Practice effects in telegraphic speech recognition (Morse Code). Subject performance increases with practice, then levels off for some time, with little apparent improvement with continued practice. During this time, letter recognition is becoming automatic. Automatic letter recognition frees up attentional resources for becoming sensitive to word structure, accounting for a second negatively accelerated learning curve (top line). Recognizing individual words without context (middle line) or individual letters that do not constitute words (bottom line), is always more difficult, and shows no indication of multiple learning stages.