Position-specific effects within the SERIOL framework of letter-position coding

Abstract

In the SERIOL (sequential encoding regulated by inputs to oscillations within letter units) framework, letter position within a word is encoded by the temporal firing pattern of letter units. As opposed to channel-specific schemes, a letter unit can potentially represent any position. This lack of positional specificity is consistent with studies showing that priming can occur across different positions within a letter string (Grainger and Jacobs 1991, European Journal of Cognitive Psychology, 3:413-434, Peressotti and Grainger 1995, Perception of Psychophysics, 57: 875-890). However, these studies also showed that same-position priming is more robust than this cross-position priming. This result seems inconsistent with non-position-specific letter units. Here we give an explanation of these results under the SERIOL framework. Using mathematical models, we show that broadly tuned feature detectors and an activational gradient can account for the complex experimental data on position-specific and cross-position letter priming.