Negation has long been a central topic in psychology, linguistics and the cognitive sciences with interest in its nature and functions continuing to grow. Understanding negation is cognitively demanding: negative sentences are often associated with higher processing costs and error rates. A prominent view holds that comprehending negation involves representing two mental models - the negated situation and the actual one - and selectively inhibiting the former. Despite the early emergence of no in children’s vocabularies, full mastery of sentential negation develops relatively late. Beyond its role as a logical operator, negation serves diverse discourse functions, from denying plausible assumptions to correcting misinformation. While negation is a linguistic universal, its realization varies substantially across languages, and the processing consequences of these differences remain underexplored. Moreover, the influence of negation extends beyond language, shaping memory, attitudes, and behavior.

Part 1 of this double symposium examines how negation is typically interpreted, which mechanisms are engaged, and how these processes play out cross-linguistically. Elena Albu asks how negation interacts with relative adjectives (Is a boy who is not short of medium height - or tall?). Claudia Maienborn and Frauke Buscher use denial contexts to contrast rejections of world-knowledge violations with rejections of semantic violations. Mechteld Van den Hoek Ostende probes whether inhibitory control is routinely recruited by studying children with ADHD, who often show difficulties with inhibition. Daniel Maurer employs negated cues in a spatial cueing paradigm to test whether comprehenders can orient directly to the actual facts or must first activate - and then inhibit - the negated alternative. Finally, Svetlana Mnogogreshnova compares Spanish and German, asking whether the earlier placement of the negation marker in Spanish relative to German modulates the mechanisms engaged during processing.