Twenty-four naïve participants in the dual-task experiment had a mean age of 19.5 years (21 females and three males), with normal or corrected-to-normal colour vision. The comparison of different presentation rates enabled us to test our main hypothesis that the AB will be most prominent at alpha and beta frequencies. Arnell, Howe, Joanisse, & Klein, 2006), where two red letters are embedded in streams of black letters are to be reported on every trial. This experiment tested observers in a task previously shown to produce an AB (e.g. The direct implication is that the ubiquitous tendency in past research to present stream items at or near 10 Hz may have masked the observation that the AB is enhanced by stimulus streams that are presented in the alpha-beta range (MacLean, Arnell, & Cote, 2012). With regard to the AB then, there appear to be two factors that may link second target accuracy to neural oscillations in the alpha-beta range: (1) the rate of the leading stream of items prior to the presentation of targets and (2) the observer’s level of engagement with first target processing. Moreover, when the observer is engaged in target detection processing, the brain appears to be driven to levels of higher alpha synchronization (Mima et al., 2001). Oscillations in the alpha range are especially important for perception (Hanslmayr, Gross, Klimesch, & Shapiro, 2011 Mathewson et al., 2012), with high amplitude alpha oscillation just prior to the onset of a stimulus associated with impaired target detection (Hanslmayr, Staudigl, & Klimesch, 2007).
It has long been known that brain oscillations play a crucial role in controlling the sleep–wakefulness cycle generally, and specifically, that they are relevant in guiding the timing of information processing (Buzsáki & Draguhn, 2004). Although historically these frequencies have been treated separately, recent EEG/MEG studies reveal that alpha (~10 Hz) and beta (~15 Hz) oscillations typically both decrease in amplitude during perception tasks, and that their dynamics are tightly correlated (Scheeringa et al., 2011). Here we show that the attentional blink is largest when the stimuli are presented in two neighbouring frequency bands alpha, the most dominant oscillatory frequency in the human brain (Berger, 1929), and beta, the nearby band whose effects often mirror it. Remarkably, virtually all of the hundreds of AB studies to date have embedded targets in a visual stream presented at approximately 10–16 Hz, placing it squarely in the oscillatory range of the alpha-beta complex (Scheeringa et al., 2011). Since its discovery, the AB has been replicated hundreds of times and is often-cited textbook knowledge.
This processing limitation is strikingly evident in the attentional blink task (AB Raymond et al., 1992), which reveals that only the first of the two targets reaches awareness unless they are separated by at least half a second.
One of the ubiquitous findings in cognitive psychology is that humans have severe difficulty processing two visual inputs in rapid succession.
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