Exogenous Orienting Research Articles

The Frontal Cortex and Exogenous Attentional Orienting

Normal functioning of the attentional orienting system is critical for effective behavior and is predicated on a balanced interaction between goal-directed (endogenous) processes and stimulus-driven (exogenous) processes. Although both systems have been subject to much investigation, little is known about the neural underpinnings of exogenous orienting. In the present study, we examined the early facilitatory effects and later inhibition of return effects of exogenous cues in patients with frontal and parietal lesions. Three novel findings emerged from this study. First, unilateral frontoparietal damage appears not to affect the early facilitation effects of exogenous cues. Second, dorsolateral prefrontal damage, especially lesions involving the inferior frontal gyrus, produces an exogenous disengage deficit (i.e., the sluggish withdrawal of attention from the ipsilesional to the contralesional field). Third, a subset of patients with dorsolateral prefrontal damage, with lesions involving the middle frontal gyrus, have a reorienting deficit that extends in duration well beyond established boundaries of the normal reflexive orienting system. These results suggest that the dorsolateral prefrontal cortex plays an important role in exogenous orienting and that component processes of this system may be differentially impaired by damage to different parts of the dorsolateral prefrontal cortex.

Exogenous and Endogenous Attention Orienting in Autism Spectrum Disorders

Fifteen children with high-functioning Autism Spectrum Disorder (ASD) and 15 children with typical development completed an attentional cuing task using peripheral cues (exogenous orienting) and central cues (endogenous orienting). Results showed that participants with ASD had impaired exogenous and intact endogenous orienting. The pattern of exogenous orienting was related to motor functioning. Individuals with ASD who had poor motor functioning displayed slowed exogenous orienting. However, individuals with ASD who had relatively good motor functioning showed typical levels of exogenous orienting when given a short time but decreased orienting when given a longer amount of time. These results suggest attention impairments in ASD may not be specific to social orienting and instead may represent a more general orienting impairment.

Dissociating inhibition of return from endogenous orienting of spatial attention: Evidence from detection and discrimination tasks

In the present series of experiments, peripheral informative cues were used in order to dissociate endogenous and exogenous orienting of spatial attention using the same set of stimuli. For each block of trials, the cue predicted either the same or the opposite location of target appearance. Crucially, using this manipulation, both expected and unexpected locations could be either cued or uncued. If one accepts the hypothesis that inhibition of return (IOR) is an attentional effect that inhibits the returning of attention to a previously attended location (Posner & Cohen, 1984), one would not predict an IOR effect at the expected location, since attention should not disengage from the location predicted by the cue. Detection and discrimination tasks were used to examine any potential difference in the mechanism responsible for IOR as a function of the task at hand. Two major results emerged: First, IOR was consistently observed at the expected location, where, according to the traditional “reorienting” hypothesis, IOR is not supposed to occur. Second, a different time course of cueing effects was found in detection versus discrimination tasks, even after controlling for the orienting of attention. We conclude that IOR cannot be accounted for solely by the “reorienting of attention” hypothesis. Moreover, we argue that the observed time course differences in cueing effects between detection and discrimination tasks cannot be explained by attention disengaging from cues later in discrimination than in detection tasks, as proposed by Klein (2000). The described endogenous–exogenous dissociation is consistent with models postulating that endogenous and exogenous attentional processes rely on different neural mechanisms.

The multimodal world of medical monitoring displays

A vision of the future of intraoperative monitoring for anesthesia is presented—a multimodal world based on advanced sensing capabilities. I explore progress towards this vision, outlining the general nature of the anesthetist's monitoring task and the dangers of attentional capture. Research in attention indicates different kinds of attentional control, such as endogenous and exogenous orienting, which are critical to how awareness of patient state is maintained, but which may work differently across different modalities. Four kinds of medical monitoring displays are surveyed: (1) integrated visual displays, (2) head-mounted displays, (3) advanced auditory displays and (4) auditory alarms. Achievements and challenges in each area are outlined. In future research, we should focus more clearly on identifying anesthetists’ information needs and we should develop models of attention in different modalities and across different modalities that are more capable of guiding design.

Training Perceptual Skill by Orienting Visual Attention

A major element in expert sports performance, particularly racket-and-ball games, is excellent anticipatory skill. A prestudy combined the temporal and spatial occlusion paradigms to ascertain which key stimuli badminton players use for anticipating the direction of overhead shots. The main study then evaluated a program for training anticipatory skills; 200 video clips were employed to orient attention toward these key stimuli. Participants were 63 badminton novices, 20 national league players, and 21 local league players. A transparent red patch (exogenous orienting) was used to orient attention toward the trunk up to 160 ms before racket-shuttle contact; the arm, from 160 ms to 80 ms before contact; and the racket, from 80 ms before to actual contact. Results showed that badminton novices who trained with this program significantly improved their anticipatory skill between post- and retention test compared with controls. Whereas local league players improved from pre- to posttest, training had no effect on expert national league players. It is concluded that using red transparent patches to highlight the most informative cues in perceptual training programs is a promising way to improve anticipatory skill.

ERP and fMRI correlates of endogenous and exogenous focusing of visual‐spatial attention

The aim of this study was to investigate the neural correlates of the functional distinction underlying attentional mechanisms of endogenous-sustained and exogenous-transient spatial selection. We recorded event related potentials (ERPs) and used functional magnetic resonance imaging (fMRI) in separate experiments while subjects performed a simple reaction time (RT) to the same visual stimulus displayed to one of several field locations. Endogenous-sustained or exogenous-transient focusing of attention onto target location were obtained by presenting the stimulus in blocks of same-point vs. randomised-point trials, respectively. Same-point stimuli yielded overall faster RT than randomised stimuli, indicating a facilitating effect of endogenous-sustained spatial attention on the perceptual processing of the impending stimulus. Moreover, same-point vs. randomised presentations revealed significant increases in the fMRI signal in the bilateral lingual and fusiform gyri as well as in the right calcarine sulcus, in conjunction with a larger amplitude of the posterior P1 component of ERPs, but no modulation of the amplitude of the N1 component. Rather, a larger amplitude of N1 was found in the reverse contrast, randomised minus same-point trials, which revealed increases in the fMRI signal along the posterior left superior frontal sulcus and bilaterally in the superior precuneus. These findings indicate that N1 indexes exogenous orienting of attention and is likely to represent the activity of frontal and parietal components of the attention network involved in eliciting attention changes. In contrast, the effects of those changes, resulting in a modulation of activation in visual occipital areas, are indexed by P1.

Spatial attention triggered by unimodal, crossmodal, and bimodal exogenous cues: a comparison of reflexive orienting mechanisms

The aim of this study was to establish whether spatial attention triggered by bimodal exogenous cues acts differently as compared to unimodal and crossmodal exogenous cues due to crossmodal integration. In order to investigate this issue, we examined cuing effects in discrimination tasks and compared these effects in a condition wherein a visual target was preceded by both visual and auditory exogenous cues delivered simultaneously at the same side (bimodal cue), with conditions wherein the visual target was preceded by either a visual (unimodal cue) or an auditory cue (crossmodal cue). The results of two experiments revealed that cuing effects on RTs in these three conditions with an SOA of 200 ms had comparable magnitudes. Differences at a longer SOA of 600 ms (inhibition of return for bimodal cues, Experiment 1) disappeared when catch trials were included (in Experiment 2). The current data do not support an additional influence of crossmodal integration on exogenous orienting, but are well in agreement with the existence of a supramodal spatial attention module that allocates attentional resources towards stimulated locations for different sensory modalities.

The spatial correspondence hypothesis and orienting in response to central and peripheral spatial cues

Two experiments examined visual orienting in response to spatial precues. In Experiment 1A participants were informed that targets usually (p =.8) appeared on the same side as cues in a particular colour (e.g., red). Rapid orienting was observed, with both central and peripherally presented cues. In Experiment IB cue displays were spatially symmetric. Participants were informed that target location (left or right) was usually predicted (p =.8) by cue colour (red or green). Orienting effects were observed, but these were slower to develop and much weaker than in Experiment 1 A. In Experiment 2A and 2B the cue was a single, centrally presented letter. We compared effects of spatially symmetric (T, X, v, o) and asymmetric (d, b) letter cues. Validity effects were present for asymmetric cues, but entirely absent for symmetric cues. These finding are discussed in terms of Lambert and Duddy's (2002) proposal that spatial correspondence learning plays a critical role in spatial precueing. Implications of the results for the distinction between endogenous and exogenous orienting are also considered.

Considering phasic alerting in Alzheimer's disease: Comment on Tales et al. (2006).

A. Tales, R. J. Snowden, M. Brown, and G. Wilcock (2006) have questioned the authors' view of a possible interdependence between attentional systems mediating exogenous spatial orienting and phasic alerting as well as the authors' suggestion that phasic alerting deficits in patients with Alzheimer's disease (AD) may be influencing their performance on tests of spatial orienting. Consistent with this possibility, both laboratories have previously demonstrated increased spatial orienting and decreased phasic alerting in patients with AD. In Tales et al.'s current study, however, they have instead suggested that their results provide evidence for functional independence between these attentional systems in AD. In this commentary, the authors address the misinterpretations of their study and evaluate the degree to which Tales et al.'s study addresses the issues that they raise. Given Tales et al.'s difficulty performing analyses on response time data because of variance issues, the presence of a reduced (although not significant) alerting effect in Tales et al.'s AD group (consistent with the authors' previous findings), and a potential floor effect in their measure of alerting, the authors question the validity of Tales et al.'s conclusions and reaffirm their position that not considering interactions among attentional systems can lead to inaccurate characterizations of the mechanisms by which they operate.

Sex differences in eye gaze and symbolic cueing of attention

Observing a face with averted eyes results in a reflexive shift of attention to the gazed-at location. Here we present results that show that this effect is weaker in males than in females (Experiment 1). This result is predicted by the 'extreme male brain' theory of autism (Baron-Cohen, 2003), which suggests that males in the normal population should display more autism-like traits than females (e.g., poor joint attention). Indeed, participants' scores on the Autism-Spectrum Quotient (Baron-Cohen, Wheelwright, Stott, Bolton, & Goodyear, 2001) negatively correlated with cueing magnitude. Furthermore, exogenous orienting did not differ between the sexes in two peripheral cueing experiments (Experiments 2a and 2b). However, a final experiment showed that using nonpredictive arrows instead of eyes as a central cue also revealed a large gender difference. This demonstrates that reduced orienting from central cues in males generalizes beyond gaze cues. These results show that while peripheral cueing is equivalent in the male and female brains, the attention systems of the two sexes treat noninformative symbolic cues very differently.

Two electrophysiological stages of spatial orienting towards fearful faces: early temporo-parietal activation preceding gain control in extrastriate visual cortex

Visuo-spatial attention tends to be prioritized towards emotionally negative stimuli such as fearful faces, as opposed to neutral or positive stimuli. Using a covert orienting task, we previously showed that a lateral occipital P1 component, with extrastriate neural sources, was selectively enhanced to lateralized visual targets replacing a fearful face (fear-valid trial) than the same targets replacing a neutral face (fear-invalid trial), providing evidence for exogenous spatial orienting of attention towards threat cues. Here, we describe a new analysis of these data, using topographic evoked potentials mapping methods combined with a distributed source localization technique. We show that an early field topography (40–80 ms post-target onset) with a centro-parietal negativity and a left posterior parietal source distinguished fear-valid from fear-invalid trials, whereas a distinct activity with anterior cingulate sources was selectively evoked during fear-invalid trials. At the same latency, or later, no difference in field topography was found for valid compared to invalid trials with happy faces. The early parietal map preceded a modulation in amplitude of the field strength (∼130ms), corresponding to the enhanced lateral occipital P1 during valid trials in the fear condition. Furthermore, this early topography at 40–80 ms was positively correlated with the subsequent amplitude modulation of P1 at 130–160 ms in the fear condition, suggesting a possible functional coupling between these two successive events. These data have important implications for models of spatial attention and interactions with emotion. They suggest two successive stages of neural activity during exogenous orienting of attention towards visual targets following fearful faces, including an early posterior parietal negativity, followed by gain control mechanisms enhancing visual responses in extrastriate occipital cortex.

