Human performance effects cognitive abilities

Acute physical and psychological effects. Marijuana intoxication has an adverse effect on attention span, short-term memory, and psychomotor performance. Anxiety and panic attacks can occur, primarily in new users who are not familiar with marijuanas eflFects. At very high doses, some people experience delusions and hallucinations. There are no cases of fatal marijuana poisoning and humans are very unfikely to be able to ingest a fatal dose. The eflFect of marijuana intoxication impairs motor and cognitive abilities necessary to safely drive a car or operate machinery. The extent to which marijuana is involved in auto accidents is unclear. Many motorists intoxicated with marijuana drive more slowly and carefully and take fewer risks. However, there is an increased risk of accidents after using marijuana, but marijuana alone does not appear to contribute a great deal to accidents. Marijuana in combination with alcohol does. 

Planning errors arise from the basic human cognitive ability to solve problems. Human error in one situation is human ingenuity in another. Human problem solving rests on several unique human capabilities, one of which is the ability to create hypotheses and to test them and thus create new solutions to problems not previously considered. These hypotheses, however, may be wrong. Rasmussen has suggested that human error is often simply unsuccessful experiments in an unkind environment, where an unkind environment is defined as one in which it is not possible for the human to correct the effects of inappropriate variations in performance... 

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