Alphabetical knowledge from whole words training: effects of explicit instruction and implicit experience on learning script segmentation

We investigated the possibility that pattern segmentation skills, specifically, phonological decoding, evolve implicitly in adult readers given training in an artificial script. In this Morse-like script each phoneme was represented by 2-3 discrete symbols. Subjects were trained in five consecutive sessions, on reading six nonsense words using a forced choice task that required translating symbol strings to sound patterns written in Latin letters. Three training conditions were compared within subject in terms of the time-course of learning and the ability to generalize the acquired knowledge (transfer): alphabetical whole words with letter decoding instruction (Explicit); alphabetical whole words (Implicit), and non-alphabetical whole words (Arbitrary). In separate blocks in each training session, a visual-matching task was administered using the same stimuli. Our results show: (a) that while all three training conditions were equally effective in terms of magnitude and time-course of learning accurate translation, each training condition resulted in a different type of knowledge (i.e. differential transfer). (b) Declarative knowledge of letters evolved from training on whole words only in subjects with previous experience in Explicit training. However, even with declarative knowledge of the specific letters subjects did not develop general letter segmentation skills. (c) Contrary to the robust transfer of learning gains to different stimuli within a given task, there was no significant transfer across tasks indicating that the locus of learning was task dependent. Altogether our results suggest that even given explicit letter instruction, training on word decoding may result in letter recognition rather than in alphabetic segmentation skills. (C) 2002 Elsevier Science B.V. All rights reserved.