Timing is everything: Changes in presentation rate have opposite effects on auditory and visual implicit statistical learning

Abstract

Implicit statistical learning (ISL) is exclusive to neither a particular sensory modality nor a single domain of processing. Even so, differences in perceptual processing may substantially affect learning across modalities. In three experiments, statistically equivalent auditory and visual familiarizations were presented under different timing conditions that either facilitated or disrupted temporal processing (fast or slow presentation rates). We find an interaction of rate and modality of presentation: At fast rates, auditory ISL was superior to visual. However, at slow presentation rates, the opposite pattern of results was found: Visual ISL was superior to auditory. Thus, we find that changes to presentation rate differentially affect ISL across sensory modalities. Additional experiments confirmed that this modality-specific effect was not due to cross-modal interference or attentional manipulations. These findings suggest that ISL is rooted in modality-specific, perceptually based processes.

Keywords:

• Implicit learning
• Statistical learning
• Temporal processing
• Multisensory processing
• Perceptual grouping

Notes

¹ The range of visual processing explored in the current paper is restricted: We are examining visual processing and learning of sequentially presented, unfamiliar abstract shapes. Other visual tasks have revealed the visual system to have sophisticated temporal processing (e.g., rapid serial visual presentation of scenes and photographs in Potter, 1976). However, with the current visual task, it is well established that visual processing is relatively poor especially when compared to auditory processing.

² Before familiarization, participants were instructed to attend to a single modality (auditory or visual) depending on their assigned group. They were instructed that stimuli in the other modality were meant to provide distraction. Participants were told to respond to the repeated elements in their assigned modality only. If participants were in the auditory attention group, they were specifically instructed to still look at the monitor but to just direct their attention to the auditory stimuli. Due to a data collection error, repeat responses were not collected. However, the replication of these results in Experiment 3 without unattended stimuli indicates (a) that participants are in fact attending to the assigned sensory modality and (b) that attention to a particular modality was analogous to attention during exposure without unattended stimuli (i.e., there was no interference).

³ In the current experimental methods, there were between 1 and 6 stimuli from a single familiarization stream presented consecutively. The mean number of consecutive stimuli was 3, which, at the rate of presentation employed in Experiment 2, has a duration of 2.25 s. Thus, the average length of pause in an attended familiarization stream, caused by presentation of the unattended familiarization stream, was 2.25 s.