Story of Psychology - Morton Hunt [346]
Tardy students annoy inexperienced teachers.
But they fared badly with nonsensical sentences of the same length, like:
Purple concrete trained imaginative alleys.37
A number of studies showed that we easily retain the message of a sentence in short-term memory but swiftly forget its exact words. Similarly, we retain in long-term memory for months, years, or a lifetime the content or meaning of some conversations we have had and books we have read, the gist of courses we have taken, and innumerable facts we have learned, but none, or at most a few, of the exact words in which any of these were couched. The mass of material stored away in this fashion is far larger than most of us can imagine: John Griffith, a mathematician, calculated that the lifetime capacity of the average human memory is up to 1011 (one hundred trillion) bits,* or five hundred times as much information as is contained in the Encyclopaedia Britannica. 38
New information in short-term memory is forgotten after we use it, unless we make it part of long-term memory by subjecting it to further processing. One form of processing is rote memorizing, as schoolchildren memorize multiplication tables. Another is the linking of new information to some easily remembered structure or mnemonic device, like a singsong jingle (the preschool alphabet song) or a rhyming rule (“When the letter C you spy, / Put the E before the I”).
But a far more important kind, as became clear in the research performed in the 1960s and 1970s, is “elaborative processing,” in which the new information is connected to parts of our existing organized mass of long-term memories. We splice it into our semantic network, so to speak. If the new item is a mango and we have never seen one before, we link the word and concept to the appropriate part of long-term memory (not a physical location—ideas and images are now thought to be scattered throughout the brain—but a conceptual one: the category “fruit”), along with the mango’s visual image, feel, taste, and smell (each of which we also link to the categories of images, tactile qualities, and so on), plus what we learn about where it grows, what it costs, how to serve it, and more. In the future, when we try to think of a mango, we retrieve the memory in any one of many ways: by recalling its name, or thinking about fruit, or about fruit with a green skin, or about yellow sweet slices, or any other category or trait with which it is linked.
Much of what was learned about how all these kinds of information are organized was the product of reaction-time experiments such as asking subjects to name, in a brief period of time, as many things as they can that are red, or that are fruit, or that start with a given letter. Using that technique, Elizabeth Loftus found that in one minute volunteers could, on average, name twelve instances of “bird” but only nine of “yellow.” Her conclusion was that we cannot readily look directly in memory for examples of a property but instead locate categories of objects (birds, fruit, vegetables), and scan each for that property.39
Similarly, as Loftus and a colleague, Allan Collins, found, it takes people longer to answer “true” or “false” to the statement “An ostrich is a bird” than to the statement “A canary is a bird.” The implication: A canary is a more typical bird than an ostrich, is closer to the center of the category, so it requires less time to identify. Collins and Loftus, on the basis of such data, symbolically portrayed long-term semantic memory as an intricate network that is hierarchical (a general category is surrounded by specific instances) and associative (each instance is linked to a number of traits). They