Cognitive entrainment to isochronous rhythms is independent of both sensory modality and top-down attention

The anisochrony of a stimulus sequence was manipulated parametrically to investigate whether rhythmic entrainment is stronger in the auditory modality than in the visual modality (Experiment 1), and whether it relies on top-down attention (Experiment 2). In Experiment 1, participants had to respond as quickly as possible to a target presented after a sequence of either visual or auditory stimuli. The anisochrony of this sequence was manipulated parametrically, rather than in an all or none fashion; that is, it could range from smaller to larger deviations of the isochrony (0, 10, 20, 50, 100, 150 and 200 ms). We compared rhythmic entrainment patterns for auditory and visual modalities. Results showed a peak of entrainment for both isochrony and deviations of isochrony up to 50 ms (i. e. , participants were equally fast both after the isochronous sequences and after 10, 20 and 50 ms deviations), suggesting that anisochronous sequences can also produce entrainment. Beyond this entrainment window, the reaction times became progressively slower. Surprisingly, no differences were found between the entrainment patterns for auditory and visual rhythms. In Experiment 2, we used a dual-task methodology by adding a working memory n-back task to the procedure of Experiment 1. Results did not show interference of the secondary task in either auditory or visual modalities, with participants showing the same entrainment pattern as in Experiment 1. These results suggest that rhythmic entrainment constitutes a cognitive process that occurs by default (automatically), regardless of the modality in which the stimuli are presented, and independent of top-down attention, to generate behavioural benefits

La anisocronía de una secuencia de estímulos se ha manipulado paramétricamente para investigar si la sincronización rítmica es más potente en la modalidad auditiva que en la visual (Experimento 1), y si esta depende de procesos de la atención de tipo arriba-abajo (Experimento 2). En el Experimento 1, los participantes tenían que responder lo más rápido posible ante un estímulo objetivo presentado después de una secuencia de estímulos que podían ser visuales o auditivos. La anisocronía de esta secuencia era manipulada paramétricamente en lugar de siguiendo un procedimiento discreto del tipo "todo o nada"; es decir, la anisocronía podía variar en un rango de pequeñas a mayores desviaciones (0, 10, 20, 50, 100, 150 y 200 ms). Los patrones resultantes de la sincronización rítmica fueron comparados para las modalidades auditiva y visual. Los resultados mostraron un pico de sincronización para las condiciones de isocronía y las condiciones de anisocronía que tenían hasta un máximo de 50 ms de desviación (es decir, los participantes respondían igual de rápido para las condiciones de desviación 0, 10, 20 y 50 ms), lo cual sugiere que las secuencias anisócronas también pueden producir sincronización rítmica. A partir de esta ventana de sincronización, los tiempos de reacción fueron progresivamente más altos. Sorprendentemente, no encontramos diferencias en los patrones de sincronización entre los ritmos auditivos y los visuales. En el Experimento 2, utilizamos una metodología de tarea dual mediante la inclusión de una tarea n-back de memoria de trabajo al procedimiento del Experimento 1. Los resultados no mostraron una interferencia de la tarea secundaria ni en la modalidad auditiva ni en la visual, pues los participantes mostraron el mismo patrón de sincronización que en el Experimento 1. Estos resultados sugieren que la sincronización rítmica constituye un proceso cognitivo que beneficia el comportamiento, que ocurre por defecto (automáticamente), independientemente de la modalidad por la que se presenten los estímulos, y que es independiente de procesos "arriba-abajo" de la atención

"Lost in time" but still moving to the beat.

Motor synchronization to the beat of an auditory sequence (e.g., a metronome or music) is widespread in humans. However, some individuals show poor synchronization and impoverished beat perception. This condition, termed "beat deafness", has been linked to a perceptual deficit in beat tracking. Here we present single-case evidence (L.A. and L.C.) that poor beat tracking does not have to entail poor synchronization. In a first Experiment, L.A., L.C., and a third case (L.V.) were submitted to the Battery for The Assessment of Auditory Sensorimotor and Timing Abilities (BAASTA), which includes both perceptual and sensorimotor tasks. Compared to a control group, L.A. and L.C. performed poorly on rhythm perception tasks, such as detecting time shifts in a regular sequence, or estimating whether a metronome is aligned to the beat of the music or not. Yet, they could tap to the beat of the same stimuli. L.V. showed impairments in both beat perception and tapping. In a second Experiment, we tested whether L.A., L.C., and L.V.'s perceptual deficits extend to an implicit timing task, in which they had to respond as fast as possible to a different target pitch after a sequence of standard tones. The three beat-deaf participants benefited similarly to controls from a regular temporal pattern in detecting the pitch target. The fact that synchronization to a beat can occur in the presence of poor perception shows that perception and action can dissociate in explicit timing tasks. Beat tracking afforded by implicit timing mechanisms is likely to support spared synchronization to the beat in some beat-deaf participants. This finding suggests that separate pathways may subserve beat perception depending on the explicit/implicit nature of a task in a sample of beat-deaf participants.

Auditory temporal preparation induced by rhythmic cues during concurrent auditory working memory tasks.

The present study investigated whether participants can develop temporal preparation driven by auditory isochronous rhythms when concurrently performing an auditory working memory (WM) task. In Experiment 1, participants had to respond to an auditory target presented after a regular or an irregular sequence of auditory stimuli while concurrently performing a Sternberg-type WM task. Results showed that participants responded faster after regular compared with irregular rhythms and that this effect was not affected by WM load; however, the lack of a significant main effect of WM load made it difficult to draw any conclusion regarding the influence of the dual-task manipulation in Experiment 1. In order to enhance dual-task interference, Experiment 2 combined the auditory rhythm procedure with an auditory N-Back task, which required WM updating (monitoring and coding of the information) and was presumably more demanding than the mere rehearsal of the WM task used in Experiment 1. Results now clearly showed dual-task interference effects (slower reaction times [RTs] in the high- vs. the low-load condition). However, such interference did not affect temporal preparation induced by rhythms, with faster RTs after regular than after irregular sequences in the high-load and low-load conditions. These results revealed that secondary tasks demanding memory updating, relative to tasks just demanding rehearsal, produced larger interference effects on overall RTs in the auditory rhythm task. Nevertheless, rhythm regularity exerted a strong temporal preparation effect that survived the interference of the WM task even when both tasks competed for processing resources within the auditory modality.