Event-related brain potentials reveal similar attentional mechanisms during selective listening and shadowing.

Abstract

The properties of linguistic attention were examined by recording event-related brain potentials (ERPs) to probe stimuli mixed with dichotically presented prose passages. Subjects either shadowed (repeated phrase by phrase) or selectively listened to one passage while ERPs were recorded from electrodes overlying midline sites, left-hemisphere speech areas, and corresponding areas of the right hemisphere. Mixed with each voice (a male voice in one ear, a female voice in the other) were four probe stimuli: digitized speech sounds (but or /a/ as in father) produced by the same speaker and tone bursts at the mean fundamental and second formant frequencies of that voice. The ERPs elicited by the speech probes in the attended ear showed an enhanced negativity, with an onset at 50 ms-100 ms and lasting up to 800 ms-1,000 ms, whereas the ERPs to the second formant probes showed an enhanced positivity in the 200 ms-300 ms latency range. These effects were comparable for shadowing and selective listening conditions and remained stable over the course of the experiment. The attention-related negativity to the consonant-vowel-consonant probe (but) was most prominent over the left hemisphere; other probes produced no significant asymmetries. The results indicate that stimulus selection during linguistic attention is specifically tuned to speech sounds rather than simply to constituent pure-tone frequencies or ear of entry. Furthermore, it appears that both attentional set and stimulus characteristics can influence the hemispheric utilization of stimuli.

The phonological loop model of working memory: An ERP study of irrelevant speech and phonological similarity effects

“…These increased processing demands may concern the extraction of differentiating stimulus features of the memorized items, which are few and difficult to find in phonological similarity conditions. This is in agreement with several reports that stimuli with less discriminable attributes elicit larger Nds (Alho, Sams, Paavilainen, & Naatanen, 1986;Hansen et a!., 1983;Schwent, Hillyard, & Galambos, 1976;Woods et al, 1984). Thus, according to our results, the phonological similarity effect in memory might be, at least partially, secondary to problems of phonological analysis.…”

“…Perrin, Pernier, & Peronnet, 1988;Naatanen, 1990Naatanen, , 1992Woods, 1990;Woods, Alho, & Algazi, 1991). In tasks that required a phonological analysis, the Nd showed latencies similar to those of our phonological similarity effect (Hansen, Dickstein, Berka, & Hillyard, 1983;Hansen & Hillyard, 1980;Woods, Hillyard, & Hansen, 1984).1…”

Selectively attending to auditory objects

“…The attention-related changes in ERPs occur when participants attend to a particular stream of sounds in the presence of one or more different streams of distracting stimuli and when stimulus sequences are easily discriminated, whether they are distinguished by spatial position, frequency, or both spatial position and frequency (58)(59)(60). Although there is one report of the habituation of the Nde (61), performance and Nde amplitude are usually maintained over long sessions (59,62,63). The Nde amplitudes and latencies are also little affected by repeated testing (34, 64).…”

An Event-related Potential Study of Selective Auditory Attention in Children and Adults

“…A small number of studies have attempted to employ a somewhat more ecologically valid design and have investigated selective spatial attention effects in the context of a spoken narrative; in most cases, the typical ERP attention effects have been observed (Trejo, RyanJones, & Kramer, 1995;Teder, Kujala, & Näätänen, 1993;Woods, Hillyard, & Hansen, 1984;Hink & Hillyard, 1976). For example, irrelevant vowel probes within an attended speech passage elicit more negative ERPs than the same probes in the unattended passage in dichotic presentations (Hink & Hillyard, 1976).…”

“…For example, irrelevant vowel probes within an attended speech passage elicit more negative ERPs than the same probes in the unattended passage in dichotic presentations (Hink & Hillyard, 1976). In a more complex design, Woods et al (1984) presented various speech and tone probe stimuli embedded in dichotically presented prose passages. Speech probes spatially and temporally coincident with the attended passage as compared with the same probes in the unattended passage elicited an enhanced negativity (presumably the Nd) beginning at about 50 msec and lasting to 1000 msec.…”