Exploration of outer space is a mesmerizing and thought-provoking endeavor. The fascination about what may be out there only matches by asking who might be out there. Exopsychology is concerned about how humans think about extraterrestrials, but also how extraterrestrials may think. It strives to find generalizable psychological theories to enrich the Search for Extraterrestrial Intelligence (SETI). Here, we apply the psychological theory of affordance (PTA) and specify the role of the relation between brain, body, environment, and material engagement in the context of SETI. Producing technosignatures requires that a species skillfully realizes the relevant possibilities for action, which the Umwelt offers in all its socio-material richness. These so-called are not fixed but relational to individual and collective available abilities and customs. A successful first contact requires a mutual attunement to species-typical diachronic backdrops, which constitute meaning. One possibility for a meaningful message form and content is the reference to the material environment and its respective engagement. Meaningfulness of affordances is conserved in a form of life and transmitted via social interaction. Considering the affordances within SETI fosters an understanding of how the thinking and behavior of life forms in the Universe emerge in relation to their material environment.