Perception

Thermal and tactile sensations interact in shaping how we perceive our environment. These interactions rely on the activity of distinct but converging somatosensory pathways and may be altered by aging. In this study, we investigated how innocuous thermal stimulation modulates tactile sensitivity in healthy young and older adults. Mechanical detection thresholds (MDTs) were measured on the dorsal hand using a standardized protocol, while non-painful thermal stimuli were applied as follows: cold (20 °C) and warm (40 °C) either ipsilaterally or contralaterally to the testing site, and a neutral temperature (32 °C) applied only ipsilaterally. Two thermal stimulation methods were used: a localized contact thermode and a global air-based thermal chamber. Results showed that cold stimulation applied ipsilaterally to the tested hand significantly increased MDTs in both age groups, indicating reduced tactile sensitivity. This effect was consistent across stimulation methods, but stronger with the thermode and more pronounced in older adults. Neither warm nor contralateral thermal stimulation produced significant modulation, and neutral temperature had no effect, confirming the specificity of the cold-induced modulation. These findings indicate that cold input inhibits tactile sensitivity in a spatially and modality-specific manner. The absence of contralateral effects supports a segmental, rather than supraspinal, mechanism of thermo-tactile interaction. These results contribute to our understanding of age-related changes in multisensory integration and may inform the development of sensory assessment tools and therapeutic approaches tailored for older individuals.

This study examined the emotion recognition patterns as a function of facial expression speed and intensity by using dynamic facial expression stimuli. Ninety-six university students participated in an emotion identification task, viewing computer-presented facial expressions depicting six basic emotions. Each emotion was morphed to vary across four intensity levels (20%, 40%, 60%, and 80%) and four facial expression speeds (250 ms, 500 ms, 750 ms, and 1,000 ms). A repeated-measures ANOVA was conducted to compare the effects of emotion, intensity, and facial expression speed on accuracy, false alarm rate, sensitivity, and response time. Significant two-way and three-way interactions were observed. Simple effects analyses revealed that each emotion demonstrated distinct optimal combinations of intensity and facial expression speed for accurate, sensitive, and fast recognition. Furthermore, recognition was optimized when expression speed matched intensity within each intensity level: low-intensity expressions were better recognized at faster speeds, while high-intensity expressions were better recognized at slower speeds. These findings suggest that emotion recognition varies systematically with specific combinations of facial expression speed and intensity, highlighting the importance of dynamic features in understanding facial emotion perception.

High-frequency vibrations from manual exploration of natural surfaces are crucial for differentiating materials. These signals depend not only on the spatial structure of materials’ surfaces but also on exploration speed. How we achieve speed constant material perception, even in passive perception in which the texture is moved across the finger, is an open question. Here, we systematically varied exploration speed and recorded vibratory signals from human explorations of 74 material samples. We report that natural materials’ power spectra can be described by the 1/f^s function, with the exponent s differentiating between materials. Crucially, s is speed constant and can explain human correct and mistaken material classifications. Furthermore, s correlates with the highest layer of a speed constant neural network trained to classify natural materials and can be computed from the ratio of tactile afferents’ (RA to PC) activation. We propose that s is a biologically plausible solution of speed constancy.

Active learning, or control over the visual sensory experience during object learning, has been shown to facilitate visual object recognition in adults, relative to a unisensory passive experience. Recent research suggests adding haptics to a naturalistic visual encoding environment, creating a multisensory active experience, also facilitates object recognition relative to unisensory and multisensory conditions with visual encoding via a computer screen. Until now, this active advantage has been tested through the visual modality. To expand on the existing literatures, we tested how multisensory control of real 3D objects, direct access to sensory information, and ownership of the sensory experience affected haptic object recognition. Results revealed that multisensory direct access (sensory information provided directly through the environment, rather than through a computer screen) to object shape facilitated accuracy in a haptic test greater than only haptic information. This suggests an importance for visual information for haptic recognition, but importantly within this multisensory experience. Interestingly, the source of the visual object structure (actions viewed in the direct environment or via a computer screen) did not impact haptic recognition.

Perinatal and pediatric brain damages in children, such as those caused by perinatal stroke, often results in motor and sensory impairments that compromise autonomy and quality of life. Such conditions may also disrupt multisensory integration, which is essential for goal-directed actions. While previous studies have examined multisensory processing using laboratory-based paradigms, they often lacked ecological validity. To address this issue, we developed MSICLIMB, a novel climbing wall equipped with smart holds that emit auditory (A), visual (V), and audiovisual (VA) cues, which enables the study of multisensory integration in a dynamic, action-oriented context. We compared children with motor impairments to typically developing peers, measuring their reaching times (RT) in response to randomly presented sensory cues. Children with motor impairments exhibited significantly slower RT across all conditions. However, both groups showed faster RT to multisensory stimuli, highlighting the facilitative effect of multisensory integration. RTs improved over trials, particularly in the clinical group, suggesting learning potential. Age was also a significant factor, with older children demonstrating faster responses and reduced group differences. MSICLIMB is an innovative tool that can be used to assess and potentially train multisensory integration through ecologically valid sensorimotor tasks. It has promising applications in both clinical and typical populations.

There has been an explosion of interest in sonic seasoning in recent years, building on the emerging literature concerning the existence of consensual crossmodal correspondences between sonic and gustatory properties. However, to date, a musical match for the metallic taste has not been reported (nor looked for). Here, based on the authors’ intuition, we tested, and by so doing demonstrate, that the sound of the theremin, associated with old sci-fi movies is strongly associated with a metallic taste.