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.     

Interaction between endogenous and exogenous orienting in crossmodal attention

Using a cue-target paradigm, we investigated the interaction between endogenous and exogenous orienting in cross-modal attention. A peripheral (exogenous) cue was presented after a central (endogenous) cue with a variable time interval. The endogenous and exogenous cues were presented in one sensory modality (auditory in Experiment 1 and visual in Experiment 2) whereas the target was presented in another modality. Both experiments showed a significant endogenous cuing effect (longer reaction times in the invalid condition than in the valid condition). However, exogenous cuing produced a facilitatory effect in both experiments in response to the target when endogenous cuing was valid, but it elicited a facilitatory effect in Experiment 1 and an inhibitory effect in Experiment 2 when endogenous cuing was invalid. These findings indicate that endogenous and exogenous cuing can co-operate in orienting attention to the crossmodal target. Moreover, the interaction between endogenous and exogenous orienting of attention is modulated by the modality between the cue and the target.     

Feature integration and spatial attention: common processes for endogenous and exogenous orienting

Briand (J Exp Psychol Hum Percept Perform 24:1243–1256, 1998) and Briand and Klein (J Exp Psychol Hum Percept Perform 13:228–241, 1987) demonstrated that spatial cueing effects are larger for detecting conjunction of features than for detecting simple features when spatial attention is oriented exogenously, and not when attention is oriented endogenously. Their results were interpreted as if only exogenous attention affects the posterior spatial attention system that performs the feature binding function attributed to spatial attention by Treisman’s feature integration theory (FIT; 1980). In a series of 6 experiments, we attempted to replicate Briand’s findings. Manipulations of distractor string size and symmetry of stimulus presentation left and right from fixation were implemented in Posner’s cueing paradigm. The data indicate that both exogenous and endogenous cueing address the same attentional mechanism needed for feature binding. The results also limit the generalisability of Briand’s proposal concerning the role of exogenous attention in feature integration. Furthermore, the importance to control the effect of unintended attentional capture in a cueing task is demonstrated.     

Modulation of object-based attention by spatial focus under endogenous and exogenous orienting

In R. Egly, J. Driver, and R. D. Rafal's (1994) influential double-rectangle spatial-cuing paradigm, exogenous cues consistently induce object-based attention, whereas endogenous cues generally induce space-based attention. This difference suggests an interdependency between mode of orienting (endogenous vs exogenous) and mode of selection (object based vs space based). However, mode of orienting is generally confounded with initial focus of attention: Endogenous orienting begins with attention focused on a central cue, whereas exogenous orienting begins with attention widely spread. In this study, an attentional-focusing hypothesis is examined and supported by experiments showing that for both endogenous and exogenous cuing, object-based effects are obtained under conditions that encourage spread attention, but they are attenuated under conditions that encourage focused attention. General implications for object-based attention are discussed. ((c) 2003 APA, all rights reserved)     

When endogenous spatial attention improves conscious perception: Effects of alerting and bottom-up activation

Recent studies have consistently demonstrated that conscious perception interacts with exogenous attentional orienting, but it can be dissociated from endogenous attentional orienting (Chica, Lasaponara, et al., 2011, Wyart and Tallon-Baudry, 2008). It has been hypothesized that enhanced conscious processing at exogenously attended locations results from a synergistic action of spatial orienting, bottom-up activation, and phasic alerting induced by the abrupt onset of the exogenous cue (Chica, Lasaponara, et al., 2011). Instead, as endogenous cues need more time to be interpreted, the phasic alerting they produce may have dissipated when the target appears. Furthermore, endogenous cues presumably elicit a weak bottom-up activation at the cued location. Consistent with these hypotheses, we observed that endogenous attention modulated conscious perception, but only when phasic alerting or bottom-up activation was increased. Results are discussed in the context of recent theoretical models of consciousness (Dehaene, Changeux, Naccache, Sackur, & Sergent, 2006).     

