Eye movements while reading and searching spatially transformed text: A developmental examination.

The effects of spatial manipulation on eye movement when subjects either read or searched through paragraphs were examined. Adults, third, and fifth graders were presented with paragraphs which were typed normally or in alternating case (upper and lower). The spacing between the words was either normal, filled, or absent. The results show that approximately twice as many character spaces are processed during search as during reading. Subjects made more fixations of shorter duration during search than reading. The data indicated that the ability to vary the size of the perceptual unit develops with experience. When spatial cues were unavailable, all subjects resorted to a letter-by-letter-like processing strategy in reading but not in search. Although reading and search were found to be sensitive to the same types of spatial manipulations, discrepancies of span and speed suggest qualitative differences; comprehension demands during reading can account for these differences. The data were interpreted to provide support for the two-stage model of Hochberg (1970).