Amir Raz

Testing the Efficiency and Independence of Attentional Networks

In recent years, three attentional networks have been defined in anatomical and functional terms. These functions involve alerting, orienting, and executive attention. Reaction time measures can be used to quantify the processing efficiency within each of these three networks. The Attention Network Test (ANT) is designed to evaluate alerting, orienting, and executive attention within a single 30-min testing session that can be easily performed by children, patients, and monkeys. A study with 40 normal adult subjects indicates that the ANT produces reliable single subject estimates of alerting, orienting, and executive function, and further suggests that the efficiencies of these three networks are uncorrelated. There are, however, some interactions in which alerting and orienting can modulate the degree of interference from flankers. This procedure may prove to be convenient and useful in evaluating attentional abnormalities associated with cases of brain injury, stroke, schizophrenia, and attention-deficit disorder. The ANT may also serve as an activation task for neuroimaging studies and as a phenotype for the study of the influence of genes on attentional networks.

Training the brain: fact and fad in cognitive and behavioral remediation.

Putatively safe and effective for improving cognitive performance in both health and disease, products purported to train the brain appeal to consumers and healthcare practitioners. In an increasingly health-centered society, these applications constitute a burgeoning commercial market. Sparse evidence coupled with lack of scientific rigor, however, leaves claims concerning the impact and duration of such brain training largely unsubstantiated. On the other hand, at least some scientific findings seem to support the effectiveness and sustainability of training for higher brain functions such as attention and working memory. In the present paper we provide a tectonic integration and synthesis of cognitive training approaches. Specifically, we sketch the relative merits and shortcomings of these programs, which often appeal to parents who must choose between side-effect-laden medication and other less conventional options. Here we examine how neuroplasticity allows the healthy as well the impaired to benefit from cognitive training programs. We evaluate the evidence and consider whether brain training can be a stand-alone treatment or an adjunct to pharmacotherapy, outline promising future prospects, and highlight what training outcomes are plausible in line with available data. Future research would determine whether the field of brain training realizes its potential to revolutionize education and rehabilitation or withers away engulfed in controversy.

Suggestion Reduces the Stroop Effect

We examined the effects of suggestion on Stroop interference in highly suggestible individuals. Participants completed the Stroop task with and without a suggestion to perceive Stroop words as meaningless symbols. Half the participants were given this suggestion in hypnosis, and half were given the suggestion without the induction of hypnosis. Suggestion produced a significant reduction in Stroop inhibition, accounting for about 45% of the variance in Stroop responding, regardless of whether hypnosis had been induced. These findings indicate that suggestion can at least partially overcome the automaticity associated with the Stroop effect.

Attention and Hypnosis: Neural Substrates and Genetic Associations of Two Converging Processes

Abstract Although attention is a central theme in psychological science, hypnosis researchers rarely incorporate attentional findings into their work. As with other biological systems, attention has a distinct anatomy that carries out basic psychological functions. Specific brain injuries, states, and drugs can all influence attentional networks. Investigation into these networks using modern neuroimaging techniques has revealed important mechanisms involved in attention. In this age of genomics, genetic approaches can supplement these neuroimaging techniques. As genotyping becomes an affordable and technologically viable complement to phenotyping, exploratory genetic assays offer insights into the genetic bases of both attention and hypnotizability. This paper discusses relevant aspects of attentional mechanisms and their underlying neuroanatomy as they relate to hypnosis. Underlining data from attentional networks, neuroimaging, and genetics, these findings should help to explain individual differences in hypnotizability and the neural systems subserving hypnosis. 1Selected themes and portions of this paper appear in German in the Jubilee edition of HyKog (Raz, Fossella, McGuiness, Zephrani, & Posner, in press) and in a book chapter (Raz, Fan, & Posner, in press).

Posthypnotic suggestion and the modulation of Stroop interference under cycloplegia

Recent data indicate that under a specific posthypnotic suggestion to circumvent reading, highly suggestible subjects successfully eliminated the Stroop interference effect. The present study examined whether an optical explanation (e.g., visual blurring or looking away) could account for this finding. Using cyclopentolate hydrochloride eye drops to pharmacologically prevent visual accommodation in all subjects, behavioral Stroop data were collected from six highly hypnotizables and six less suggestibles using an optical setup that guaranteed either sharply focused or blurred vision. The highly suggestibles performed the Stroop task when naturally vigilant, under posthypnotic suggestion not to read, and while visually blurred; the less suggestibles ran naturally vigilant, while looking away, and while visually blurred. Although visual accommodation was precluded for all subjects, posthypnotic suggestion effectively eliminated Stroop interference and was comparable to looking away in controls. These data strengthen the view that Stroop interference is neither robust nor inevitable and support the hypothesis that posthypnotic suggestion may exert a top-down influence on neural processing.

