The effects of meditation on attentional capacity, emotion regulation, and sensory information processing

Abstract

Emerging evidence suggests beneficial effects of meditation generally, and mindfulness meditation specifically, on mental health and well-being via improved cognitive functioning and emotion regulation. The exact mechanisms underlying these effects, however, are yet to be fully understood, which is an overarching aim of three related studies reported in the thesis. One possible mechanism facilitating both more efficient attentional processing and emotion regulation in meditators is reduced attentional capture by salient stimuli, quantified in the present research using Attentional Blink (AB) phenomenon - a temporary inability to consciously perceive an attended stimulus when it is shortly preceded by another. Previous research using AB paradigms with neutral and emotional stimuli (referred to as Neutral Attention Blink (NAB) and Emotional Attentional Blink (EAB) paradigms, respectively) has shown that meditation practice (particularly mindfulness as secularly defined) attenuates NAB. Lower NAB has also been associated with higher trait non-reactivity (an aspect of mindfulness), both dispositional (innate) and trained through meditation practice. Study 1 (online behavioural study) investigated the effects of meditation on AB using both the NAB and EAB paradigms in meditators (n = 75) and non-meditators (n = 54), as well as the relationships of NAB and EAB magnitude with each other and with trait non-reactivity and equanimity (non-attachment), with the latter being another aspect of mindful awareness that should attenuate attentional capture by salient (emotional) stimuli. There were no significant NAB or EAB differences between meditators and non-meditators. However, lower EAB was significantly associated with higher trait non-reactivity and equanimity in meditators as a group and in the meditator practicing mindfulness as secularly defined, suggesting that non-reactivity and equanimity might be attenuating EAB via reduced attentional capture by emotional stimuli. Another mechanism that has been proposed to underlie AB is ‘gating’ or filtering of the sensory stimuli as a way to protect the processing of the first stimulus, given limited attentional capacity resources. Sensory gating is a fundamental mechanism protecting limited attentional processing capacity by an automatic inhibition of subsequent stimuli whilst the current stimulus is being processed and has been extensively studied using Prepulse Inhibition (PPI) – a modulation of the startle reflex when a startling stimulus (pulse) is preceded by a stimulus of less intensity (prepulse). Study 2 (lab-based study) explored the relationships of PPI with AB (with the focus on NAB) as well as with trait non-reactivity and equanimity in a separate sample of meditators (n = 23) and non-meditators (n = 21). There were no significant PPI differences between meditators and non-meditators and no significant associations of PPI with trait non-reactivity or equanimity. However, higher PPI was significantly associated with slower reaction times during NAB paradigm performance. The implications of this finding for the shared (or similar) mechanisms underlying AB and PPI are not clear, but given that PPI is an index of sensorimotor gating, they point to the relationship between automated (PPI) and voluntary (NAB) motor aspects engaged by the two paradigms. Yet another mechanism by which non-reactivity and equanimity might exert their attenuating effect on AB is the reduced activation of associative semantic memory networks in response to conceptually meaningful and/or emotionally salient stimuli, which has been observed in meditators in previous research. Associative semantic memory networks activation, alongside attentional capture, has been proposed as one of the mechanisms underlying the Affective Priming (AP) phenomenon – an impact that a first stimulus (prime) has on the speed and evaluation of the subsequent stimulus (target). Study 3 (online behavioural study) investigated the effects of meditation on AP and its relationship with EAB as well as trait non-reactivity and equanimity in meditators (n = 49) and non-meditators (n = 55) (a subsample of Study 1 participants). Congruent (same valence of primes and targets) and incongruent (opposite valence of primes and targets) were used in the AP paradigm. As expected, meditators were less impacted by the emotional valence of the primes or their congruity/incongruity with the targets, whereas non-meditators (particularly females) showed a strong priming effect. The correlation pattern between AP and EAB was somewhat inconsistent. Lower AP was associated with higher trait non-reactivity and equanimity in meditators for incongruent condition, suggesting that smaller AP in meditators may be due to reduced activation by the primes of associative semantic networks. Together, the findings highlight trait non-reactivity and equanimity as the mechanisms underlying the effects of meditation generally, and mindfulness meditation specifically, on attentional capacity and emotion regulation via reduced attentional capture and semantic associative network activation by affective stimuli. Longitudinal studies using the AB, PPI, and AP paradigms are required to further investigate where the observed cross-sectional and correlational findings are the effects of meditation rather than pre-existing individual differences between meditators and non-meditations (and within meditators) with the view of developing particularly AB and AP paradigms as objective tools of meditation practice on attentional capacity and emotion regulation.