This essay is an extended version of the one published in the Star. Think of the last time you took a test. Psychologists are interested in the science of testing because tests attempt to measure, describe, and predict human traits.
Tests also make it possible to compare an individual with others.
Consequently, whether you are a superior student, a poor driver, or easily embarrassed, psychological tests provide us with an account of how we differ from one another. Put another way, tests provide us with knowledge of individual differences. Curiously, one could argue that the science of individual differences emerged not in some psychology laboratory but in an observatory in Greenwich England, over two centuries ago. Imagine it is 1794 and you are David Kinnebrook, a newly employed assistant to the prominent astronomer Nevil Maskelyne. Maskelyne requires you to record observations of stars and their locations.