Competition Between Endogenous and Exogenous Orienting of Visual Attention.

The relation between reflexive and voluntary orienting of visual attention was investigated with 4 experiments: a simple detection task, a localization task, a saccade toward the target task, and a target identification task in which discrimination difficulty was manipulated. Endogenous and exogenous orienting cues were presented in each trial and their validity was manipulated orthogonally to examine whether attention mechanisms are mediated by separate systems and whether they have additive and independent effects on visual detection and discrimination. The results showed that each orienting mechanism developed its typical and independent effect in every case except for the difficult identification task. A theoretical framework for understanding the relationship between endogenous and exogenous orienting of attention is proposed, tested, and confirmed.

Speed-Accuracy Tradeoff Operator Characteristics of Endogenous and Exogenous Covert Orienting of Attention

There is debate over the mechanisms that govern the orienting of attention. Some argue that the enhanced performance observed at a cued location is the result of increased perceptual sensitivity or preferential access to decision-making processes. It has also been suggested that these effects may be the result of trades in speed for accuracy on the part of the observers. In the present study, observers performed either an exogenous or an endogenous orienting of attention task under both normal instructions (respond as quickly and as accurately as possible) and speeded instructions that used a deadline procedure to limit the amount of time observers had to complete a choice reaction time (CRT) task. An examination of the speed-accuracy operating characteristics (SAOCs) yielded evidence against the notion that CRT precuing effects are due primarily to a tradeoff of accuracy for speed.

Neural networks underlying endogenous and exogenous visual–spatial orienting

The orienting of visual-spatial attention is fundamental to most organisms and is controlled through external (exogenous) or internal (endogenous) processes. Exogenous orienting is considered to be reflexive and automatic, whereas endogenous orienting refers to the purposeful allocation of attentional resources to a predetermined location in space. Although behavioral, electrophysiological and lesion research in both primates and humans suggests that separate neural systems control these different modes of orienting, previous human neuroimaging studies have largely reported common neuronal substrates. Therefore, event-related FMRI (ER-FMRI) was used to independently examine different components of the orienting response including endogenous facilitation, exogenous facilitation and inhibition of return (IOR). In contrast to previous studies, endogenous versus exogenous facilitation resulted in widespread cortical activation including bilateral temporoparietal junction, bilateral superior temporal gyrus, right middle temporal gyrus, right frontal eye field and left intraparietal sulcus. Conversely, IOR compared to endogenous facilitation resulted in only a single focus of activation in the left superior temporal gyrus. These findings suggest that endogenous orienting activates a large cortical network to achieve internally generated shifts of attentional resources versus the automatic orienting that occurs with exogenous cues. However, similar networks may mediate endogenous orienting and IOR. The activation of the temporoparietal junction suggests that it is involved in more effortful processes, such as endogenous orienting, as well as in attentional reorienting and locating targets. Current results are discussed in terms of the functional development of the visual-spatial attentional system.

Exogenous Orienting of Attention Depends upon the Ability to Execute Eye Movements

Shifts of attention can be made overtly by moving the eyes or covertly with attention being allocated to a region of space that does not correspond to the current direction of gaze. However, the precise relationship between eye movements and the covert orienting of attention remains controversial. The influential premotor theory [1, 2] proposes that the covert orienting of attention is produced by the programming of (unexecuted) eye movements and thus predicts a strong relationship between the ability to execute eye movements and the operation of spatial attention. Here, we demonstrate for the first time that impaired spatial attention is observed in an individual (AI) who is neurologically healthy but who cannot execute eye movements as a result of a congenital impairment in the elasticity of her eye muscles [4–6]. This finding provides direct support for the role of the eye-movement system in the covert orienting of attention and suggests that whereas intact cortical structures may be necessary for normal attentional reflexes, they are not sufficient. The ability to move our eyes is essential for the development of normal patterns of spatial attention.

