Part 1 of Essay
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 w ....

Part 2 of Essay
.... evidence on whether stimuli are semantically processed before or after selection is what people know about the unattended information. If the subject does not know the meaning of unattended information, this would mean that it has been discarded before it has been processed for meaning. One of the first approaches to this question was attempted by Cherry (1953, in Parkin, 1999) who carried out an experiment in which subjects were required hear two different messages simultaneously, one in each ear, but only pa ....