Three experiments are reported which attempt to relate different information‐processing measures to individual differences in intelligence, and to developmental change. The first investigates Inspection Time (IT), a measure of the speed of sensory processing. The second and third investigate two aspects of memory processing; the rate of extraction of items from long‐term verbal memory (Posner&Mitchell, 1967) and the rate of scanning single items in short‐term memory (Sternberg, 1966). Measures of the variability of Reaction Times (RTs) are taken from the memory experiments. One hundred and fourteen children, ranging in age from 7–12, who attended a Surrey primary school, formed the subject pool. The experiments showed thatITis a special information‐processing measure, showing a different pattern of relationship with intelligence and development to that shown by the memory‐processing and RT variables. My conclusions are thatITreflects the efficiency of a basic processing mechanism, which is unchanging over the ages investigated, and that this efficiency may be unrelated to other basic cognitive mechanisms, such as memor