When speaking of captioning, most teachers are familiar with the technology as applied to Closed Captioned Television (CCT). CCT is the captioning service that is typically provided on most television and video programs. This service can be optionally accessed by the viewer and is primarily intended for the hearing impaired. Captions are written, timed and placed using specially designed software. The technology and presentation varies widely in quality and in synchronization. The text may markedly trail the audio model, or there may be omissions and simplifications of text as compared to audio model. (Williams & Thorne, 2000)

       Closed captioning technology was originally designed for the deaf; however there are many studies on the impact of CCT on reading and literacy for hearing audiences (Bean, R.M., & Wilson, R.M., 1989). As a reading source CCT and has been used with some success with second-language readers and as a motivation tool for struggling readers (Goldman &Goldman, 1988). A study by d'Ydewalle (1991) indicated that all readers (including illiterate, emergent, and struggling readers) will both, consciously and unconsciously, track available text. In other words, the student’s eyes will register the text, even if the student is not intentionally trying to read the captioning. A study by the Research Centre for English and Applied Linguistics, University of Cambridge concluded that simultaneous text and audio model presentation can aid novel word acquisition several subsequent studies suggested that captioned television is a motivating medium for below-average readers and bilingual students (Williams & Thorne, 2000; Bird & Williams, 2002). Koskinen et al (1993) strongly demonstrated that simultaneous processing (audio/video/text) enhances learning.

      These studies on the use of CCT as a reading supplementary source showed better results with highly motivated groups, such as second-language acquisition, and moderate results with struggling readers.  Many of these same studies were unable to indicate that CCT benefited language acquisition for SPED populations. However, most CCT studies were able to demonstrate that the addition of CCT as a reading source does no harm to language acquisition. (Koskinen et al, 1993) 

       Probably the most widely used and studied educational application of CCTV is with students learning English as a second language (Closed captioning helps ESOL students, 1991). For those learning English as a second language, captions can reinforce vocabulary and help them learn expressions and speech patterns in spoken English, which are not always reflected in written English (Borras& Lafayette, 1994). Further, “the use of closed captioned primetime television programs with high school ESL students and students in remedial reading programs increased the students' motivation, and resulted in an improvement in their English vocabulary, reading comprehension, and word analysis skills” (Goldman &Goldman, 1988)

      There are some obvious difficulties with CCT studies. Many of the CCT studies made use of poor or low interest media models. For example, a study by Berkay & Boyce (1995) looked at adding captioning to medical profession training videos for intern training in a community college program. This study failed to show any benefit from use of the technology in conjunction with training videos. However, the instructors in this study cited “low student engagement” and “technical inconveniences of equipment and media” as contributing factors to study failure.