Task-dependent costs in processing two simultaneous auditory stimuli

Abstract

When presented with two speech utterances, one to each ear (i.e., dichotically), listeners can be asked to either (1) ignore one and report the other (selective attention) or (2) report both (divided attention). Despite more than 50 years of research on this topic, it is still not fully understood why different stimulus configurations exert such a great influence on the degree of success listeners experience when asked to either select one utterance or divide their auditory attention between two utterances. The goal of this study was to explore the theoretical distinction between selective and divided attention by presenting a method for distinguishing between the two processes in a single study. The new set of experimental results demonstrates the value of measuring both processes within the same study and provides an example of the sorts of hypotheses that such a technique can be used to generate.Two different types of experimental approaches have generally been used to examine the processing of multiple speech stimuli. The first type is what we will refer to as the dual-ear experiment (although, for comparisons, most such experiments have contained single-ear and/or diotic conditions as well). Dual-ear experiments are distinguished from other experiments involving speech stimuli by the fact that they include the presentation of one speech utterance to one ear and another utterance to the other ear, and in terms of results, they tend to emphasize the fact that under some conditions listeners can reliably report the information presented to the "target" ear with very few errors (e.g., Broadbent, 1958;Cherry, 1953;Moray, 1970;Treisman, 1964Treisman, , 1969Wood & Cowan, 1995).The second type is the informational masking approach, in which researchers have generally presented multiple speech stimuli to the same ear (although various types of dichotic presentation have also been used) and have emphasized the factors that lead to errors in processing only one of two simultaneously presented stimuli (e.g., Brungart, Simpson, Ericson, & Scott, 2001). The term informational masking is often defined in contrast to energetic masking, which refers to a reduction in performance that can be accounted for by the degree to which the masker overlaps the target at a set of peripheral analyzers (usually the cochlea or the auditory nerve). Informational masking, it is argued, is caused by nonperipheral factors, principally masker uncertainty and target-masker similarity (for examples, see Durlach et al., 2003;Neff, 1995;Neff & Green, 1987;Watson & Kelly, 1981; for a review, see Kidd, Mason, Richards, Gallun, & Durlach, 2006). A substantial number of studies have demonstrated that speech stimuli can interfere with each other in ways that are not easily captured by energetic masking alone (e.g., Arbogast, Mason, & Kidd, 2002;Brungart & Simpson, 2002;Brungart, Simpson, Darwin, Arbogast, & Kidd, 2005;Brungart et al., 2001;Freyman, Balakrishnan, & Helfer, 2001Freyman, Helfer, McCall, & Clifton, 1999;Kidd, Arbogast, Mason, & Gallun, 20...

Auditory attention strategy depends on target linguistic properties and spatial configuration

“…Using similar stimuli presented dichotically, Gallun et al (2007) found that dividing attention across two streams entailed a decrease in performance (compared to selective attention trials with the same stimuli) when the task in both ears involved keyword identification. Although the dichotic stimulus presentation prevents drawing any conclusions about the spatial profile of auditory attention from this study, the authors did find an interesting dual-task effect: listening for keywords in both streams (and only afterward being cued which stream to report) yielded a performance cost, compared to a task that required merely detecting the presence or absence of speech in noise in one ear while reporting keywords in speech delivered to the other ear.…”

Perceiving the speech of multiple concurrent talkers in a combined divided and selective attention task

“…In recent years, divided and selective attention have been increasingly studied using the Coordinate Response Measure (CRM) corpus (Bolia et al, 2000;Kidd et al, 2005, Humes et al, 2006, Gallun et al, 2007, Shinn-Cunningham and Ihlefeld, 2004. This corpus combines a large number of naturally spoken utterances with easily measurable performance levels.…”

Effects of dynamic range compression on spatial selective auditory attention in normal-hearing listeners

“…Similar results can occur even in diotic mixtures (increased "reversals"; Stone et al, 2009), indicating that overall cognitive load, and not necessarily spatial factors, may also contribute to our results. In considering this possibility, it is important to note that the previous study that found increased reversals for diotic mixtures used a cognitively demanding task in which subjects divided attention between two simultaneous streams (see also Gallun et al, 2007;Best et al, 2010) and responded only after performing an unrelated, visual distractor task (further increasing cognitive load). In addition, in that study listeners could report the content of the two streams in any order for them to be counted as correct.…”