Most people have been fooled by an optical illusion at some point. The Hermann Grid has people seeing gray shadows in what are actually pure white intersecting lines. The Ebbinghaus illusion tricks people into thinking that one circle is larger than another one, when they are actually the same size. In the past, studies have found that people with schizophrenia are immune to some optical illusions. The latest studies made in Germany and the UK have found that Schizophrenics are immune to the Hollow mask illusion. This illusion causes people to view a concave face as convex (it is seen as a normal face when it is actually sunk in). Scientists believe that Schizophrenics are not fooled by the illusion,”…because their brain disconnects ‘what the eyes see’ from what ‘the brain thinks it is seeing” (ScienceDaily). These two parts of the brain have difficulty communicating the “bottom-up” process where the eyes collect visual information and the “top-down” process where the information is interpreted to each other. This is known as dysconnectivity. The findings of the study also help explain why people that use cannabis are often immune to optical illusions when under the influence of the drug as well. Cannabis can make the two parts of the brain that collect and interpret information experience difficulty communicating. This is because THC, more commonly known as Cannabis, is a psychomimetic drug. The ingredient cannabis resin creates psychotic-like effects in its users. For this reason, the person experiences temporary dysconnectivity.