THE most used IQ tests do not provide just a single figure as a measure of ability but have at least two (and usually more) scores. For instance, the IQ test most commonly used by psychologists is the WISC (Wechsler Intelligence Scales for Children). This has two main IQ figures, currently called index score: a verbal comprehension index (or verbal IQ) and a perceptual reasoning index (or nonverbal IQ). The verbal index or IQ is a measure of spoken language ability; the score shows how the child performed on tests of vocabulary and verbal reasoning. The nonverbal index or IQ is a measure of visual-spatial ability; here the score shows how the child performed on puzzle- and pattern-based tests. The two IQ scores may be combined to give an overal indication of ability, called general or full scale IQ.
At the request of several families he and Mrs Legge gave a home for some months to a young Dutch girl, a granddaughter of the first Dutch governor of the Straits Settlements. She had several pearls of which the Dutch residents were great collectors, got from oysters found in a river of the Malay Peninsula, when she left them she gave Mrs Legge a small box containing a large pearl the size of a pea, with a blue spot on it, and two others not so large. This box was then put away and locked up. Several weeks later he took it out and on opening it discovered more than a dozen pearls, most of them very small. Astonished at the phenomenon he called his chief servant, a Portuguese, who happened to enter the room and who expressed no surprise but declared it to be a common occurrence. On enquiry he found that many of the Dutch people had jars of pearls, large and small, which had accumulated in this way. Some years later he related the incident at dinner on board ship. The captain was a cautio