Skip to main content Accessibility help

Does Extra Interletter Spacing Help Text Reading in Skilled Adult Readers?

  • Manuel Perea (a1), Lourdes Giner (a1), Ana Marcet (a1) and Pablo Gomez (a2)


A number of experiments have shown that, in skilled adult readers, a small increase in interletter spacing speeds up the process of visual word recognition relative to the default settings (i.e., judge faster than judge). The goal of the present experiment was to examine whether this effect can be generalized to a more ecological scenario: text reading. Each participant read two stories (367 words each) taken from a standardized reading test. The stories were presented with the standard interletter spacing or with a small increase in interletter spacing (+1.2 points to default) in a within-subject design. An eyetracker was used to register the participants’ eye movements. Comprehension scores were also examined. Results showed that, on average, fixation durations were shorter while reading the text with extra spacing than while reading the text with the default settings (237 vs. 245 ms, respectively; η2 =. 41, p = .01). However, the number of fixations (while nonsignificant) was slightly higher in the text with extra spacing than in the text with the default spacing, and cancelled out the effect of interletter spacing in total reading times (F < 1). Comprehension scores were similar in the two spacing conditions (F < 1). Thus, at least for skilled adult readers, interletter spacing does not seem to play a consistently facilitative role during text reading.


Corresponding author

*Correspondence concerning this article should be addressed to Manuel Perea. Universitat de València. Metodología. Valencia (Spain). E-mail:


