Temporal Prediction in lieu of Periodic Stimulation

Abstract

Predicting not only what will happen, but also when it will happen is extremely helpful for optimizing perception and action. Temporal predictions driven by periodic stimulation increase perceptual sensitivity and reduce response latencies. At the neurophysiological level, a single mechanism has been proposed to mediate this twofold behavioral improvement: the rhythmic entrainment of slow cortical oscillations to the stimulation rate. However, temporal regularities can occur in aperiodic contexts, suggesting that temporal predictions per se may be dissociable from entrainment to periodic sensory streams. We investigated this possibility in two behavioral experiments, asking human participants to detect near-threshold auditory tones embedded in streams whose temporal and spectral properties were manipulated. While our findings confirm that periodic stimulation reduces response latencies, in agreement with the hypothesis of a stimulus-driven entrainment of neural excitability, they further reveal that this motor facilitation can be dissociated from the enhancement of auditory sensitivity. Perceptual sensitivity improvement is unaffected by the nature of temporal regularities (periodic vs aperiodic), but contingent on the co-occurrence of a fulfilled spectral prediction. Altogether, the dissociation between predictability and periodicity demonstrates that distinct mechanisms flexibly and synergistically operate to facilitate perception and action.

Keywords: auditory perception; behavior; oscillation; prediction; psychophysics; rhythm.

Figure 1.

Experiment 1. A, Each trial consisted of a stream of simultaneous auditory and visual stimuli. Reference stimuli corresponded to a 440 Hz (red) pure tone co-occurring with a white cross. A red circle specified occasional target stimuli, on which participants had to discriminate between a standard (440 Hz, red) and deviant (880 Hz, blue) pure tone. B, We investigated three conditions whereby the presented auditory streams were : 1) periodic predictable (PP; at 1.3, 2.25, 2.9, 3.45, or 3.9 Hz), 2) aperiodic predictable (AP), or 3) aperiodic unpredictable (AU). Notice that similar SOAs were used across the three conditions. C, D, Average sensitivity (C, d′) and correct reaction times (D, Correct R.T., in seconds) for the three conditions. E, Pearson correlation across participants between the effect of temporal predictability (AP vs AU)—or stimulus periodicity (PP vs AP); or both (PP vs AU)—on d′ and on Correct R.T. Error bars indicate SEM. Stars indicate significant differences (n = 19; p < 0.05). n.s., Significant absence of differences (Bayes factor, <0.33).

Figure 2.

Experiment 2. A, Each trial consisted of a stream of simultaneous auditory and visual stimuli. Reference stimuli were composed of a (pink or blue) noise co-occurring with a white cross, while a red circle specified occasional target stimuli. On them, participants had to detect the possible occurrence (50%) of a pure tone embedded in the noise. To modulate temporal predictions, reference stimuli were either presented with a fixed or jittered SOA. To modulate spectral prediction, the (blue or pink) noises presented during reference and target stimuli were either similar or different. Notice that pre-target and post-target SOAs were kept constant across conditions. B, C, Average sensitivity (B, d′) and correct reaction times (C, Correct R.T., in seconds) as a function of temporal and spectral predictions. D, Pearson correlation across participants between the (main) effect of temporal (T⁺ vs T⁻)—or spectral (S⁺ vs S⁻)—predictability on d′ and on Correct R.T. Same conventions as Figure 1 (n = 20).