Explicit lip-reading can be reliably tested in hearing preschoolers by asking them to 'say aloud what I say silently'. In school-age children, lipreading of familiar closed-set words such as number words can be readily elicited. Individual differences in lip-reading skill, as tested by asking the child to 'speak the word that you lip-read', or by matching a lip-read utterance to a picture, show a relationship between lip-reading skill and age. In hearing adults: lifespan considerations While lip-reading silent speech poses a challenge for most hearing people, adding sight of the speaker to heard speech improves speech processing under many conditions. The mechanisms for this, and the precise ways in which lip-reading helps, are topics of current research. Seeing the speaker helps at all levels of speech processing from phonetic feature discrimination to interpretation of pragmatic utterances. The positive effects of adding vision to heard speech are greater in noisy than quiet environments, where by making speech perception easier, seeing the speaker can free up cognitive resources, enabling deeper processing of speech content. As hearing becomes less reliable in old-age, people may tend to rely more on lip-reading, and are encouraged to do so. However, greater reliance on lip-reading may not always make good the effects of age-related hearing loss. Cognitive decline in aging may be preceded by and/or associated with measurable hearing loss. Thus lipreading may not always be able to fully compensate for the combined hearing and cognitive age-related decrements. In specific (hearing) populations A number of studies report anomalies of lipreading in populations with distinctive developmental disorders. Autism: People with autism may show reduced lipreading abilities and reduced reliance on vision in audiovisual speech perception. This may be associated with gaze-to-the-face anomalies in these people. Williams syndrome: People with Williams syndrome show some deficits in speechreading which may be independent of their visuo-spatial difficulties. Specific Language Impairment: Children with SLI are also reported to show reduced lipreading sensitivity, as are people with dyslexia. Deafness Debate has raged for hundreds of years over the role of lip-reading ('oralism') compared with other communication methods (most recently, total communication) in the education of deaf people. The extent to which one or other approach is beneficial depends on a range of factors, including level of hearing loss of the deaf person, age of hearing loss, parental involvement and parental language(s). Then there is a question concerning the aims of the deaf person