New information inhibits the emergence and awareness of previously processed information.
If the new input is decreased or impaired while awareness remains, stored images may be released and experienced as hallucinations or dreams. In one study conducted at McGill University in Montreal by psychologist Donald Hebb, student volunteers experienced what we call childish emotional responses and hallucinations after twenty-four hours. But he also found that it was lost no longer than two days after the experimental conditions were terminated, if gains were not consolidated thereafter. Vernon explains that the brainstem reticular formation acts as a way station for all messages coming in and going out of the brain. Normally it inhibits some messages and enhances others, thus dictating which ones get paid conscious attention.