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Abstract:
Abstract: People are faster in recognizing object or words
(targets) if these stimuli are preceded by semantically related
items when compared to unrelated items (primes), a phenomenon
called "semantic priming". Recent findings have showed that
semantic priming can also occur in the absence of overt
identification of the prime (Dehaene et al., 1998). In the present
study we employed Event Related Potentials (ERPs) to assess whether
semantic priming in these two conditions rely on similar or
different neural systems (Pratarelli et al., 1989) by manipulating
the semantic relationship between pairs of English words in two
lexical decision tasks. Targets were preceded by primes that were
either semantically related (cat-DOG) or unrelated (pen-DOG). In
the masked condition, primes were briefly flashed (66 msec) before
the targets (500 msec) and preceded by a mask that prevented their
identification. In the unmasked condition, both primes and targets
were presented for 500 msec. Behavioral evidence for semantic
priming was found in both tasks. Consistent with many previous
studies, ERPs in the unmasked condition were more negative to
unrelated than related words starting 300 msec after the
presentation of the targets (N400). In the masked condition, ERPs
showed a similar but smaller N400 effect. In addition, there were
earlier (150 msec) differences between related and unrelated words
over temporal and frontal sites, suggesting that different neural
systems mediate semantic priming with and without awareness.
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