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.     

Visual field asymmetries in attention vary with self-reported attention deficits

The purpose of this study was to determine whether an index of self-reported attention deficits predicts the pattern of visual field asymmetries observed in behavioral measures of attention. Studies of “normal” subjects do not present a consistent pattern of asymmetry in attention functions, with some studies showing better left visual field (LVF) performance, others showing no asymmetry or even a right visual field (RVF) advantage. Here we found that a participant variable (a measure of self-reported attention problems) may help to explain these inconsistencies. We used Conners’ Adult ADHD Rating Scales to measure self-reported attention problems in a group of 36 normal (non-ADHD) subjects, and we used two behavioral tasks to directly measure their attentional abilities: a lateralized Attention Network Task (ANT) and a visual search task. Comparing subjects with relatively Low versus High scores on the attention-deficit (AD) scale, we found that subjects with High scores were less efficient in orienting attention to the left visual field. When LVF targets were preceded by a valid spatial cue, response times were positively correlated with AD scores, indicating slower covert-attention shifts as attention-deficit scores increased. Right visual field data showed a different pattern of results. Subjects with High AD scores were at least as efficient as those with Low AD scores in orienting attention to the RVF. This study provides evidence that visual field asymmetries in orienting attention vary across individuals, and that level of self-reported attention problems correlates with behavioral deficiencies in orienting attention to the left visual field.     

The cost of action miscues: hemispheric asymmetries

Adaptive behaviors require preparation and when necessary inhibition or alteration of actions. The right hemisphere has been posited to be dominant for preparatory motor activation. This experiment was designed to learn if there are hemispheric asymmetries in the control of altered plans of actions. Cues, both valid and invalid, which indicate the hand most likely to be called onto respond, as well as the imperative stimuli that indicate the actual response hand, were presented to either the right or left visual fields of 14 normal right handed participants. The delay after a miscue is dependent on the time taken to inhibit the premotor and motor systems of the incorrectly activated hemisphere, as well as to activate the motor systems of the opposite hemisphere, which might have been interhemispherically inhibited by this miscue. Analyses of reaction times revealed that miscues presented in left hemispace (right hemisphere) cost more time than those miscues presented in right hemispace (left hemisphere), suggesting that activation of the preparatory systems controlled by the right hemisphere may take longer to reverse than those controlled by the left hemisphere. This asymmetry may be related to asymmetries in the strength of hemispheric activation with contralateral inhibition.     

The direction of hemispheric asymmetries for object categorization at different levels of abstraction depends on the task

In this study hemispheric asymmetries for categorizing objects at the basic versus subordinate level of abstraction were investigated. As predictions derived from different theoretical approaches are contradictory and experimental evidence is inconclusive in this regard, we conducted two categorization experiments, where we contrasted two experimental paradigms. In the first experiment, subjects had to verify whether a word and a laterally presented picture matched or not. In the second experiment, subjects had to identify laterally presented pictures of animals either at the basic or subordinate level by pressing a corresponding response key. Whereas the first experiment revealed an advantage of the left hemisphere (LH) for categorizing objects at the basic level and of the right hemisphere (RH) for categorizing at the subordinate level, just the opposite brain asymmetry was found in the second experiment. As the stimuli were identical in both experiments, hemispheric asymmetries seem to be strongly task dependent.     

Emotional and hemispheric asymmetries in shifts of attention: An ERP study

Inhibition of return (IOR) refers to the larger response time to cued targets appearing at long cue-to-target intervals. Given emotion–attention interactions and associated visual field (VF) asymmetries, we examined the effects of emotions and hemispheric processing on object- and location-based IOR. We expected reduced IOR and right hemispheric bias accompanied by differences in event-related potentials (ERPs) including lack of suppression of cued N1 and enhancement of Nd components for sad targets. Reaction times and ERPs were recorded in an exogenous cuing detection task using happy and sad schematic faces. Results revealed reduced IOR for left compared to right VF with sad faces but no such asymmetry for happy faces. Cued N1 amplitudes were suppressed for happy targets but not for sad targets presented to the left VF. Nd amplitudes were enhanced for right-hemispheric sad faces especially with object-based IOR. The results indicate right-hemispheric advantage in the capture of attention by negative emotion especially with object-based selection.     

