Parallel processing of written words as a function of visual field position

Reading places intense demands on the visual system. Although many words on a page are visible at once, it is debated whether readers fully process multiple words in parallel, or focus attention on one word at a time. We have used a dual-task paradigm to investigate whether it is even possible to recognize two words simultaneously. In these experiments, participants view pairs of English words that are flashed briefly and replaced by post-masks at an interval set to each participant’s threshold. This gives them just enough time to recognize one word with focused attention. The question is: can they recognize two words with divided attention in that same amount of time? We previously found that the answer was no: accuracy in the divided attention condition was so impaired that it supported a serial model. In those studies, the words were positioned either just above and below fixation, or to the left and right, centered at 2.75º (~4 letter spaces). Here, we report multiple experiments in which we investigate whether parallel processing of two words is possible when they are arranged more like in natural reading. By varying the words’ eccentricities and lengths, we have found that for many observers (but not all), accuracy rises above the serial model’s prediction when the words do not extend more than ~6 letter spaces from the fovea. Performance is most consistent with parallel processing when one word is directly fixated and the other is placed to the right. Altogether, this study supports the hypothesis that two words can be recognized in parallel as long as they are arranged horizontally and fit within a narrow window around the point of gaze fixation. Further research will examine the nature of individual differences in this processing capacity.