The best controllers, they say, maintain a constantly moving mental picture of all their air traffic -- what they call situation awareness.

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And another question we're interested in is whether the animal actually has a mental picture of another dolphin when it hears a dolphin's signature whistle.

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Evelyn Bromet, professor of psychiatry at SUNY Stony Brook, says the study's real value may be in the picture of mental health that emerges over time.

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If Holmes was on medication, that may have made him appear more drowsy, making it more difficult to get a complete picture of his mental state, she said.

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When faced with an incomplete picture, the brain works to complete the mental image by inferring the missing information.

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