Beyond multisensory peripersonal space: Multiple origins of tactile facilitation induced by approaching stimuli.

Whether reaching for an object or avoiding a potential threat, our ability to interact with the world relies on anticipating physical contact with nearby objects. This ability is thought to depend on the facilitation of tactile processing whenever an object enters the region surrounding the body where physical interaction is possible, referred to as 'peripersonal space'. Traditionally, these facilitation effects have been ascribed to the activity of the peripersonal neurons, which show maximal responses when tactile stimuli on the body co-occur with nearby visual or auditory stimuli, and would ultimately influence observable behavioral responses. While this neural account has shaped much of the field's interpretation, recent work has begun to question its sufficiency. Notably, whereas neural responses require spatial alignment of stimuli within reachable space, behavioral facilitation often occurs without such alignment and can extend well beyond the boundaries of reachable space. Building on emerging perspectives, we systematically unpacked additional processes, such as overt expectations, increased attention, and motor resonance, that may contribute to this behavioral facilitation. We argue that tactile facilitation driven by external stimuli, especially those approaching the body, involves a complex interplay of sensory, motor, and cognitive factors not exclusively restricted to peripersonal space nor directly associated with the activity of the peripersonal neurons. We conclude by discussing the conceptual implications and outlining directions for future research that move beyond a neuron-centric view toward a more integrative account of behavioral responses to multisensory stimuli within and outside peripersonal space.