The self-regulating brain and neurofeedback: Experimental science and clinical promise

Neurofeedback, one of the primary examples of self-regulation, designates a collection of techniques that train the brain and help to improve its function. Since coming on the scene in the 1960s, electroencephalography-neurofeedback has become a treatment vehicle for a host of mental disorders; however, its clinical effectiveness remains controversial. Modern imaging technologies of the living human brain (e.g., real-time functional magnetic resonance imaging) and increasingly rigorous research protocols that utilize such methodologies begin to shed light on the underlying mechanisms that may facilitate more effective clinical applications. In this paper we focus on recent technological advances in the field of human brain imaging and discuss how these modern methods may influence the field of neurofeedback. Toward this end, we outline the state of the evidence and sketch out future directions to further explore the potential merits of this contentious therapeutic prospect.

Measuring attention in the hemispheres: The lateralized attention network test (LANT)

The attention network test (ANT) is a brief computerized battery measuring three independent behavioral components of attention: Conflict resolution (ability to overcome distracting stimuli), spatial Orienting (the benefit of valid spatial pre-cues), and Alerting (the benefit of temporal pre-cues). Imaging, clinical, and behavioral evidence demonstrate hemispheric asymmetries in these attentional networks. We constructed a lateralized version of the ANT (LANT), with brief targets flashed in one or the other visual hemifield. We also modified the tests by including invalid spatial cues in order to measure the cost component of Orienting. In a series of experiments, we investigated the efficiency of the attention networks separately in each hemisphere. Participants exhibited significant estimates of all networks measured by the LANT, comparable to the ANT. The three networks were represented in each hemisphere separately and were largely comparable across the two hemispheres. We suggest that the LANT is an informative extension of the original ANT, allowing for measurement of the three attention networks in each hemisphere separately.

Can suggestion obviate reading? Supplementing primary Stroop evidence with exploratory negative priming analyses

Using the Stroop paradigm, we have previously shown that a specific suggestion can remove or reduce involuntary conflict and alter information processing in highly suggestible individuals (HSIs). In the present study, we carefully matched less suggestible individuals (LSIs) to HSIs on a number of factors. We hypothesized that suggestion would influence HSIs more than LSIs and reduce the Stroop effect in the former group. As well, we conducted secondary post hoc analyses to examine negative priming (NP) - the apparent disruption of the response to a previously-ignored item. Our present findings indicate that suggestion reduces Stroop effects in HSIs. Secondary analyses show that LSIs had an NP effect at baseline (i.e., without suggestion) and that suggestion influenced the NP condition. Thus, at least in this experimental context, suggestion seems to dampen a deeply-engrained and largely automatic process - reading - by wielding a larger influence on HSIs relative to comparable LSIs.

Ecological nuances in functional magnetic resonance imaging (fMRI): psychological stressors, posture, and hydrostatics

Brain imaging techniques such as functional magnetic resonance imaging (fMRI) have forged an impressive link between psychology and neuroscience. Whereas most experiments in cognitive psychology require participants to perform while sitting upright in front of display devices, fMRI obliges participants to perform cognitive tasks while lying supine and motionless inside a narrow bore. In addition to introducing psychological and physical stressors, such as loud thumps and head restraints, fMRI procedures also alter brain hydrostatics. The ecological factors associated with current fMRI technology, such as supine posture, may skew cognitive processing and influence hemodynamic and electrophysiological measurements, especially in extreme age groups and pathological populations. Recognizing the central role of fMRI in unraveling the neural mechanisms of cognition, we outline ways to address these limitations.

Neuroimaging and genetic associations of attentional and hypnotic processes.

In the aftermath of the human genome project, genotyping is fast becoming an affordable and technologically viable complement to phenotyping. Whereas attempts to characterize hypnotic responsiveness have been largely phenomenological, data emanating from exploratory genetic data may offer supplementary insights into the genetic bases of hypnotizability. We outline our genetic and neuroimaging findings and discuss potential implications to top-down control systems. These results may explain individual differences in hypnotizability and propose new ideas for studying the influence of suggestion on neural systems.