Modulation of event-related potentials of visual discrimination by meditation training and sustained attention

Sustained attention tasks often reduce the ability to discriminate goal-relevant stimuli over time. Intensive training in shamatha (focused-attention) meditation can improve perceptual discrimination of difficult-to-see visual stimuli. In two 3-month meditation retreats, participants performed a continuous performance task at three time points. In Retreat 1, the target difficulty was adjusted to match each participant's improving perceptual capacity, and no training effects on brain activity were observed. In Retreat 2, the target difficulty was held constant, leading to earlier onset of sensory brain signals and reduced performance decline over time. Changes in later processing stages correlated with improvements in perceptual threshold. The findings suggest that meditation-related improvements in perceptual discrimination can alter electrophysiological markers of attention and perception, but only when task demands allow discrimination capacity to exceed target difficulty.

Study at a glance

Abstract

The ability to discriminate among goal-relevant stimuli tends to diminish when detections must be made continuously over time. Previously, we reported that intensive training in shamatha (focused-attention) meditation can improve perceptual discrimination of difficult-to-detect visual stimuli (MacLean et al., 2010). Here we extend these findings to examine how discrimination difficulty and meditation training interact to modulate event-related potentials of attention and perceptual processing during vigilance. Training and wait-list participants completed a continuous performance task (CPT) at the beginning, middle, and end of two 3-month meditation interventions. In the first intervention (Retreat 1), the CPT target was adjusted across assessments to match training-related changes in participants’ perceptual capacity. In the second intervention (Retreat 2), the target was held constant across training, irrespective of changes in discrimination capacity. No training effects were observed in Retreat 1, whereas Retreat 2 was associated with changes in the onset of early sensory signals and an attenuation of within-task decrements at early latencies. In addition, changes at later stimulus processing stages were directly correlated with improvements in perceptual threshold across the second intervention. Overall, these findings demonstrate that improvements in perceptual discrimination can modulate electrophysiological markers of perceptual processing and attentional control during sustained attention, but likely only under conditions where an individuals’ discrimination capacity is allowed to exceed the demand imposed by the difficulty of a visual target. These results contribute to basic understanding of the dependence of perceptual processing and attentional control to contextual demands, and their susceptibility to directed mental training.