Hide All
Bouma, H. (1970). Interaction effects in parafoveal letter recognition. Nature, 226, 177178.
Chung, S. T. L. (2002). The effect of letter spacing on reading speed in central and peripheral vision. Investigative Ophthalmology & Visual Science, 43, 12701276.
Engbert, R., Nuthmann, A., Richter, E. M., & Reinhold, K. (2005). SWIFT: A dynamical model of saccade generation during reading. Psychological Review, 112, 777813.
Facoetti, A., Corradi, N., Ruffino, M., Gori, S., & Zorzi, M. (2010). Visual spatial attention and speech segmentation are both impaired in preschoolers at familial risk for developmental dyslexia. Dyslexia, 16, 226239.
Franceschini, S., Gori, S., Ruffino, M., Pedrolli, K., & Facoetti, A. (2012). A causal link between visual spatial attention and reading acquisition. Current Biology, 22, 814819.
Franceschini, S., Gori, S., Ruffino, M., Viola, S., Molteni, M., & Facoetti, A., (2013). Action video games make dyslexic children read better. Current Biology, 23, 462466.
Gomez, P., & Perea, M. (2014). Decomposing encoding and decisional components in visual-word recognition: A diffusion model analysis. The Quarterly Journal of Experimental Psychology, 67, 24552466.
Gori, S., Cecchini, P., Bigoni, A., Molteni, M., & Facoetti, A. (2014). Magnocellular-dorsal pathway and sub-lexical route in developmental dyslexia. Frontiers in Human Neuroscience, 8, 460.
Gori, S., Mascheretti, S., Giora, E., Ronconi, L., Ruffino, M., Quadrelli, E., ... Marino, C. (2015). The DCDC2 intron 2 deletion impairs illusory motion perception unveiling the selective role of magnocellular-dorsal stream in reading (dis)ability. Cerebral Cortex, 25, 16851695.
Gori, S., & Facoetti, A. (2014). Perceptual learning as a possible new approach for remediation and prevention of developmental dyslexia. Vision Research, 99, 7887.
Gori, S., & Facoetti, A. (2015). How the visual aspects can be crucial in reading acquisition? The intriguing case of crowding and developmental dyslexia. Journal of Vision, 15, 8.
Jeffreys, H. (1961).Theory of probability. Oxford, UK: Oxford University Press
Martínez, T., Vidal-Abarca, E., Sellés, P., & Gilabert, R. (2008). Evaluación de las estrategias y los procesos de comprensión: El test de procesos de comprensión (TPC) [Evaluation of comprehension strategies and processes: Test of Comprehension Processes]. Infancia y Aprendizaje: Journal for the Study of Education and Development, 31, 319332.
McCandliss, B. D. (2012). Helping dyslexic children attend to letters within visual word forms. Proceedings of the National Academy of Science of the United States of America, 109, 1106411065.
McLeish, E. (2007). A study of the effect of letter spacing on the reading speed of young readers with low vision. British Journal of Visual Impairment, 25,133143.
Montani, V., Facoetti, A., & Zorzi, M. (2015). The effect of decreased interletter spacing on orthographic processing. Psychonomic Bulletin & Review, 22, 824832.
Moores, E., Cassim, R., & Talcott, J. B. (2011). Adults with dyslexia exhibit large effects of crowding, increased dependence on cues, and detrimental effects of distracters in visual search tasks. Neuropsychologia, 49, 38813890.
Perea, M., & Gomez, P. (2012a). Increasing interletter spacing facilitates encoding of words. Psychonomic Bulletin and Review, 19, 332338.
Perea, M., & Gomez, P. (2012b). Subtle increases in interletter spacing facilitate the encoding of words during normal reading. PLOS ONE, 7, e47568.
Perea, M., Moret-Tatay, C., & Gomez, P. (2011). The effects of interletter spacing in visual-word recognition. Acta Psychologica, 137, 345351.
Perea, M., Panadero, V., Moret-Tatay, C., & Gomez, P. (2012). The effects of inter-letter spacing in visual-word recognition: Evidence with young normal readers and developmental dyslexics. Learning and Instruction, 22, 420430.
Ratcliff, R., Gomez, P., & McKoon, G. (2004). A diffusion model account of the lexical decision task. Psychological Review, 111, 159182.
Reichle, E. D., Pollatsek, A., Fisher, D. L., & Rayner, K. (1998). Toward a model of eye movement control in reading. Psychological Review, 105, 125157.
Risko, E. F., Lanthier, S. N., & Besner, D. (2011). Basic processes in reading: The effect of interletter spacing. Journal of Experimental Psychology: Learning, Memory, and Cognition, 37, 14491457.
Rouder, J. N., Speckman, P. L., Sun, D., Morey, R. D., & Iverson, G. (2009). Bayesian t tests for accepting and rejecting the null hypothesis. Psychonomic Bulletin & Review, 16, 225237.
Schneps, M. H., Thomson, J. M., Chen, C., Sonnert, G., & Pomplun, M. (2013). E-readers are more effective than paper for some with dyslexia. PLoS ONE, 18, e75634
Schneps, M. H., Thomson, J. M., Sonnert, G., Pomplun, M., Chen, C., & Heffner-Wong, A. (2013). Shorter lines facilitate reading in those who struggle. PLoS ONE, 5, e71161
Slattery, T. J., & Rayner, K. (2013). Effects of intraword and interword spacing on eye movements during reading: Exploring the optimal use of space in a line of text. Attention, Perception, & Psychophysics, 75, 12751292.
Spinelli, D., de Luca, M., Judica, A., & Zoccolotti, P. (2002). Crowding effects on word identification in developmental dyslexia. Cortex, 38, 179200.
Stein, J., & Walsh, V. (1997). To see but not to read; the magnocellular theory of dyslexia. Trends in Neurosciences, 20, 147152.
Tai, Y. C., Sheedy, J., & Hayes, J. (2009, June). The effect of interletter spacing on reading. Paper presented at the Computer Displays & Vision conference. Forest Grove, OR.
van den Boer, M., & Hakvoort, B. E. (2015). Default spacing is the optimal spacing for word reading. The Quarterly Journal of Experimental Psychology, 68, 697709.
Vidyasagar, T. R., & Pammer, K. (2010). Dyslexia: A deficit in visuo-spatial attention, not in phonological processing. Trends in Cognitive Sciences, 14, 5763.
Vinckier, F., Qiao, E., Pallier, C., Dehaene, S., & Cohen, L. (2011). The impact of letter spacing on reading: A test of the bigram coding hypothesis. Journal of Vision, 11, 8.
Zorzi, M., Barbiero, C., Facoetti, A., Lonciari, I., Carrozzi, M., Montico, M., ... Ziegler, J. C. (2012). Extra-large letter spacing improves reading in dyslexia. Proceedings of the National Academy of Sciences, 109, 1145511459.


Does Extra Interletter Spacing Help Text Reading in Skilled Adult Readers?

  • Manuel Perea (a1), Lourdes Giner (a1), Ana Marcet (a1) and Pablo Gomez (a2)


Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed