The logogen model of speech processing was developed by Morton (1969). The model is based on the assumption that listeners have a vast number of specialized recognition units, that each are able to recognize one specific word. The recognition units are called logogens, and these contain information about the sounds of the word, its syntactic and semantic characteristics, and information about word type. All logogens have a scale indicating the activation level of the logogen. The incoming speech signal is presented to all logogens, and all logogens which match the incoming information are raised in activation. With each following matching sound, the activation increases until a certain critical activation value is reached: the fire threshold. As soon as the activation level of the logogen exceeds the threshold, the logogen fires: at this moment, the word is recognized and all information about the word becomes available. Once a logogen fires, all activation levels of competing logogens immediately decrease to their rest level. Apart from the model's inefficiency (before selection, activation only increases, it cannot not decrease), the important role of context allows for the possibility that a word is recognised that deviates strongly from the acoustic input.
- Morton, J. 1969. 'Interaction of information in word recognition.' Psychological Review 76, 165-178