Abstract
Two studies of 4-yr.-old Ss were concerned with the effects of mode of presentation (simultaneous versus successive) and number of categories on estimates of proportion. Exp. I compared simultaneous and successive presentations, using two categories of elements. The results indicate that 4-yr.-old children are fairly accurate in their estimates and are able consistently to discriminate proportions differing by .20 but are unable to differentiate those differing by .10. These results replicate fairly well an earlier study by Ginsburg (1967). There was no significant difference in estimates of proportion as a result of mode of presentation. In Exp. II the 13 4-yr.-old children performed at about a chance level on a 3-category simultaneous task.