The search for an input-coding scheme: transposed-letter priming in Arabic.

Two key issues for models of visual word recognition are the specification of an input-coding scheme and whether these input-coding schemes vary across orthographies. Here, we report two masked-priming lexical decision experiments that examined whether the ordering of the root letters plays a key role in producing transposed-letter effects in Arabic--a language characterized by non-concatenative morphology. In Experiment 1, letter transpositions involved two letters from the root, whereas in Experiment 2, letter transpositions involved one letter from the root and one letter from the word pattern. Results showed a reliable transposed-letter priming effect when the ordering of the letters of the root was kept intact (Experiment 2), but not when two root letters were transposed (Experiment 1). These findings support the view that the order of the root letters is allowed only a minimum degree of perceptual noise to avoid the negative impact of activating the "wrong" root family.