Auditory priming of frequency and temporal information: Effects of lateralised presentation

Abstract

Asymmetric distribution of function between the cerebral hemispheres has been widely investigated in the auditory modality. The current approach borrows heavily from visual local–global research in an attempt to determine whether, as in vision, local–global auditory processing is lateralised. In vision, lateralised local–global processing likely relies on spatial frequency information. Drawing analogies between visual spatial frequency and auditory dimensions, two sets of auditory stimuli were developed. In the high–low stimulus set we manipulate frequency information, and in the fast–slow stimulus set we manipulate temporal information. The fast–slow stimuli additionally mimic visual hierarchical stimulus structure, in which the arrangement of local patterns determines the global pattern. Unlike previous auditory stimuli, the current stimulus sets contain the experimental flexibility of visual local–global hierarchical stimuli allowing independent manipulation of structural levels. Previous findings of frequency and temporal range priming were replicated. Additionally, by presenting stimuli monaurally, we found that priming of frequency ranges (but not temporal ranges) was found to vary by ear, supporting the contention that the hemispheres asymmetrically retain traces of prior frequency processing. These results contribute to the extensive literature revealing cerebral asymmetries for the processing of frequency information, and extend those results to the realm of priming.

Acknowledgements

Alexandra List received support from NIH Training Grant in Human Cognitive Neurosciences T32 MH62997. We would like to thank Lia Ernst for her assistance in running experimental sessions. We are also grateful to Lynn C. Robertson and Barbara Tillmann for helpful discussions.

Notes

¹Monaural presentation of stimuli is intended to provide information asymmetrically to the two cerebral hemispheres. More information or earlier access to information is assumed to reach the contralateral hemisphere compared to the ipsilateral hemisphere. The logic of monaural presentation, therefore, is that by comparing stimuli presented to the left or right ear, differences in performance can indicate hemispheric biases. Crossed anatomical pathways, like those in the visual system, are one possibility in how this might occur. However, even with completely symmetric anatomical connections from each ear to both hemispheres, functional differences could emerge in the cortical responses to input from the different ears. Evidence indicates that there are at least functional contralateral biases in auditory processing. A number of different approaches have supported asymmetric functional representation of contralaterally vs ipsilaterally presented auditory information. In 1951, Rosenzweig recorded ERPs in anaesthetised cats presented with monaural stimulation (clicks). He found increased responses in both hemispheres to contralateral input (compared to ipsilateral input), although the RH showed greater ear differentiation. In humans, various neuroimaging reports have corroborated the functional processing bias for contralateral over ipsilateral stimulation. As measured by MEG, both hemispheres show a differentiation of contralateral and ipsilateral response (e.g., Hertrich, Mathiak, Lutzenberger, & Ackermann, 2004; Mathiak, Hertrich, Lutzenberger, & Ackermann, 2002). Converging results have been reported with fMRI (e.g., Behne, Scheich & Brechmann, 2005; Jancke, Wustenberg, Schulze, & Heinze, 2002; only in nonprimary auditory cortices, Devlin et al., 2003). Monaural stimulation is assumed to tap into these biases, and therefore differences in ear advantage (i.e., performance differences between ear of stimulation) are thought to reveal auditory processing differences between the left and right hemispheres.

²A major difference between the auditory and visual modalities is the property of space. We are convinced by Kubovy and Van Valkenburg's (2001) argument that a visual space:time :: auditory frequency:time analogy is most apt when considering object properties within each modality, as we are.

³When recruiting participants for this and other experiments using these stimuli, we have found that individuals with 5 or more years of musical experience master the discrimination task quickly enough that testing can be completed in 1 hour. Occasionally, although not in this experiment, someone without musical experience has participated and mastered the task within our practice criterion. However, we have not systematically explored the effects of musical expertise on the processing of these stimuli and relegate that question to future research.

⁴A single five-way ANOVA was not run because there were inadequate trials in each cell for the analysis.