Urban well-being is not produced by one ideal environment but by the capacity to encounter difference without losing continuity. The street, square, park, route and neighbourhood function less as isolated containers than as modulations of exposure: sequences of shade, vegetation, frontage, sound, social density, access, familiarity, microclimate and movement that alter what a body can do, perceive, remember and recover from. The decisive urban variable is therefore not simply the quantity of a desirable element—greenery, density, accessibility, public space—but the structured differentiation through which environmental conditions become available across time.

This differential field has an epistemic consequence. Coarse spatial proxies are often too blunt because they describe presence without describing encounter. Spokane’s lot-level coding, Urrutia’s microclimatic plaza analysis, Liu’s critique of arbitrary green buffers and Christensen’s geographically informed momentary assessment all move toward finer coupling between environmental form and lived exposure. Zhang adds temporal correction: familiar areas persist because previous knowledge matters, yet they are continuously revised by subsequent events. Urban evidence becomes stronger when measurement follows the scale at which environments are actually encountered rather than assuming that residence, administrative boundary or aggregate greenness adequately represents exposure. Variation is not noise within this framework; it is productive capacity. Samuelsson’s topodiversity formulates this at metropolitan scale, while Urrutia reaches a parallel conclusion at the scale of the plaza: environments supporting multiple spatial and microclimatic options can support multiple forms of use. Cheng extends the point by refusing the simple nature–city dichotomy. Restoration can be associated with greenery, but also with architectural quality, facilities, serenity, prospect, refuge and person–place relations. A heterogeneous city is therefore not restorative because every fragment is optimal. It is restorative when differentiated conditions remain accessible enough for bodies and practices to redistribute themselves. Movement turns this spatial diversity into temporal experience. Tu and colleagues show that the health effects of walking cannot be assigned only to physical activity; the environments through which movement passes alter psychological outcomes. Christensen’s GEMA literature makes the same problem measurable in real time by coordinating position with momentary states. Zhang shows that repeated movement also reorganises cognition by changing what territory becomes familiar. Routes therefore do more than connect destinations. They sample the city, accumulate environmental evidence and progressively construct a personal field of availability. Exposure acquires duration, recurrence and memory. The political implication is that environmental quality cannot be reduced to a universal prescription. Bryer and colleagues demonstrate both the broad public-health importance of greenspace and the uneven quality of evidence supporting different outcomes. The responsible urban question is consequently not whether greenery, density or walkability are good in themselves, but how specific environmental configurations distribute restorative opportunities, cognitive familiarity, comfortable movement and exposure burdens among different users. Measurement must remain granular enough to detect unevenness and cautious enough not to convert association into causality. Socioplastics can operationalise this field by treating urban form, movement, perception and evidence as mutually transforming relations. The object is neither a static map nor an isolated psychological response, but an archive of differential encounters: what conditions existed, how they were reached, at what temporal grain they were experienced, what forms of familiarity or restoration they enabled, and where those relations changed. Such an archive can move between architectural detail, public-space observation, mobility traces, environmental measurement and longitudinal cognition without flattening them into one score. It gives spatial research a way to preserve both comparability and difference. In Socioplastics, differential exposure becomes the material basis of RelationalAgency.