In the DFWT, each participant listens to pairs of monosyllabic rhyming consonant-vowel-consonant (CVC) words. (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. It was originally explored by Johnson et al. The 'dichotic fused words test' (DFWT) is a modified version of the basic dichotic listening test. Even though the listeners heard two separate signals with neither ear receiving a 'complete' vowel sound, they could still identify the syllable sounds.ĭichotic listening test designs Dichotic fused words test (DFWT) The formants of vowel sounds and their relation are crucial in differentiating vowel sounds. The name for this demonstration continued to evolve and was finally named 'dichotic perception' or 'dichotic listening.' Around the same time, Jim Cutting (1976), an investigator at Haskins Laboratories, researched how listeners could correctly identify syllables when different components of the syllable were presented to different ears. Ultimately, in comparison to the binaural condition, 'peripheral masking is avoided when speech is heard dichotically.' This demonstration was originally known as 'the Rand effect' but was later renamed 'dichotic release from masking'. F2 and F3 varied in low and high intensity. In his study, the first stimuli: formant (F1), was presented to one ear while the second and third stimuli:(F2) and (F3) formants, were presented to the opposite ear. He interpreted this result as indicating right-hemisphere dominance for pitch discrimination.ĭuring the early 1970s, Tim Rand demonstrated dichotic perception at Haskins Laboratories. In another example, Sidtis (1981) found that healthy adults have a left-ear advantage on a dichotic pitch recognition experiment.

A dichotic listening performance advantage for one ear is interpreted as indicating a processing advantage in the contralateral hemisphere. In the late 1960s and early 1970s, Donald Shankweiler and Michael Studdert-Kennedy of Haskins Laboratories used a dichotic listening technique (presenting different nonsense syllables) 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 and is typically processed in the left cerebral hemisphere. From that study, and others studies using neurological patients with brain lesions, she concluded that there is a predominance of the left hemisphere for speech perception, and a predominance of the right hemisphere for melodic perception. She demonstrated, for example, that healthy participants have a right-ear superiority for the reception of verbal stimuli, and left-ear superiority for the perception of melodies. In the early 1960s, Doreen Kimura used dichotic listening tests to draw conclusions about lateral asymmetry of auditory processing in the brain. He suggested that due to limited capacity, the human information processing system needs to select which channel of stimuli to attend to, deriving his filter model of attention. In the 1950s, Broadbent employed dichotic listening tests in his studies of attention, asking participants to focus attention on either a left- or right-ear sequence of digits. History ĭonald Broadbent is credited with being the first scientist to systematically use dichotic listening tests in his work. In one type of test, participants are asked to pay attention to one or both of the stimuli later, they are asked about the content of either the stimulus they were instructed to attend to or the stimulus they were instructed to ignore. In a standard dichotic listening test, a participant is presented with two different auditory stimuli simultaneously (usually speech), directed into different ears over headphones. It is used within the fields of cognitive psychology and neuroscience. Used to investigate auditory laterality and selective attentionĭichotic listening is a psychological test commonly used to investigate selective attention and the lateralization of brain function within the auditory system. Auditory test to assess selective attention Dichotic listening

Dichotic listening theory