In cognitive psychology, dichotic listening is a procedure commonly used to investigate selective attention in the auditory system. Cognitive psychology is a branch of Psychology that investigates internal mental processes such as problem solving memory and language Attention is the Cognitive process of selectively concentrating on one aspect of the environment while ignoring other things The auditory system is the Sensory system for the sense of hearing. In dichotic listening, two different auditory stimuli (usually speech) are presented to the participant simultaneously, one to each ear, normally using a set of headphones. Speech refers to the processes associated with the production and perception of Sounds used in Spoken language. The ear is the sense organ that detects Sounds The Vertebrate ear shows a common biology from Fish to Humans with variations Headphones (also known as earphones, earbuds, stereophones, headsets) are a pair of small Loudspeakers or less commonly a single Participants are asked to attend to one or (in a divided-attention experiment) both of the messages. They may later be asked about the content of either message.
In a selective attention experiment, the participant may be asked to repeat aloud the content of the attended message, a task known as shadowing. As Cherry (1953)[1] found, people recall even the shadowed message poorly, suggesting that most of the processing necessary to shadow the attended message occurs in working memory and is not preserved in the long-term store. Working memory (also referred to as Short term memory, depending on the specific theory is a theoretical construct within Cognitive psychology that refers to the Long-term memory ( LTM) is Memory that can last as little as a few days or as long as decades Performance on the unattended message is, of course, much worse. Participants are generally able to report almost nothing about the content of the unattended message. In fact, a change from English to German in the unattended channel usually goes unnoticed. English is a West Germanic language originating in England and is the First language for most people in the United Kingdom, the United States The German language (de ''Deutsch'') is a West Germanic language and one of the world's major languages. However, participants are able to report that the unattended message is speech rather than non-verbal content.
Tim Rand[1] demonstrated dichotic perception in the late 1960s and early 1970s at Haskins Laboratories[2]. Haskins Laboratories is an independent international multidisciplinary community of researchers conducting basic Research on spoken and written This demonstration was originally known as "the Rand effect" but was subsequently renamed as "dichotic release from masking" and then "dichotic perception" or "dichotic listening. " Another example of a dichotic listening experiment is Jim Cutting's (1976) demonstration[3] at Haskins Laboratories that listeners could correctly identify syllables when different components of the syllable were presented to different ears. Haskins Laboratories is an independent international multidisciplinary community of researchers conducting basic Research on spoken and written The formants of vowel sounds and their relation are crucial in differentiating vowel sounds. A formant is a peak in the Frequency spectrum of a sound caused by acoustic Resonance. Yet even though listeners heard two separate signals (no ear received a 'complete' vowel sound), they could identify the syllable sounds.
Dichotic listening can also be used to test the hemispheric asymmetry of a cognitive function such as language processing. A Longitudinal fissure separates the Human brain into two distinct Cerebral hemispheres connected by the Corpus callosum. Language processing refers to the way human beings process speech or writing and understand it as language In the early 60s Doreen Kimura reported that verbal stimuli presented dichotically gave a right ear advantage (REA)[4]. This was interpreted as showing the result of the structure of the auditory nerves and the left sided dominance for language processing [5]. In the late 1960s and early 1970s Donald Shankweiler [2] and Michael Studdert-Kennedy [3] of Haskins Laboratories used a dichotic listening technique (presenting different nonsense syllables simultaneously to opposite ears) to demonstrate the dissociation of phonetic (speech) and auditory (nonspeech) perception by finding that phonetic structure devoid of meaning is an integral part of language, typically processed in the left cerebral hemisphere[6][7][8]. Michael Studdert-Kennedy is an eminent psychologist and speech scientist Haskins Laboratories is an independent international multidisciplinary community of researchers conducting basic Research on spoken and written Phonetics (from the Greek φωνή ( phonê) "sound" or "voice" is the study of the physical sounds of human speech A cerebral hemisphere ( hemispherium cerebrale) is defined as one of the two regions of the Brain that are delineated by the body's median plane. A dichotic listening performance advantage for one ear is interpreted as indicating a processing advantage in the contralateral hemisphere. A cerebral hemisphere ( hemispherium cerebrale) is defined as one of the two regions of the Brain that are delineated by the body's median plane. In another example, Sidtis (1981)[9] found that healthy adults have a left-ear advantage on a dichotic pitch recognition experiment. He interpreted this result as indicating right-hemisphere dominance for pitch discrimination. For further details about dichotic listening in neuropsychology, see K. Neuropsychology is the applied scientific discipline that studies the structure and function of the Brain related to specific psychological processes and overt behaviors Hugdahl (Ed. ): Handbook of Dichotic Listening. Chichester, UK: John Wiley & Sons, 1988.
References
- ^ Cherry, E. C. (1953). Some experiments on the recognition of speech, with one and two ears. Journal of the Acoustical Society of America 25, pp. 975–979.
- ^ Rand, T. C. (1974). Dichotic release from masking for speech. Journal of the Acoustical Society of America, 55, 678-680.
- ^ Cutting, J. E. (1976). Auditory and linguistic processes in speech perception: inferences from six fusions in dichotic listening. Psychological Review 83, pp. 114–140.
- ^ Kimura, D (1961). Cerebral dominance and the perception of verbal stimuli. Canadian Journal of Psychology, 15, 166-171
- ^ Kimura, D. (1967). Functional asymmetry of the brain in dichotic listening. Cortex, 3, 163-178
- ^ Studdert-Kennedy, M. , & Shankweiler, D. P. (1970). Hemispheric specialization for speech perception. Journal of the Acoustical Society of America, 48, 579-594.
- ^ Studdert-Kennedy, M. , Shankweiler, D. , & Schulman, S. (1970). Opposed effects of a delayed channel on perception of dichotically and monotically presented CV syllables. Journal of the Acoustical Society of America, 48, 599-602.
- ^ Studdert-Kennedy, M. , Shankweiler, D. , & Pisoni, D. (1972). Auditory and phonetic processes in speech perception: Evidence from a dichotic study. Journal of Cognitive Psychology, 2, 455-466.
- ^ Sidtis, J. J. (1981). The complex tone test: Implications for the assessment of auditory laterality effects. Neuropsychologia 19, pp. 103–112.
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