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 extend beyond language, shaping memory, attitudes, and behavior.

Part 2 turns to acquisition and to influences of negation beyond language proper. Ulrike Schild shows that even two-year-olds struggle with sentential negation: an eye-tracking study finds no processing difference between “This is a mora” and “This is not a mora.” Chiara Boila examines whether preschoolers—whose executive functions are still maturing—face particular difficulty with negative utterances that require maintaining two pieces of information simultaneously. The remaining three contributions explore how negation shapes cognition outside the linguistic system: Emanuel Schütt investigates its role in attitude formation; Parker Smith tests ironic effects of negation on behavior; and Amit Singh asks how negative utterances influence event apprehension and contrast.