Abstract
Word reading speed in peripheral vision is slower when words are in close proximity of other words (Chung, 2004). This word crowding effect could arise as a consequence of interaction of low-level letter features between words, or the interaction between high-level holistic representations of words. We evaluated these two competing hypotheses by examining how word crowding changes for five configurations of flanking words: the control condition – flanking words were oriented upright; vertical-flip – each flanking word was the up-down mirror-image of the original; horizontal-flip – each flanking word was the left-right mirror-image of the original; letter-flip – each letter of the flanking word was the left-right mirror-image of the original; and scrambled – letters in each flanking word were scrambled in order. The low-level feature interaction hypothesis predicts similar word crowding effect for all the different flanker configurations, while the high-level representation hypothesis predicts less word crowding effect for all the alternative flanker conditions, compared with the control condition. Six young adults read sequences of six random four-letter words presented one at a time, using the rapid serial visual presentation paradigm. Words (2° print size) were presented at 10° in the nasal field of the left eye of each observer. For each flanker configuration, reading speed was determined when the target words were presented alone, or flanked above or below by other words at one of four vertical word spacings (0.7×, 1×, 1.5×, and 2× standard line spacing). Across observers, the reading speed vs. spacing functions were very similar for all flanker configurations. Reading speed was unaffected by flankers until the word spacing was reduced to 0.7× (p<0.0005) when reading speed dropped by an average of 34%, compared with the unflanked reading speed. The remarkably similar word crowding effect irrespective of the flanker configurations suggest that word crowding arises as a consequence of interaction of low-level letter features.
Supported by NIH grants T35-EY007139 and R01-EY012810.