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Abstract:
Last year we reported that a mismatch between the intrinsic
and deictic reference frames caused a significant negative wave
peaking at 325 ms. One explanation for this effect is that it
represents a difference in the N400 component, however, the N400
typically has a peak latency of 400 ms. The N400 may have been
earlier because there was a restricted range of possible
prime/target pairings. In the current study, we tested this
possibility using more typical N400 priming paradigms with a
restricted number of potential target stimuli. Sixteen subjects
participated in two tasks where they had to make Match/Mismatch
decisions to target words preceded by priming pictures. In task 1,
primes (e.g., a car) were displayed in one of three orientations
(front, left or right) and were followed by one of three target
words (left, front or right). In task 2, one of two types of
priming pictures (e.g., a hammer or elephant) were displayed and
followed by the words ANIMAL or TOOL. In both experiments, 50% of
targets matched and 50% mismatched the prime. As predicted, the
contrast between match and mismatch targets produced a robust N400
effect 100 ms earlier than typical N400 paradigms. This lends
credence to the argument that the negativity we reported last year,
within a spatial processing framework, was also a member of this
family of ERPs.
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