Negative mental representations in infancy.

How do infants' thoughts compare to the thoughts adults express with language? In particular, can infants entertain negative representations, such as not red or not here? In four experiments, we used pupillometry to ask whether negative representations are possible without an external language. Eleven-month-olds were tested on their ability to detect and represent the abstract structure of sequences of syllables, defined by the relations identity and/or negation: AAAA (four identical syllables; Experiment 1), AAA¬A (three times the syllable A and one final syllable that is not A; Experiment 2), AA(A)(A)¬A (two-to-four times the syllable A and one final syllable that is not A; Experiment 3). Representing the structures in Experiments 2-3 requires a form of negation. Results suggest that infants are able to compute both identity and negation. More generally, these results lend credit to the hypothesis that the infant mind is equipped with rudimentary logical operators before language takes off.