The placebo effect is improvement after a treatment with no active ingredient, driven by expectation. Its measured strength is modest, mostly for pain and nausea, and varies widely.
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No. Imaging, injury studies and metabolism show the whole brain is used. The 10 percent idea likely grew from self-help writing, and its exact origin is uncertain.
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Sleep is essential, but its core purpose is still unresolved. Several theories, likely overlapping, point to energy saving, bodily and brain restoration, and brain plasticity.
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It is the question of why physical processes in the brain come with subjective experience, a puzzle that explaining brain functions does not appear to settle.
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Researchers have no settled answer. Leading ideas link yawning to brain arousal and cooling, and contagious yawning to empathy, group synchrony and vigilance.
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Some brain functions do lean toward one hemisphere, but no evidence shows that people are overall left-brained or right-brained in personality or thinking style.
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Trainees spend years learning London's streets through map study, memory techniques and street visits. Those who qualified showed a gray matter increase in the posterior hippocampus.
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No single cause of déjà vu is settled. Leading explanations describe a memory-familiarity misfire, checked by the frontal cortex, or a resemblance to a forgotten scene.
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The binding problem asks how separate brain circuits processing different features produce one unified experience. It is really several distinct problems, and the experiential version remains unsolved.
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Split-brain studies showed that cutting the corpus callosum splits much perception, yet patients act like one person. Whether consciousness itself divides is unresolved.
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Blindsight is the ability of some people with damage to the primary visual cortex to detect or locate stimuli in their blind field without conscious seeing. Its cause and meaning are still debated.
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Libet found brain activity began hundreds of milliseconds before people reported the urge to move. Whether this undermines free will is disputed, and later work has weakened the inference.
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Integrated information theory says consciousness is a system's integrated cause-effect structure, measured as phi. It is controversial because critics call it untested and unfalsifiable, while defenders disagree.
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Anesthetics act on specific molecules such as the GABA receptor and alter brain circuits and rhythms. Exactly how this produces unconsciousness and amnesia is not fully settled.
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No. The five-sense list is a simplification dating to Aristotle. Experts agree there are more, but they disagree on the exact number because the definition of a sense is not settled.
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