Object-based visual attention with endogenous orienting

In a series of experiments, we examined covert orienting using endogenous cuing, in which attention is voluntarily directed toward a peripheral location. In one experiment, subjects were cued to attend to one end of an oblong object. They then detected targets on the cued object or elsewhere. In another experiment, subjects provided judgments of the relative temporal order of two flashes after their attention had moved endogenously. In a third experiment, subjects were directed to attend to an empty spatial location and subsequently discriminated features of objects that appeared at or near the locus of attention. In each of these situations, attentional orienting was object based, in the sense that nonattended locations that were on the cued object had an advantage over nonattended locations that were not on the object. The results are discussed in terms of their implications for object-based representations and the differences between exogenous and endogenous orienting of attention.     

The hare and the snail: Dissociating visual orienting from conscious perception

A method for investigating attentional effects of peripheral visual objects, independently of perceptual identification, is described. We report an experiment using this method which shows that visual processing of peripheral objects differs radically, depending on whether participants move attention in response to an object or consciously perceive that object. When luminance contrast was reduced, conscious perceptual discrimination of peripheral letters was massively slower and less accurate—but both low and high contrast letters elicited rapid attentional orienting effects and these rapid orienting effects were equal in magnitude across low and high contrast. This pattern is consistent with known differences in luminance sensitivity between the dorsal and ventral visual processing streams, and with rapid dorsal–ventral interaction mediated via re-entrant feedback. Our findings show that the control system responsible for rapid movements of attention is exquisitely sensitive to visual form information at low levels of contrast, and involves a different neurocognitive pathway to that which gives rise to conscious perception.     

Assessing the automaticity of the exogenous orienting of tactile attention

We examined whether or not abrupt tactile onsets are capable of exogenously capturing tactile spatial attention when visual spatial attention is focused elsewhere. In experiment 1, we compared performance under dual-task conditions (where participants performed a tactile exogenous cuing task and a rapid serial visual presentation--RSVP--task at the same time) with their performance under single-task conditions (where the participants had to perform only the cuing task, although the RSVP stream was still presented in the background) and to a no-stream condition (where only the cuing task was presented). Tactile cuing was completely suppressed in both the dual-task and single-task conditions, showing that exogenous tactile spatial orienting is modulated by visual-spatial attention, which hence appears to be far from truly automatic. In experiment 2, we demonstrated that the abolishment of exogenous tactile orienting was not caused by the transient presentation of abrupt onset stimuli (letters). These results therefore show that exogenous spatial attentional orienting toward abrupt peripheral tactile stimuli is possible as long as perceptual resources are not depleted by a perceptually demanding (RSVP) task.     

Nonconscious perception, conscious awareness and attention

Because it is unclear how a nonconscious stimulus is cognitively processed, there is uncertainty concerning variables that modulate the processing. In this context recent findings of a set of neuroimaging experiments are important. These findings suggest that conscious and nonconscious stimuli activate same areas of the brain during performance of a similar task. Further, different areas are activated when a task is performed with or without awareness of processing. It appears that the neural network involved in cognitive processing depends on the awareness of processing rather than awareness of perception. Since conscious and nonconscious cognitive processing use separate neural networks, each processing is modulated by different variables. Attention modulates most conscious cognitive processing and most, but not all, nonconscious processing is attention dependent. Nonconscious tasks that require attentional resources, with or without conscious awareness, are processed using the attention dependent system. Further, because attention dependent and attention independent tasks are processed by separate neural networks, the cognitive processing and modulating variables can be understood better if cognitive tasks are defined as attention dependent or attention independent, rather than conscious or nonconscious.     

Spatial orienting of attention in stereo depth

The aim of this study was to investigate the spatial orienting of visual attention in depth under purely stereoscopic viewing conditions. Random-dot stereograms were used to present disparity-defined target stimuli that were either validly or invalidly cued in depth. In separate tasks, participants responded either to the relative depth of the target (protruding vs. receding) or to its shape (square vs. diamond). Stimulus onset asynchronies (SOAs) between an uninformative exogenous cue and target were varied from 250 to 600?ms. For both tasks, mean response times (RTs) were shorter for validly than invalidly cued target depths and this RT advantage was essentially restricted to the shortest SOA of 250?ms. These results indicate that attention can be reflexively allocated to locations in stereo depth under conditions of low perceptual load, and independent of whether depth is relevant to the task or not.     

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.     

