Mental training affects distribution of limited brain resources.
The information processing capacity of the human mind is limited, as is evidenced by the so-called "attentional-blink" deficit: When two targets (T1 and T2) embedded in a rapid stream of events are presented in close temporal proximity, the second target is often not seen. This deficit is believed to result from competition between the two targets for limited attentional resources. Here we show, using performance in an attentional-blink task and scalp-recorded brain potentials, that meditation, or mental training, affects the distribution of limited brain resources. Three months of intensive mental training resulted in a smaller attentional blink and reduced brain-resource allocation to the first target, as reflected by a smaller T1-elicited P3b, a brain-potential index of resource allocation. Furthermore, those individuals that showed the largest decrease in brain-resource allocation to T1 generally showed the greatest reduction in attentional-blink size. These observations provide novel support for the view that the ability to accurately identify T2 depends upon the efficient deployment of resources to T1. The results also demonstrate that mental training can result in increased control over the distribution of limited brain resources. Our study supports the idea that plasticity in brain and mental function exists throughout life and illustrates the usefulness of systematic mental training in the study of the human mind. (+info
Enhanced identification of smoking-related words during the attentional blink in smokers.
The attentional blink (AB) occurs when ongoing processing of one target (T1) in a series of rapidly presented stimuli impairs processing of a subsequently presented second target (T2), such that T2 cannot be consciously perceived or reported. There is evidence that the AB can be influenced by the emotional or motivational salience of T2. We examined whether the AB could be attenuated by smoking-related stimuli in smokers. Heavy smokers (N=55) performed an AB task on two occasions, once following 12-h of abstinence and once following ad libitum smoking. T2s were either smoking-related or neutral (household-related) words, and lagged T1 by 0 to 7 distracter words. T1s were all neutral words. Each word was presented for 130 ms. Subjects were required to recall T1 and T2 immediately after each trial. There was a significant word type by lag interaction, whereby smoking-related T2s were recalled better than neutral T2s at early, but not late, lags. The word type effect at early lags was significantly associated with attentional bias assessed on the smoking Stroop task, but was not significantly moderated by abstinence. These data indicate that, in heavy smokers, smoking-related stimuli are more likely to engage conscious awareness than neutral words under conditions of limited attentional resources. (+info
Attentional blinks as errors in temporal binding.
In the attentional blink [Raymond, J. E., Shapiro, K. L., & Arnell, K. M. (1992). Temporary suppression of visual processing in an RSVP task: An attentional blink? Journal of Experimental Psychology: Human Perception and Performance, 18(3), 849-860.], the second of two targets in a Rapid Serial Visual Presentation (RSVP) stream is difficult to detect and identify when it is presented soon but not immediately after the first target. We varied the Stimulus Onset Asynchrony (SOA) of the items in the stream and the color of the targets (red from gray or vice versa), and looked at the responses to the second target. Exact responses to the second target (zero positional error) showed a typical attentional blink profile, with a drop in performance for an interval of 200-500 ms after the first target. Approximate responses (positional error no greater than 3 frames) showed no such drop in performance, although results were still dependent on color (better for red) and increased with increasing SOA. These findings are consistent with a two-stage model of visual working memory, where encoding of the first target disrupts attention to (and temporal binding of) the second target. We suggest that this disruption occurs within a certain time (approximately 0.5 s) after the first target, during which period salient distractors are as likely as the second target to enter working memory. (+info
The blinking spotlight of attention.
Increasing evidence suggests that attention can concurrently select multiple locations; yet it is not clear whether this ability relies on continuous allocation of attention to the different targets (a "parallel" strategy) or whether attention switches rapidly between the targets (a periodic "sampling" strategy). Here, we propose a method to distinguish between these two alternatives. The human psychometric function for detection of a single target as a function of its duration can be used to predict the corresponding function for two or more attended targets. Importantly, the predicted curves differ, depending on whether a parallel or sampling strategy is assumed. For a challenging detection task, we found that human performance was best reflected by a sampling model, indicating that multiple items of interest were processed in series at a rate of approximately seven items per second. Surprisingly, the data suggested that attention operated in this periodic regime, even when it was focused on a single target. That is, attention might rely on an intrinsically periodic process. (+info
Noradrenergic neuromodulation of human attention for emotional and neutral stimuli.
INTRODUCTION: Norepinephrine (NE) has a regulatory role in human attention. OBJECTIVE: To examine its role in emotional modulation of attention, we used an attentional blink (AB) paradigm, in the context of psychopharmacological manipulation, where targets were either emotional or neutral items. RESULTS AND DISCUSSION: We report behavioural evidence that beta-adrenergic blockade with propranolol impairs attention independent of target valence. Furthermore, this effect is centrally mediated as administration of the peripheral beta-adrenergic antagonist nadolol did not impair attention. By contrast, increasing NE tone, using the selective NE reuptake inhibitor reboxetine, improves detection of emotional stimuli. CONCLUSION: In line with theoretical and animal models, these findings provide human behavioural evidence that the adrenergic system has a modulatory influence on selective attention that in some instances depends on item valence. (+info
Temporal selection is suppressed, delayed, and diffused during the attentional blink.
Personal names do not always survive the attentional blink: Behavioral evidence for a flexible locus of selection.
No differential attentional blink in dyslexia after controlling for baseline sensitivity.