In the 1950s, the pioneers of artificial intelligence (AI) predicted that, by the end of this century, computers would be conversing with us at work and robots would be performing our housework. But as useful as computers are, they're nowhere close to achieving anything remotely resembling these early aspirations for humanlike behavior. Never mind something as complex as conversation: the most powerful computers struggle to reliably recognize the shape of an object, the most elementary of tasks for a ten-month-old kid.

　　A growing group of AI researchers think they know where the field went wrong. The problem, the scientists say, is that AI has been trying to separate the highest, most abstract levels of thought, like language and mathematics, and to duplicate them with logical, step-by-step programs. A new movement in AI, on the other hand, takes a closer look at the more roundabout way in which nature came up with intelligence. Many of these researchers study evolution and natural adaptation instead of formal logic and conventional computer programs. Rather than digital computers and transistors, some want to work with brain cells and proteins. The results of these early efforts are as promising as they are peculiar, and the new nature-based AI movement is slowly but surely moving to the forefront of the field.

　　Imitating the brain's neural (神经的) network is a huge step in the right direction, says computer scientist and biophysicist Michael Conrad, but it still misses an important aspect of natural intelligence. "People tend to treat the brain as if it were made up of color-coded transistors", he explains, "but it's not simply a clever network of switches. There are lots of important things going on  inside the brain cells themselves." Specifically, Conrad believes that many of the brain's capabilities stem from the pattern recognition proficiency of the individual molecules that make up each brain cell. The best way to build and artificially intelligent device, he claims, would be to build it around the same sort of molecular skills.

　　Right now, the notion that conventional computers and software are fundamentally incapable of matching the processes that take place in the brain remains controversial. But if it proves true, then the efforts of Conrad and his fellow AI rebels could turn out to be the only game in town.

11. A new study on birds' sleep has revealed that ____________.

 A) half-brain sleep is found in a wide variety of birds

 B) half-brain sleep is characterized by slow brain waves

 C) birds can control their half-brain sleep consciously

 D) birds seldom sleep with the whole of their brain at rest

12. According to the passage, birds often half sleep because ______________.

 A) they have to watch out for possible attacks

 B) their brain hemisphere take turns to rest 跨段

 C) the two halves of their brain are differently structured 没

 D) they have to constantly keep an eye on their companions 反

13. The example of a bird sleeping in front of a mirror indicates that _____________.

 A) the phenomenon of birds dozing in pairs is widespread

 B) birds prefer to sleep in pairs for the sake of security

 C) even an imagined companion gives the bird a sense of security

 D) a single pet bird enjoys seeing its own reflection in the mirror

14. While sleeping, some water mammals tend to keep half awake in order to __________.

 A) alert themselves to the approaching enemy

 B) emerge from water now and then to breathe

 C) be sensitive to the ever-changing environment

 D) avoid being swept away by rapid currents

15. By "just the tip of the iceberg" (Line 2, Para.8), Siegel suggests that ____________.

 A) half-brain sleep has something to do with icy weather

 B) the mystery of half-brain sleep is close to being solved

 C) most birds living in cold regions tend to be half sleepers