Increasing interletter spacing facilitates encoding of words.

Recent research has suggested that words presented with a slightly increased interletter spacing are identified faster than words presented with the default spacing settings (i.e., casino is faster to identify than casino; see Perea, Moret-Tatay, & Gomez, 2011). To examine the nature of the effect of interletter spacing in visual-word recognition (i.e., affecting encoding processes vs. quality of information), we fitted Ratcliff's (1978) diffusion model to a lexical decision experiment in which we manipulated a range of five interletter spacings (from condensed [-0.5] to expanded [1.5]). The results showed an effect of interletter spacing on latencies to word stimuli, which reflected a linear decreasing trend: Words presented with a more expanded interletter spacing were identified more rapidly than those with a narrower spacing. Fits from the diffusion model revealed that interletter spacing produces small changes in the encoding process rather than changes in the quality of lexical information. This finding opens a new window of opportunities to examine the role of interletter spacing in more applied settings.