Subjects at three grade levels, third, sixth, and college (8, 11, and 20 years of age, respectively), were asked to identify briefly presented words accompanied by either words or letter strings in the same or opposite hemifield. Results indicated two sources of visual field interference, one relating to the presence of alphanumeric information elsewhere in the visual field and the second concerning the meaningfulness (lexical identity) of that information. The former showed a decrease in importance with age, and the latter an increase. Results were discussed in terms of the development of selective attention and hemispheric interaction.