Correlation between prime duration and semantic priming effect: evidence from N400 effect.

When the prime word is masked and flashed very quickly, its presence cannot be perceived by the subjects, but it can still accelerate the processing of the subsequent relevant target stimulus. This is known as the masked priming effect. Adopting a similar experimental paradigm, in this study we take the gray scale pictures describing ordinary objects as prime stimuli and the environmental sounds as target stimuli. The subjects are then asked to classify the target sounds to investigate whether incongruent target sounds elicit the N400 semantic priming effect. At the same time, the prime-mask withdraw value is made at these time intervals: 16ms, 33ms, 50ms, 66ms and 83ms, so as to reveal whether there exists a correlation between the prime duration and the priming effect. The result shows that, at each time interval, the processing of sounds that are congruent with prime pictures is sped up and sounds that are incongruent with prime pictures trigger the N400 effect. The amplitude of the N400 effect is enlarged proportionally with the time interval and gradually approaches the point of saturation. Given this, it is believed that the N400 effect reflects automatic semantic processing, that consciousness is not a prerequisite of semantic priming, and that early visual information has an accumulative priming effect on target sounds.