The effect of attention on developmental differences in inspection time

Inspection time (IT), an estimate of the speed of perceptual encoding, has been shown to relate to IQ in adults and to differences in mental age in children. This paper investigates the possibility that older children have faster ITs because of improvements in attentional factors related to task performance rather than because of any age differences in processing speed. Attentional factors were manipulated in two ways. First the IT task was either self, or externally, paced. The hypothesis was that allowing the children to pace themselves should reduce the influence of distractibility on performance and reduce any age difference in IT. Second, the IT stimulus was presented after either a fixed, or a random, foreperiod. The hypothesis was that any advantage the older children have in involuntary attentional processes would be removed when the foreperiod was random, again reducing the age difference in IT. Seventy-two Ss. 40 12-yr-olds and 32 8-yr-olds, were given the task in one of four conditions, self or externally paced, with a fixed or random, foreperiod, and measures of IT were taken. There was an effect of age on one of the IT measures but it did not interact with any of the attentional variables. The random foreperiod produced significantly longer ITs in the externally paced condition. The normally robust relationship between MA, IQ and IT was either weak or absent in the data. The conclusion is that are attentional influences on IT performance but they detract from, rather than induce, the relationship between IT, age and intelligence. © 1989