compared stiffness values of virtual objects, while the haptic bracelet provided interaction feedback on the dorsal, ventral, or both sides of the wrist. Stiffness discrimination judgments and duration, as well as qualitative results collected verbally, indicate no significant difference in stiffness perception with stimulation at different and multiple locations.Comment: 2 pages, work-in-progress paper on haptics symposium, 202

Haptic Sketches on the Arm for Manipulation in Virtual Reality

We propose a haptic system that applies forces or skin deformation to the user's arm, rather than at the fingertips, for believable interaction with virtual objects as an alternative to complex thimble devices. Such a haptic system would be able to convey information to the arm instead of the fingertips, even though the user manipulates virtual objects using their hands. We developed a set of haptic sketches to determine which directions of skin deformation are deemed more believable during a grasp and lift task. Subjective reports indicate that normal forces were the most believable feedback to represent this interaction.Comment: 2 pages, work in progres

The Rubber Hand Illusion: Feeling of Ownership and Proprioceptive Drift Do Not Go Hand in Hand

In the Rubber Hand Illusion, the feeling of ownership of a rubber hand displaced from a participant's real occluded hand is evoked by synchronously stroking both hands with paintbrushes. A change of perceived finger location towards the rubber hand (proprioceptive drift) has been reported to correlate with this illusion. To measure the time course of proprioceptive drift during the Rubber Hand Illusion, we regularly interrupted stroking (performed by robot arms) to measure perceived finger location. Measurements were made by projecting a probe dot into the field of view (using a semi-transparent mirror) and asking participants if the dot is to the left or to the right of their invisible hand (Experiment 1) or to adjust the position of the dot to that of their invisible hand (Experiment 2). We varied both the measurement frequency (every 10 s, 40 s, 120 s) and the mode of stroking (synchronous, asynchronous, just vision). Surprisingly, with frequent measurements, proprioceptive drift occurs not only in the synchronous stroking condition but also in the two control conditions (asynchronous stroking, just vision). Proprioceptive drift in the synchronous stroking condition is never higher than in the just vision condition. Only continuous exposure to asynchronous stroking prevents proprioceptive drift and thus replicates the differences in drift reported in the literature. By contrast, complementary subjective ratings (questionnaire) show that the feeling of ownership requires synchronous stroking and is not present in the asynchronous stroking condition. Thus, subjective ratings and drift are dissociated. We conclude that different mechanisms of multisensory integration are responsible for proprioceptive drift and the feeling of ownership. Proprioceptive drift relies on visuoproprioceptive integration alone, a process that is inhibited by asynchronous stroking, the most common control condition in Rubber Hand Illusion experiments. This dissociation implies that conclusions about feelings of ownership cannot be drawn from measuring proprioceptive drift alone

Tickling the CMB damping tail: scrutinizing the tension between the ACT and SPT experiments

The Atacama Cosmology Telescope (ACT) and the South Pole Telescope (SPT) have recently provided new, very precise measurements of the cosmic microwave background (CMB) anisotropy damping tail. The values of the cosmological parameters inferred from these measurements, while broadly consistent with the expectations of the standard cosmological model, are providing interesting possible indications for new physics that are definitely worth of investigation. The ACT results, while compatible with the standard expectation of three neutrino families, indicate a level of CMB lensing, parametrized by the lensing amplitude parameter A_L, that is about 70% higher than expected. If not a systematic, this anomalous lensing amplitude could be produced by modifications of general relativity or coupled dark energy. Vice-versa, the SPT experiment, while compatible with a standard level of CMB lensing, prefers an excess of dark radiation, parametrized by the effective number of relativistic degrees of freedom N_eff. Here we perform a new analysis of these experiments allowing simultaneous variations in both these, non-standard, parameters. We also combine these experiments, for the first time in the literature, with the recent WMAP9 data, one at a time. Including the Hubble Space Telescope (HST) prior on the Hubble constant and information from baryon acoustic oscillations (BAO) surveys provides the following constraints from ACT: N_eff=3.23\pm0.47, A_L=1.65\pm0.33 at 68% c.l., while for SPT we have N_eff=3.76\pm0.34, A_L=0.81\pm0.12 at 68% c.l.. In particular, the A_L estimates from the two experiments, even when a variation in N_eff is allowed, are in tension at more than 95% c.l..Comment: 7 pages, 7 figures, v.2. some typos and sentences correcte

Timing and Time Perception: Procedures, Measures, and Applications

Timing and Time Perception: Procedures, Measures, and Applications is a one-of-a-kind, collective effort to present the most utilized and known methods on timing and time perception. Specifically, it covers methods and analysis on circadian timing, synchrony perception, reaction/response time, time estimation, and alternative methods for clinical/developmental research. The book includes experimental protocols, programming code, and sample results and the content ranges from very introductory to more advanced so as to cover the needs of both junior and senior researchers. We hope that this will be the first step in future efforts to document experimental methods and analysis both in a theoretical and in a practical manner

Musical Scales in Tone Sequences Improve Temporal Accuracy

Predicting the time of stimulus onset is a key component in perception. Previous investigations of perceived timing have focused on the effect of stimulus properties such as rhythm and temporal irregularity, but the influence of non-temporal properties and their role in predicting stimulus timing has not been exhaustively considered. The present study aims to understand how a non-temporal pattern in a sequence of regularly timed stimuli could improve or bias the detection of temporal deviations. We presented interspersed sequences of 3, 4, 5, and 6 auditory tones where only the timing of the last stimulus could slightly deviate from isochrony. Participants reported whether the last tone was ‘earlier’ or ‘later’ relative to the expected regular timing. In two conditions, the tones composing the sequence were either organized into musical scales or they were random tones. In one experiment, all sequences ended with the same tone; in the other experiment, each sequence ended with a different tone. Results indicate higher discriminability of anisochrony with musical scales and with longer sequences, irrespective of the knowledge of the final tone. Such an outcome suggests that the predictability of non-temporal properties, as enabled by the musical scale pattern, can be a factor in determining the sensitivity of time judgments