Abstract
The idea that attentional selection is carried out by means of facilitatory as well as inhibitory mechanisms has gained support in the past few years. With the aim of studying the influence of these mechanisms in language processing, we have used the semantic priming experimental procedure with a parafoveal presentation of two words in the prime display. One of the prime words was to be attended to (attended prime) and the other was to be ignored (distractor). Participants responded with a lexical decision task on the subsequent probe word. In the first experiment we manipulated the SOA between prime and probe at four levels: 250, 450, 650 and 850 ms. At all the SOA levels, we obtained facilitatory effects for probes related to the attended primes. However, inhibitory effects for probes related to ignored primes were only obtained with SOAs of 450, 650 and 850 ms. The facilitatory and inhibitory effects with an SOA of 850 ms were replicated with different experimental conditions in Experiments 2 and 3. The absence of negative priming in the 250 ms SOA supports the idea that the inhibitory mechanism is linked to a controlled and strategic processing. The attentional facilitation, however, can be produced either in an automatic or a controlled way. Moreover, we observed a consistent pattern of lateralization of the effects of facilitation and inhibition, given that the mentioned effects were only produced for primes presented in the right visual field. This pattern of lateralization is discussed in relation to the functional differences between the right and left hemispheres regarding semantic processing. Key words: Semantic priming, semantic negative priming, time-course, attentional modulation, lateralization.