The independence of endogenous and exogenous temporal attention

Temporal attention is the focusing of perceptual resources at a particular point in time. Valid temporal cue information has the capability to improve performance by reducing reaction times, while invalid information has the possibility of impairing performance. The performance difference between valid and invalid conditions is called a temporal cueing effect (TCE). We explored how different alerting mechanisms interact with a participant’s ability to utilize temporal information cues, using the Kingstone (The Quarterly Journal of Experimental Psychology, 44(1), 69–104, 1992) temporal cueing paradigm. Extracting the alerting procedure from Lawrence and Klein (Journal of Experimental Psychology: General, 142(2), 560–572, 2013), one of two different temporally contingent warning signals were presented to participants during a trial. The “hi-intensity” warning signal increases intensity and elicits both exogenous and endogenous alerting mechanisms. The “no-intensity” warning signal is isointense relative to baseline and elicits only endogenous alerting mechanisms. Two experiments conducted previously using a discrimination task showed interference between the signal intensity and task difficulty, where the “no-intensity” signal failed to elicit TCEs. In the present study, we implemented a detection task, reducing the mental effort required for a response. The results showed equal TCEs in both signal conditions. We argue for independence of these alerting mechanisms, by way of Sternberg’s (Acta Psychologica, 30, 276–315, 1969) additive factor method. Arguments contrasting what mechanism is being impacted by this paradigm are further outlined.     

Interactions between endogenous and exogenous attention during vigilance

The ability to remain vigilant over long periods of time is critical for many everyday tasks, but controlled studies of visual sustained attention show that performance declines over time when observers are required to respond to rare stimulus events (targets) occurring in a sequence of standard stimulus events (nontargets). When target discrimination is perceptually difficult, this vigilance decrement manifests as a decline in perceptual sensitivity. We examined whether sudden-onset stimuli could act as exogenous attentional cues to improve sensitivity during a traditional sustained attention task. Sudden-onset cues presented immediately before each stimulus attenuated the sensitivity decrement, but only when stimulus timing (the interstimulus interval [ISI]) was constant. When stimulus timing was variable, exogenous cues increased overall sensitivity but did not prevent performance decline. Finally, independent of the effects of sudden onsets, a constant ISI improved vigilance performance. Our results demonstrate that exogenous attention enhances perceptual sensitivity during vigilance performance, but that this effect is dependent on observers’ being able to predict the timing of stimulus events. Such a result indicates a strong interaction between endogenous and exogenous attention during vigilance. We relate our findings to a resource model of vigilance, as well as to theories of endogenous and exogenous attention over short time periods.     

内外源性空间注意对多感觉整合的影响

本文采用内-外源性空间线索靶子范式, 操控内源性线索有效性(有效线索、无效线索)、外源性线索有效性(有效线索、无效线索)、目标刺激类型(视觉刺激、听觉刺激、视听觉刺激)三个自变量。通过两个不同任务难度的实验(实验1: 简单定位任务; 实验2: 复杂辨别任务)来考察内外源性空间注意对多感觉整合的影响。两个实验结果均发现外源性空间注意显著减弱了多感觉整合效应, 内源性空间注意没有显著增强多感觉整合效应; 实验2中还发现了内源性空间注意会对外源性空间注意减弱多感觉整合效应产生影响。结果表明, 与内源性空间注意不同, 外源性空间注意对多感觉整合的影响不易受任务难度的调控; 当任务较难时内源性空间注意会影响外源性空间注意减弱多感觉整合效应的过程。由此推测, 内外源性空间注意对多感觉整合的调节并非彼此独立、而是相互影响的。     

Spatial orienting of tactile attention induced by social cues

Several studies have established that humans orient their visual attention reflexively in response to social cues such as the direction of someone else’s gaze. However, the consequences of this kind of orienting have been addressed only for the visual system. We investigated whether visual social attention cues can induce shifts in tactile attention by combining a central noninformative eye-gaze cue with tactile targets presented to participants’ fingertips. Data from speeded detection, speeded discrimination, and signal detection tasks converged on the same conclusion: Eye-gaze-based orienting facilitates the processing of tactile targets at the location of the gazed-at body location. In addition, we examined the effects of other directional cues, such as conventional arrows, and found that they can be equally effective. This is the first demonstration that social attention cues have consequences that reach beyond their own sensory modality.