Not many people can get through to 32-year-old David. His clear, green eyes flick past the group of people talking about him without any apparent recognition and roam over the sunny sea beyond them.
More severely autistic than the character played by Dustin Hoffman in "Rain Man," David cannot speak, dress or eat by himself and sometimes has uncontrollable fits of rage.But a group of psychiatrists is trying to prove that dolphins can reach him when most humans cannot.
Every month, they bring David and other severely autistic patients from Jerusalem down to the Red Sea resort of Eilat to swim among dolphins and feed them at the enclosed Dolphin Reef in an experimental therapy.
"Our patients are having a very good contact with the dolphins," said Daniel Meir, director of a wing for autism sufferers.
"We see a marked improvement in their behavior after they come here to swim with the dolphins. They communicate more with us; they cry and mutilate themselves less. I am putting together the evidence to take to conferences."
The possible therapeutic powers of dolphins have aroused interest across the world. Researchers held a conference in Belgium earlier this year on man's relationship with the aquatic mammal and in Japan a "Dolphin Healing Center" has opened to treat all kinds of mental illnesses and depression.
In this Israeli resort town, David slaps the water happily as some of the eight dolphins swim round him. He reaches out to touch them as they swim past and throws fish in their mouth at feeding times.
Marie Steurer, a dolphin trainer who has worked with groups suffering various mental handicaps for two years, says the dolphins, brought from the Black Sea three years ago, are highly sensitive to different human character types.
"They definitely recognize when someone is handicapped. They swim slower and are less boisterous than with the trainers. They know when someone needs help. They look for the patient and seek him out," she said.