individual differences

Speech and Non-Speech Measures of Audiovisual Integration are not Correlated

Many natural events generate both visual and auditory signals, and humans are remarkably adept at integrating information from those sources. However, individuals appear to differ markedly in their ability or propensity to combine what they hear with what they see. Individual differences in audiovisual integration have been established using a range of materials, including speech stimuli (seeing and hearing a talker) and simpler audiovisual stimuli (seeing flashes of light combined with tones). Although there are multiple tasks in the literature that are referred to as “measures of audiovisual integration,” the tasks themselves differ widely with respect to both the type of stimuli used (speech versus non-speech) and the nature of the tasks themselves (e.g., some tasks use conflicting auditory and visual stimuli whereas others use congruent stimuli). It is not clear whether these varied tasks are actually measuring the same underlying construct: audiovisual integration. This study tested the relationships among four commonly-used measures of audiovisual integration, two of which use speech stimuli (susceptibility to the McGurk effect and a measure of audiovisual benefit), and two of which use non-speech stimuli (the sound-induced flash illusion and audiovisual integration capacity). We replicated previous work showing large individual differences in each measure but found no significant correlations among any of the measures. These results suggest that tasks that are commonly referred to as measures of audiovisual integration may be tapping into different parts of the same process or different constructs entirely.

Noise Increases Listening Effort in Normal-Hearing Young Adults, Regardless of Working Memory Capacity

As listening conditions worsen (e.g. background noise increases), additional cognitive effort is required to process speech. The existing literature is mixed on whether and how cognitive traits like working memory capacity moderate the amount of effort that listeners must expend to successfully understand speech. Here, we validate a dual-task measure of listening effort (Experiment 1) and demonstrate that for normal-hearing young adults, effort increases as steady-state masking noise increases, but working memory capacity is unrelated to the amount of effort expended (Experiment 2). We propose that previous research may have overestimated the relationship between listening effort and working memory capacity by measuring listening effort using recall-based tasks. The present results suggest caution in making the general assumption that working memory capacity is related to the amount of effort expended during a listening task.

What Accounts for Individual Differences in Susceptibility to the McGurk Effect?

The McGurk effect is a classic audiovisual speech illusion in which discrepant auditory and visual syllables can lead to a fused percept (e.g., an auditory /bɑ/ paired with a visual /gɑ/ often leads to the perception of /dɑ/). The McGurk effect is robust and easily replicated in pooled group data, but there is tremendous variability in the extent to which individual participants are susceptible to it. In some studies, the rate at which individuals report fusion responses ranges from 0% to 100%. Despite its widespread use in the audiovisual speech perception literature, the roots of the wide variability in McGurk susceptibility are largely unknown. This study evaluated whether several perceptual and cognitive traits are related to McGurk susceptibility through correlational analyses and mixed effects modeling. We found that an individual’s susceptibility to the McGurk effect was related to their ability to extract place of articulation information from the visual signal (i.e., a more fine-grained anal- ysis of lipreading ability), but not to scores on tasks measuring attentional control, processing speed, working memory capacity, or auditory perceptual gradiency. These results provide support for the claim that a small amount of the variability in susceptibility to the McGurk effect is attributable to lipreading skill. In contrast, cognitive and perceptual abilities that are commonly used predictors in individual differences studies do not appear to underlie susceptibility to the McGurk effect.

Measuring Listening Effort: Convergent Validity, Sensitivity, and Links With Cognitive and Personality Measures

Purpose: Listening effort (LE) describes the attentional or cognitive requirements for successful listening. Despite substantial theoretical and clinical interest in LE, inconsistent operationalization makes it difficult to make generalizations across studies. The aims of this large-scale validation study were to evaluate the convergent validity and sensitivity of commonly used measures of LE and assess how scores on those tasks relate to cognitive and personality variables. Method: Young adults with normal hearing (N = 111) completed 7 tasks designed to measure LE, 5 tests of cognitive ability, and 2 personality measures. Results: Scores on some behavioral LE tasks were moderately intercorrelated but were generally not correlated with subjective and physiological measures of LE, suggesting that these tasks may not be tapping into the same underlying construct. LE measures differed in their sensitivity to changes in signal-to-noise ratio and the extent to which they correlated with cognitive and personality variables. Conclusions: Given that LE measures do not show consistent, strong intercorrelations and differ in their relationships with cognitive and personality predictors, these findings suggest caution in generalizing across studies that use different measures of LE. The results also indicate that people with greater cognitive ability appear to use their resources more efficiently, thereby diminishing the detrimental effects associated with increased background noise during language processing.