A recently accepted paper in JOURNAL OF COGNITIVE NEUROSCIENCE

Authors: Jon Andoni Duñabeitia, Maria Dimitropoulou, Jonathan Grainger, Juan Andrés Hernández and Manuel Carreiras.

Title: Differential sensitivity of letters, numbers and symbols to character transpositions.


Abstract:
The present study was designed to explore whether the human visual system has different degrees of tolerance to character position changes for letter strings, digit strings and symbol strings. An explicit perceptual matching task was used (same-different judgment), and participants’ electrophysiological activity was recorded. Materials included trials in which the referent stimulus and the target stimulus were identical, or differed either by two character replacements, or by transposing two characters. Behavioral results showed clear differences in the magnitude of the transposed-character effect for letters as compared to digit and symbol strings. Electrophysiological data confirmed this observation, showing an N2 character-transposition effect that was only present for letter strings. An earlier N1 transposition effect was also found for letters, but was absent for symbols and digits, while a later P3 effect was found for all types of string. These results provide evidence for a position coding mechanism that is specific to letter strings, that was most prominent in an epoch between 200 and 325 milliseconds, and that operates in addition to more general-purpose position coding mechanisms.


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