Goffin's cockatoos, a kind of small parrot native to Australasia, have been shown to have similar shape-recognition abilities to a human two-year-old. Though not known to use tools in the wild, the birds have proved skilful at tool use while kept in the cage. In a recent experiment, cockatoos were presented with a box with a nut inside it. The clear front of the box had a "keyhole" in a geometric shape, and the birds were given five differently shaped "keys" to choose from. Inserting the correct "key" would let out the nut.

In humans, babies can put a round shape in a round hole from around one year of age, but it will be another year before they are able to do the same with less symmetrical（对称的） shapes. his ability to recognize that a shape will need to be turned in a specific direction before it will fit is called an "allocentric frame of reference". In the experiment, Goffin's cockatoos were able to select the right tool for the job, in most cases, by visual recognition alone. Where trial-and-error was used, the cockatoos did better than monkeys in similar tests. This indicates that Goffin's cockatoos do indeed possess an allocentric frame of reference when moving objects in space, similar to two-year-old babies.

The next step, according to the researchers, is to try and work out whether the cockatoos rely entirely on visual clues（线索）, or also use a sense of touch in making their shape selections.

    Before the 1830s, most newspapers were sold through annual subscriptions in America, usually $8 to $10 a year. Today $8 or $10 seems a small amount of money, but at that time these amounts were forbidding to most citizens. Accordingly, newspapers were read almost only by rich people in politics or the trades. In addition, most newspapers had little in them that would appeal to a mass audience. They were dull and visually forbidding. But the revolution that was taking place in the 1830s would change all that.

    The trend, then, was toward the "penny paper"-a term referring to papers made widely available to the public. It meant any inexpensive newspaper; perhaps more importantly it meant newspapers that could be bought in single copies on the street.

    This development did not take place overnight. It had been possible(but not easy)to buy single copies of newspapers before 1830,but this usually meant the reader had to go down to the printer's office to purchase a copy. Street sales were almost unknown. However, within a few years, street sales of newspapers would be commonplace in eastern cities. At first the price of single copies was seldom a penny-usually two or three cents was charged-and some of the older well-known papers charged five or six cents. But the phrase "penny paper" caught the public's fancy, and soon there would be papers that did indeed sell for only a penny.

    This new trend of newspapers for "the man on the street" did not begin well. Some of the early ventures(企业)were immediate failures. Publishers already in business, people who were owners of successful papers, had little desire to change the tradition. It took a few youthful and daring businessmen to get the ball rolling.

    Monkeys seem to have a way with numbers.

    A team of researchers trained three Rhesus monkeys to associate 26 clearly different symbols consisting of numbers and selective letters with 0-25 drops of water or juice as a reward. The researchers then tested how the monkeys combined—or added—the symbols to get the reward.

    Here's how Harvard Medical School scientist Margaret Livingstone, who led the team, described the experiment: In their cages the monkeys were provided with touch screens. On one part of the screen, a symbol would appear, and on the other side two symbols inside a circle were shown. For example, the number 7 would flash on one side of the screen and the other end would have 9 and 8. If the monkeys touched the left side of the screen they would be rewarded with seven drops of water or juice; if they went for the circle, they would be rewarded with the sum of the numbers—17 in this example.

    After running hundreds of tests, the researchers noted that the monkeys would go for the higher values more than half the time, indicating that they were performing a calculation, not just memorizing the value of each combination.

    When the team examined the results of the experiment more closely, they noticed that the monkeys tended to underestimate（低估）a sum compared with a single symbol when the two were close in value—sometimes choosing, for example, a 13 over the sum of 8 and 6. The underestimation was systematic: When adding two numbers, the monkeys always paid attention to the larger of the two, and then added only a fraction（小部分）of the smaller number to it.

    "This indicates that there is a certain way quantity is represented in their brains, "Dr. Livingstone says. "But in this experiment what they're doing is paying more attention to the big number than the little one.”