The Contribution of Attention to the Right Visual Field Advantage for Word Recognition

Perceptual asymmetries have been explained by structural, attentional bias and attentional advantage models. Structural models focus on asymmetries in the physical access information has to the hemispheres, whereas attentional models focus on asymmetries in the operation of attentional processes. A series of experiments was conducted to assess the contribution of attentional mechanisms to the right visual field (RVF) advantage found for word recognition. Valid, invalid and neutral peripheral cues were presented at a variety of stimulus onset asynchronies to manipulate spatial attention. Results indicated a significant RVF advantage and cueing effect. The effect of the cue was stronger for the left visual field than the RVF. This interaction supports the attentional advantage model which suggests that the left hemisphere requires less attention to process words. The attentional asymmetry is interpreted in terms of the different word processing styles used by the left and right hemispheres. These results have ramifications for the methodology used in divided visual field research and the interpretation of this research.     

Hemispheric differences in the interference among components of compound gratings

The relationship between local/global and high/low spatial-frequency processing in hemispheric asymmetries was explored. Subjects were required to judge the orientation of a high- or low-spatial-frequency component of a compound grating presented in the left visual field (LVF) or right visual field (RVF). In Experiment 1, attention was focused on one or the other component. A signal detection analysis indicated that sensitivity (d′) to the high-spatial-frequency target was reduced more by the presence of the low-spatial-frequency component when both were presented in the LVF rather than in the RVF. In Experiment 2, subjects determined whether a target orientation was present, independent of spatial frequency at only a single level (i.e., at the high- or low-spatial-frequency level), as opposed to both or neither level. An RVF/LH (left hemisphere) advantage was found when the decision was based on the orientation of the high-frequency component. The asymmetrical influence of visual field of presentation and spatial frequency upon sensitivity is discussed in terms of hemispheric differences in the magnitude of inhibition between spatial-frequency channels and in the role of transient channel activity to capture and direct higher order attentional processes.     

Age-related differences in attentional networks of alerting and executive control in young, middle-aged, and older Chinese adults

Previous studies suggest that aging is associated with impairment of attention. However, it is not known whether this represents a global attentional deficit or relates to a specific attentional network. We used the attention network test to examine three groups of younger, middle-aged, and older participants with respect to the efficiency of three anatomically defined attentional networks: alerting network, orienting network, and executive control network. Age-related change was found to have the greatest effect on the executive network and the least effect on the alerting network as well as on overall mean response time. Impairment of the orienting network was found to be insignificant. Age-related deterioration of the prefrontal lobe, the dopaminergic system, and function of specific genes may explain the age-related changes in executive attention, which occur after the fourth decade of life.     

A left hemisphere, but not right hemispace, advantage for tactual simultaneity judgments

Hemispheric asymmetries for tactile simultaneity judgments were investigated in 34 dextral adults. Pairs of vibrotactile stimuli with simultaneous or successive onsets were delivered unilaterally to the left or right hand. Participants made a forced-choice, bipedal response, indicating whether a stimulus was simultaneous or successive. The effect of hemispatial attentional biases was investigated, using ipsilateral (arms uncrossed) and contralateral (arms crossed) hand placements. Trials presented to the right hand were associated with fewer errors and a trend for faster response times than were those presented to the left hand. There was no asymmetry in response bias. Manipulations of hemispace did not affect the right hand advantage. These results confirm the existence of a left hemisphere temporal-processing advantage but fail to demonstrate that the asymmetry is the result of a rightward attentional bias. The implications of these results for absolute and relative models of hemispheric specialization are discussed.     

Automatic attention lateral asymmetry in visual discrimination tasks

There is evidence that automatic visual attention favors the right side. This study investigated whether this lateral asymmetry interacts with the right hemisphere dominance for visual location processing and left hemisphere dominance for visual shape processing. Volunteers were tested in a location discrimination task and a shape discrimination task. The target stimuli (S2) could occur in the left or right hemifield. They were preceded by an ipsilateral, contralateral or bilateral prime stimulus (S1). The attentional effect produced by the right S1 was larger than that produced by the left S1. This lateral asymmetry was similar between the two tasks suggesting that the hemispheric asymmetries of visual mechanisms do not contribute to it. The finding that it was basically due to a longer reaction time to the left S2 than to the right S2 for the contralateral S1 condition suggests that the inhibitory component of attention is laterally asymmetric.     

Focus on the positive: Anxiety modulates the effects of emotional stimuli on hemispheric attention

