On truth and polarity in negation processing: language-specific effects in non-linguistic contexts

Introduction: This study examines how negation is processed in a nonverbal context (e.g., when assessing triangle not equal triangle) by speakers of a truth-based system like Mandarin and a polarity-based system like English. In a truth-based system, negation may take longer to process because it is typically attached to the negation as a whole (it is not true that triangle does not equal triangle), whereas in polarity-based systems, negation is processed relatively faster because it is attached to just the equation symbol (triangle does not equal triangle), which is processed relatively faster. Our hypothesis was that negation processing routines previously observed for verbal contexts, namely that speakers of Mandarin get slowed down more when processing negative stimuli than positive stimuli compared to speakers of English, also extend to contexts when language use is not obligatory. Methods: To test this, we asked participants to agree/disagree with equations comprising simple shapes and positive '=' or negative 'not equal' equation symbols. English speakers showed a response-time advantage over Mandarin speakers in negation conditions. In a separate experiment, we also tested the contribution of equation symbols 'not equal'/'=' to the cognitive demands by asking participants to judge shape sameness in symbol-free trials, such as triangle square. This comparison allowed us to test whether crosslinguistic differences arise not because of shape congruence judgement but arguably due to negation attachment. Results and discussion: The effect of the 'not equal' symbol on shape congruence was language-specific, speeding up English speakers but slowing down Mandarin speakers when the two shapes differed. These findings suggest language-specific processing of negation in negative equations, interpreted as novel support for linguistic relativity.