Endogenous and exogenous attention shifts are mediated by the same large-scale neural network

Event-related fMRI was used to examine the neural basis of endogenous (top-down) and exogenous (bottom-up) spatial orienting. Shifts of attention were induced by central (endogenous) or peripheral (exogenous) cues. Reaction times on subsequently presented targets showed the expected pattern of facilitation and inhibition in both conditions. No difference in brain activity was observed when the two orienting conditions were contrasted with a liberal threshold, showing that both forms of orienting were mediated by the same neural network. Compared to within-block control trials, both endogenous and exogenous orienting activated a fronto-parietal network consisting of premotor cortex, posterior parietal cortex, medial frontal cortex and right inferior frontal cortex. Within these regions, equally strong activation was observed for both orienting conditions. It is concluded that endogenous and exogenous orienting are mediated by the same large-scale network of frontal and parietal brain areas.

Crossmodal attention between vision and touch in temporal order judgment task

Four experiments investigated the effects of cross-modal attention between vision and touch in temporal order judgment tasks combined with spatial cueing paradigm. In Experiment 1, two vibrotactile stimuli with simultaneous or successive onsets were presented bimanually to the left and right index fingers and participants were asked to judge the temporal order of the two stimuli. The tactile stimuli were preceded by a spatially uninformative visual cue. Results indicated that shift of spatial attention yielded by visual cueing resulted in the modulation of accuracy of the subsequent tactile temporal order judgment. However, this cueing effect disappeared when participants judged simultaneity of the two stimuli, instead of their temporal order (Experiment 2) or when the cue lead time between the visual cue and the stimuli was relatively long (Experiment 3). Experiment 4 replicated an effect of crossmodal attention on the direction of visual illusory line motion induced by a somatosensory cue (Shimojo, Miyauchi, & Hikosaka, 1997). These results demonstrate that substantial crossmodal links exist between vision and touch for covert exogenous orienting of attention.

Relative Color Contrast Drives Competition in Early Exogenous Orienting.

Young infants typically orient to a moving object, but the strength of this tendency depends on what else is in the visual field, with some objects competing for attention more effectively than others. This competition was studied in 3.5-month-old infants by manipulating the colors and spatial distributions of static elements that appeared with a small moving probe. The hypothesis was that the competition from these static bars would depend on their color contrasts. Three different color pairings were used: red with green, pink with green, and red with pink. The results were generally consistent with the hypothesis that the competition from static elements in the visual field depends on their color contrasts. Orienting at 3.5 months is determined by competition mechanisms that weight motion and color and most probably other stimulus characteristics to produce a directional response.

The development of exogenous orienting: mechanisms of control

The present study examined exogenous orienting in children ages 6 years ( n=14), 10 years ( n=13), 14 years ( n=14), and adults ( n=13). The main purpose was to identify which of the attentional operations underlying exogenous orienting (disengaging, shifting, and/or engaging) improves with age. A simple detection task was used in which single targets were correctly (80%) or incorrectly (20%) cued. The main finding was that disengaging attention alone distinguished the performance of younger children from that of older children and adults, regardless of whether attention alone (covert attention) or attention and associated sensory and motor systems (overt attention) were involved. In addition, our data, in contrast to those reported previously, raise the possibility that even the youngest children tested were able to use the predictability of the cue to enhance their performance. These and related neuroanatomical findings are taken as evidence for the development with age of more flexible control in orienting visual attention.

Spotlight failure effect in exogenous orienting

Many experimental results about spatial attention have been explained by assuming the existence of an attentional “spotlight” which can move from one location in visual space to another. Such an account has been recently challenged by findings which show the influence of nonspatial factors in spatial attention. In particular, the so-called “spotlight failure” effect refers to the influence of the probability of occurrence of different stimuli. However, such an effect has only been reported in the case of endogenous (or central) orientation, rather than on exogenous (or peripheral) orienting. We present evidence showing that the spotlight failure effect can be obtained with exogenous orienting, even at a short SOA (100 ms). Besides, experimental instructions can modulate the effect, which agrees with theoretical accounts proposing that top-down factors can influence attentional capture.