People with high levels of trait anxiety are said to orient attention selectively to threatening stimuli ( and ), but this effect is sometimes difficult to replicate. We suggest a reason for this difficulty is that typical tests of the spatial attention bias in anxiety failed to consider together: (1) the differential effects of positive and threatening stimuli on attention in anxiety, (2) the separate contributions of each hemisphere to the attention bias, and (3) whether the attention bias in anxiety is restricted to orienting or can be observed more strongly in the conflict or alerting networks of attention. We compared the effects of schematic angry, happy, and neutral face cues using a lateralized version of Posner’s Attention Network Task (Lateralized Attention Network Test) which distinguishes spatial Orienting Cost (due to an invalid cue; disengagement) from spatial Orienting Benefit (due to a valid cue; hypervigilance), and which considers executive Conflict resolution and Alerting in addition to spatial Orienting in each hemisphere separately. We tested participants with high and low trait anxiety measured by the STAI-TA (Spielberger, Gorsuch, & Lushene, 1983). Surprisingly, happy face cues rather than angry face cues interacted with target visual field and participant level of anxiety. Happy face cues presented to participants with low anxiety elicited maximal Orienting Benefit and minimal Orienting Cost for targets presented to the left visual field. Anxious individuals failed to benefit from happy cues in the left visual field. We suggest that lateralized positive cues can provide a more sensitive index of attention changes in anxiety than is provided by centrally-presented threatening cues.     

French adaptation of the Attentional Control Scale: Confirmatory factor analyses and relationship with trait anxiety and efficiency of orienting,alerting, and executive control attentional networks

BackgroundThe Attentional Control Scale (ACS) is a self-report questionnaire that measures individual differences in attentional control.ObjectiveThis study compared four models of the French version of the ACS and examined its links to trait anxiety and three attentional networks (orienting, alerting, and executive control) measured with the Attention Network Test (ANT).ResultsConfirmatory analyses conducted with a sample of 284 university students supported a two-factor (focusing and shifting) model. For 59 participants who completed the ANT, we found a positive correlation between focusing and the executive control network, while shifting was negatively correlated with alerting and orienting. Trait anxiety was negatively correlated with focusing and the alerting and executive control networks.ConclusionResults are discussed with a view to improving the assessment of attentional control, a key executive dimension for emotion regulation and attentional disengagement in anxiety.     

Dysfunction of attentional networks for non-emotional processing in negative affect

It is unclear whether negative affect is associated with the impairment of attentional networks for non-emotional processing. Using the attention network test (ANT), which assesses the efficiency of alerting, orienting, and executive attention, we attempted to clarify which attentional networks were related to negative affect, i.e., anxiety, depression, and social anxiety. Forty-three participants completed the self-report questionnaires and the ANT. Negative affect was negatively correlated with orienting efficiency but not executive attention. Our results indicate that people with negative emotionality have an impaired orienting network for non-emotional stimuli. It is suggested that attentional bias for threatening stimuli in negative affect is due to the original impairment of the orienting network.     

Both sides get the point: Hemispheric sensitivities to sentential constraint

Behavioral studies have consistently reported striking differences in the impact of sentence-level information on the processing of words presented in the right (RVF) versus the left (LVF) visual field, with context effects apparent only for RVF items. The consistent lack of such effects in the LVF has been taken to mean that right hemisphere language comprehension is largely insensitive to message-level meaning. We used the functional specificity afforded by event-related potential measures to assess this claim. Target words completing strongly and weakly constraining sentence contexts, in which constraint arose at the sentence level rather than from lexical associations, were presented laterally in the LVF or RVF. Increased constraint significantly reduced N400 amplitudes with presentation in both VFs, with no differences in the timing or amplitude of these effects. These results are inconsistent with the view that the VF asymmetries found in behavioral measures reflect differential hemispheric capacities at the level of semantic analysis and integration, although VF-based differences on earlier components (P2) suggest asymmetries in the impact of sentential context on perceptual aspects of word processing in the two hemispheres.     

Effects of chewing on cognitive processing speed

In recent years, chewing has been discussed as producing effects of maintaining and sustaining cognitive performance. We have reported that chewing may improve or recover the process of working memory; however, the mechanisms underlying these phenomena are still to be elucidated. We investigated the effect of chewing on aspects of attention and cognitive processing speed, testing the hypothesis that this effect induces higher cognitive performance. Seventeen healthy adults (20–34 years old) were studied during attention task with blood oxygenation level-dependent functional (fMRI) at 3.0 T MRI. The attentional network test (ANT) within a single task fMRI containing two cue conditions (no cue and center cue) and two target conditions (congruent and incongruent) was conducted to examine the efficiency of alerting and executive control. Participants were instructed to press a button with the right or left thumb according to the direction of a centrally presented arrow. Each participant underwent two back-to-back ANT sessions with or without chewing gum, odorless and tasteless to remove any effect other than chewing. Behavioral results showed that mean reaction time was significantly decreased during chewing condition, regardless of speed-accuracy trade-off, although there were no significant changes in behavioral effects (both alerting and conflict effects). On the other hand, fMRI analysis revealed higher activations in the anterior cingulate cortex and left frontal gyrus for the executive network and motor-related regions for both attentional networks during chewing condition. These results suggested that chewing induced an increase in the arousal level and alertness in addition to an effect on motor control and, as a consequence, these effects could lead to improvements in cognitive performance.     

