Psycholinguistics is how we use our knowledge of language, speechproduction and comprehension and how a child acquires that knowledge.
How weacquire and process knowledge depends to a great extent on the nature of thatknowledge. Psycholcinguistics have found that speech perception andcomprehension involves deductive processing as well as inductive processing.
Deductive processing as it relates to linguistics is the use of grammatical and contextualinformation where it originates in the brain and influences selection,organzation or interpretion of sensory data. For example, when subjects hearrecorded sentences in which some part of the signal is removed and a cough issubstituted, they "hear" the sentence without a missing phoneme andin fact are unable to say which phonemic segment the cough replaced.
Inductive processing as used by linguists is the use of sensory information of thesignal. In speech understanding, we use stored semantic, lexicial and syntacticinformation as well as the sensory information in the signal itself. Subjectsmake fewer errors identifying words when the words occur in sentences than whenthey are presented in isolation. They do better if the words occur ingrammatical, meaningful sentences as opposed to grammatical, unmeaningfulsentences (Fromkin and Rodman, 1991).