Multimodal Temporal Perception in Musicians: Evidence for Both Segregated and Supramodal Attentional Systems?

Multimodal Temporal Perception in Musicians: Evidence for Both Segregated and Supramodal Attentional Systems? Ahnate Lim (ahnate@hawaii.edu) Department of Psychology, University of Hawaii at Manoa 2530 Dole Street, Honolulu, HI 96822 USA Scott Sinnett (ssinnett@hawaii.edu) Department of Psychology, University of Hawaii at Manoa 2530 Dole Street, Honolulu, HI 96822 USA Abstract Although musical training has been correlated with modulations of early perceptual and attentional processes, the majority of investigations neglect the possibility of cross modality enhancements. We investigated the effects of musical training by measuring spatial and temporal attention in a temporal order judgment task in auditory, visual, and crossmodal conditions with and without non-predictive cues. In Experiment 1, musicians had lower detection thresholds when compared to controls in all conditions (marginal in auditory). Experiment 2 showed mixed findings, with musicians demonstrating reduced capture from visual cues on the visual task compared to controls, and lower detection thresholds on the auditory task with visual cues. Adding spatial cues to the temporal order judgment tasks increased temporal thresholds for both groups, but only when they occurred within the same modality as the task, and not when presented in a different modality. The findings support both supramodal and segregated accounts of attentional resources. Keywords: attention; perception; musicians; temporal order judgment; multisensory; visual; auditory; crossmodal Introduction The human attentional system is impressively competent at processing information, considering how the efficiency and selectivity of attention facilitates perception and goal directed behavior amidst a constant plethora of stimuli. Interestingly, the neurological underpinnings of attention may change under certain conditions. This “plasticity” has been associated with compensations for losses in one sensory modality with enhancements in another modality (Roder et al., 1999). Furthermore, improved behavioral performance may also occur as a side effect of specific activities or hobbies such as video game playing (Granek, Gorbet, & Sergio, 2010; Green, Li, & Bavelier, 2010, but see Boot, Blakely, & Simons, 2011) and musical training (Hodges, Hairston, & Burdette, 2005; Lim & Sinnett, 2011). Although the topic of non-musical cognitive benefits (e.g., mathematics, spatial-reasoning and linguistics) occurring as a result of musical training has been the focus of much research (for a summary, see Rauscher, 2003), there has been less emphasis on the effects of precise mechanisms of attention and perception. There is evidence from numerous studies conducted with musicians suggesting greater neuroplasticity when compared with non- musicians (see for example, Gaser & Schlaug, 2003; Munte, Altenmuller, & Jancke, 2002). Although it should be noted that these brain differences could equally be attributed to a predisposition that leads people to become musicians, rather than any specific training related enhancement. Even so, behavioral evidence from studies comparing musicians to non-musicians demonstrates improved perceptual abilities on various tasks in different modalities. These have included visual perceptual speed and discrimination (Helmbold, Rammsayer, & Altenmuller, 2005; Patston, Hogg, & Tippett, 2007) as well as auditory temporal discrimination (Hodges et al., 2005; Jones & Yee, 1997). These studies also highlight an interesting possibility of training effects on attention: crossmodal enhancements (e.g., visual enhancements after auditory training). Some authors have suggested that the attentional system operates in a supramodal fashion, with all senses having access to a single reservoir of attentional resources (see Farah, Wong, Monheit, & Morrow, 1989; Pavani, Husain, Ladavas, & Driver, 2004; but see also Sinnett, Costa, & Soto-Faraco, 2006; C Spence & Driver, 1996; Wickens, 1984, for examples of a segregated attentional system). Thus, by testing musicians for enhanced attentional and perceptual capabilities in the visual modality, we can indirectly assess whether training in one sense (i.e., auditory musical training) leads to performance enhancements in another. This would provide support for a supramodal attentional system, and would closely align with recent investigations involving video game players, where auditory enhancements were observed despite the training being mostly visual based (Donohue, Woldorff, & Mitroff, 2010; Green, Pouget, & Bavelier, 2010). The temporal order judgment (TOJ) task is an ideal tool to assess temporal processing differences between musicians and non-musicians. More importantly, the TOJ task can be presented under both unimodal and crossmodal conditions. The task requires participants to determine the correct order of subsequently presented stimuli, and allows for two measures of perceptual processing to be calculated: the just noticeable difference (JND), and the point of subjective simultaneity (PSS). The JND is a measure of the resolution or threshold of temporal discrimination, while the PSS is the time in which one stimulus can be presented before the other such that they are still perceived as occurring simultaneously (e.g., in a crossmodal task, it can indicate whether auditory or visual stimuli must be presented first for them to be perceived as simultaneous).