Attention Network Performance and Psychopathic Symptoms in Early Adolescence: An ERP Study

Reaction time (RT) and event-related potential (ERP) measures were used to examine the relationships between psychopathic symptoms and three major attention networks (alerting, orienting, and executive attention) among a community sample of youth. Antisocial Process Screening Device (APSD; Frick and Hare 2001) total and subscale scores were negatively correlated with ERP measures of attentional alerting, indicating that youth with psychopathic symptoms had difficulty using warning cues to prepare for upcoming targets. APSD total scores were not related to performance on measures of orienting or executive attention, although weaker executive attention was found among youth with higher scores on the Impulsivity subscale. These findings support attention-based models of psychopathy and provide evidence of specific deficits in attentional alerting among youth with psychopathic traits. Deficiencies in attentional alerting may be related to noradrenergic functioning and may have cascading effects on higher order cognitive and affective processing.     

Hemisphere differences in the effects of cuing in visual recognition tasks.

In Experiment 1 uncued recognition of single letters presented in left or right visual fields showed no hemispheric asymmetry, but cuing by alternatives produced a left-hemisphere advantage. Uncued recognition of words was better in the right visual field (left hemisphere), and this advantage was unchanged by cuing by alternatives or cuing by class. In Experiment 2 a mixed series of words, digits, and dots was presented. Uncued trials showed no asymmetry, but when a precue indicated which type or stimulus would appear next, a left-hemisphere advantage for words was evident. Cuing also produced a nonsignificant shift toward a left-hemisphere advantage for digits and a right-hemisphere advantage for dots. The asymmetrical effects of cuing can be explained by Kinsbourne's attentional model of lateralization, which suggests that cuing may selectively activate one hemisphere, and so bias attention toward the contralateral visual field. Repetition effects within and between visual fields were analyzed but no asymmetries were found.     

Hemispheric differences in the perception of words and faces in deaf and hearing children

The purpose of this study was to investigate hemispheric functional asymmetry in 18 normal hearing children and 18 congenitally deaf children aged 13-14 years. The task was identification of a visual stimulus (3-letter word or photograph of a face) presented in either the left or right visual field. The children responded by pointing to the target stimulus on a response card which contained four different words or three different faces. The percentage of errors for presentations to the two visual fields were analysed to determine hemispheric dominance. The pattern of hemispheric differences for the hearing children was consistent with that from previous investigations. The results for the deaf children differed from those of the normals. In word perception we observed a right hemisphere advantage and in the face recognition a lack of hemispheric differences. These results point to a lack of auditory experiences which is affecting the functional organization of the two hemispheres. It is suggested that the necessity to make use of visuo-spatial information in the process of communication causes right hemisphere dominance in verbal tasks. This may influence the perception of other visuo-spatial stimuli which may yield a lack of hemispheric asymmetry in face recognition.     

Limits of control: The effects of uncontrollability experiences on the efficiency of attentional control

Two experiments were conducted to explore the effects of experiencing uncontrollability on the efficiency of attentional control. The experience of uncontrollability was induced either by unsolvable tasks (Experiment 1) or by tasks in which non-contingent feedback was provided (Experiment 2). A version of the Attentional Network Test-Interactions with an additional measure of vigilance (ANTI-V) was used to evaluate the efficiency of the attentional networks (i.e., alerting, orienting, and executive). Results of both experiments revealed a decreased efficiency of executive attention in participants who experienced stable control deprivation but no negative effects in participants who were able to restore their sense of previously deprived control. Additionally, when participants were asked to perform unsolvable tasks and did not receive feedback (Experiment 1), detrimental effects on the orienting network and vigilance were observed. The motivational and cognitive mechanisms underlying the effects of various uncontrollability experiences on conflict resolution and attentional control are discussed.     

Asymmetrical hemisphere activation enhances global–local processing

Decades of research focusing on the neurophysiological underpinnings related to global–local processing of hierarchical stimuli have associated global processing with the right hemisphere and local processing with the left hemisphere. The current experiment sought to expand this research by testing the causal contributions of hemisphere activation to global–local processing. To manipulate hemisphere activation, participants engaged in contralateral hand contractions. Then, EEG activity and attentional scope were measured. Right-hand contractions caused greater relative left-cortical activity than left-hand contractions. Participants were more narrowly focused after left-hemisphere activation than after right-hemisphere activation. Moreover, N1 amplitudes to local targets in the left hemisphere were larger after left-hemisphere activation than after right-hemisphere activation. Consistent with past research investigating hemispheric asymmetry and attentional scope, the current results suggest that manipulating left (right) hemisphere activity enhanced local (global) attentional processing.