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Dichotic listening is a psychological test commonly used to investigate selective attention within the auditory system and is a subtopic of cognitive psychology and neuroscience. Specifically, it is "used as a behavioral test for hemispheric lateralization of speech sound perception." During a standard dichotic listening test, a participant is presented with two different auditory stimuli simultaneously (usually speech). The different stimuli are directed into different ears over headphones. Research Participants were instructed to repeat aloud the words they heard in one ear while a different message was presented to the other ear. As a result of focusing to repeat the words, participants noticed little of the message to the other ear, often not even realizing that at some point it changed from English to German. At the same time, participants did notice when the voice in the unattended ear changed from a male’s to a female’s, suggesting that the selectivity of consciousness can work to tune in some information." ==Test designs== Dichotic Fused Words Test (DFWT) The "Dichotic Fused Words Test" (DFWT) is a modified version of the basic dichotic listening test. It was originally explored by Johnson ''et al.'' (1977) but in the early 80's Wexler and Hawles (1983) modified this original test to ascertain more accurate data pertaining to hemispheric specialization of language function. In the DFWT, each participant listens to pairs of monosyllabic rhyming consonant-vowel-consonant (CVC) words. Each word varies in the initial consonant. The significant difference in this test is "the stimuli are constructed and aligned in such a way that partial interaural fusion occurs: subjects generally experience and report only one stimulus per trial." According to Zatorre (1989), some major advantages of this method include "minimizing attentional factors, since the percept is unitary and localized to the midline" and "stimulus dominance effects may be explicitly calculated, and their influence on ear asymmetries assessed and eliminated."〔 Wexler and Hawles study obtained a high test-retest reliability (r=0.85).〔 High test-retest reliability is good, because it proves that the data collected from the study is consistent. Testing with Emotional Factors An emotional version of the dichotic listening task was developed. In this version individuals listen to the same word in each ear but they hear it in either a surprised, happy, sad, angry, or neutral tone. Participants are then asked to press a button indicating what tone they heard. Usually dichotic listening tests show a right-ear advantage for speech sounds. Right-ear/left-hemisphere advantage is expected, because of evidence from Broca's area and Wernicke's area, which are both located in the left hemisphere in most of right-handed people. In contrast, the left ear (and therefore the right hemisphere) is often better at processing nonlinguistic material. The data from the emotional dichotic listening task is consistent with the other studies, because participants tend to have more correct responses to their left ear than to the right. It is important to note that the emotional dichotic listening task is seemingly harder for the participants than the phonemic dichotic listening task. Meaning more incorrect responses were submitted by individuals. Manipulation of Voice Onset Time (VOT) The manipulation of voice onset time (VOT) during dichotic listening tests have given many insights regarding brain function.〔 To date, the most common design is the utilisation of four VOT conditions: short-long pairs (SL), where a Consonant-Vowel (CV) syllable with a short VOT is presented to the left ear and a CV syllable with a long VOT is presented to the right ear, as well as long-short (LS), short-short (SS) and long-long (LL) pairs. In 2006, Rimol et al. first reported that in healthy adults SL pairs elicit the largest right ear advantage (REA) while, in fact, LS pairs elicit a significant left ear advantage (LEA). A study of children 5–8 years old has shown a developmental trajectory whereby long VOTs gradually start to dominate over short VOTs when LS pairs are being presented under dichotic conditions. Converging evidence from studies of attentional modulation of the VOT effect shows that around age 9 children lack the adult-like cognitive flexibility required to exert top-down control over stimulus-driven bottom-up processes. Arciuli et al.(2010) further demonstrated that this kind of cognitive flexibility is a predictor of proficiency with complex tasks such as reading. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Dichotic listening test」の詳細全文を読む スポンサード リンク
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