It is well known that adding a constant time lag between produced actions and resulting auditory feedback disrupts the timing of production (called delayed auditory feedback, DAF, Black, 1951; Lee, 1950). Types of disruption include slowing of production rate and increased variability of timing. Some explanations of this phenomenon have emphasized phase relationships between actions and feedback (e.g., Finney & Warren, 2003; Howell et al., 1983; Pfordresher & Palmer, 2002), whereas others have emphasized the absolute temporal separation between actions and sounds (e.g., MacKay, 1987). One limitation caused by using only delays with constant time lags is that performers can adapt perception/action phase relationships during delayed feedback conditions, but cannot alter the absolute temporal separation between actions and feedback. This differential flexibility may enhance performers’ sensitivity to phase relationships.
The current research examined performance with delayed feedback in which delay lengths were either fixed (i.e., based on absolute time, like typical DAF) or adjustable (i.e., phase length based on a proportion of a predicted inter-onset interval, IOI). Performers with varying levels of musical skill produced simple isochronous melodies on a keyboard, or tapped isochronous rhythms, at three different tempi. Trials incorporated a synchronization/continuation paradigm in which experimental feedback conditions (normal or delayed) occurred during the continuation phase. Half the participants heard adjustable delays and the other half heard fixed delays during delayed feedback trials. Disruption of timing from delays was measured using production rate (mean IOI) and timing variability (CV = SD / mean IOI), relative to performance with normal feedback.
Results indicated that phase relationships between produced IOIs and delay onsets influence performance timing more so than the absolute separation between produced and feedback onsets. Delayed feedback resulted in slowing of timing and increased timing variability except when delay length was equal to IOIs (resulting in onset synchrony). At the same time, a modest contribution of absolute separation between produced and feedback onsets was evident, with disruption of timing increasing as delays approached 200ms, and decreasing thereafter. Overall, results support a view of temporal coordination between perception and action that incorporates both relative and absolute timing.