An ERP investigation of the modulation of subliminal priming by exogenous cues.

Marzouki, Grainger, and Theeuwes [Marzouki, Y., Grainger, J., and Theeuwes, J. 2007. Exogenous spatial cueing modulates subliminal priming. Acta Psychol. 126, 34-45.] demonstrated that masked repetition priming of letter identification is affected by the allocation of spatial attention to the prime location by an exogenous cue. Behavioral priming effects were obtained only when the exogenous cue was valid (prime at the same location as the cue). The present ERP study provides a further investigation of such exogenous influences on masked priming. Results showed a significant modulation of the amplitude of the P3 ERP component generated by centrally located target letters as a function of repetition priming and cue validity. The amplitude difference between repetition and unrelated primes was found to be enhanced in the presence of a valid exogenous cue. The electrophysiological data therefore confirm the influence of exogenous cues on the processing of subliminally presented prime stimuli, and show that such effects can be obtained in the absence of eye movements. The results further point to a relatively late influence of prime stimuli on target processing when these stimuli occupy distinct locations.