Final answer:
Studies on inattentional blindness and split-brain conditions provide knowledge about unconscious processing of stimuli. Double simultaneous stimulation and functional imaging are key methods used in these studies. They demonstrate how patients might process stimuli without conscious awareness due to attention focus or hemisphere disconnection.
Step-by-step explanation:
Studies into phenomena such as inattentional blindness and the effects of split-brain surgeries have provided insights into how patients may process stimuli without being consciously aware of them. Tests like double simultaneous stimulation, where similar stimuli are applied to both sides of the body, can reveal if a patient perceives stimuli on one side only, suggesting potential damage to the contralateral posterior parietal lobe. In split-brain patients, due to the sectioning of the corpus callosum to treat severe epilepsy, each hemisphere of the brain can possess unique functions. For example, such patients might be able to pick up an object with their left hand (controlled by the right hemisphere) while not being able to verbally identify it, as the speech center is typically on the left side of the brain.
Functional imaging studies, measuring changes in blood flow to active brain regions during tasks, provide further evidence on how the brain processes visual information even when subjects do not consciously register seeing certain stimuli.