Kahneman and Treisman (1984, p.55) have succinctly described the main disagreement between early selection and late selection theories of attention: 'The classic question of attention theory has always been whether attention controls the build-up of perceptual information, or merely selects among the responses associated with currently active percepts.' Early selection theories hold that attention serves to select which one of a number of stimuli will be further semantically processed and stored in long term memory. On the other hand, more recent late selection theories maintain that selective attention operates after