Are spatial and temporal attention independent?

Participants searched for one of two target letters in a rapid serial visual presentation (RSVP) sequence of 17 successive frames, each containing four letters arranged into a box around a central fixation point. In control trial blocks, the participants had no information about when or where one of the target letters would appear. In other trial blocks, visual cues were given to indicate with 100% validity either the spatial location of the target, the time at which it would be presented, or both where and when it would appear. The results showed that both types of cues were effective on their own in speeding target identification, and their effects combined additively when the cues were presented and used together. These results support a growing body of evidence indicating that early attentional selection of information in vision is independently attuned to spatial and temporal properties of the environment.     

Alertness and cognitive control: Is there a spatial attention constraint?

Congruency effects in arrow flanker tasks are often larger when subjects are more alert, suggesting an unusual connection between alertness and cognitive control. Theoretical accounts of the alerting–congruency interaction differ with respect to whether and how spatial attention is involved. In the present study, the author conducted eight experiments to determine whether there is a spatial attention constraint linking alertness to cognitive control. Alertness was manipulated in color-word Stroop tasks involving stimuli that were spatially integrated (Experiments 1–3) or separated (Experiments 4 and 5), as well as in Stroop-like tasks involving spatially separated stimuli for which the irrelevant stimulus features were spatial words (Experiments 6 and 7) or arrows (Experiment 8). All experiments yielded effects of alerting and congruency, but none produced the alerting–congruency interaction typically found with arrow flanker tasks. The results suggest that there is a spatial attention constraint on the relationship between alertness and cognitive control, part of which might involve having a task goal associated with spatial information processing.     

When do microsaccades follow spatial attention?

Following up on an exchange about the relation between microsaccades and spatial attention (Horowitz, Fencsik, Fine, Yurgenson, & Wolfe, 2007; Horowitz, Fine, Fencsik, Yurgenson, & Wolfe, 2007; Laubrock, Engbert, Rolfs, & Kliegl, 2007), we examine the effects of selection criteria and response modality. We show that for Posner cuing with saccadic responses, microsaccades go with attention in at least 75% of cases (almost 90% if probability matching is assumed) when they are first (or only) microsaccades in the cue—target interval and when they occur between 200 and 400 msec after the cue. The relation between spatial attention and the direction of microsaccades drops to chance level for unselected microsaccades collected during manual-response conditions. Analyses of data from four cross-modal cuing experiments demonstrate an above-chance, intermediate link for visual cues, but no systematic relation for auditory cues. Thus, the link between spatial attention and direction of microsaccades depends on the experimental condition and time of occurrence, but it can be very strong.     

Grounding Perceptual Dogmatism: What are Perceptual Seemings?

Perceptual Dogmatism (PD) holds that if it perceptually seems to S that p, then S has immediate prima facie justification for the belief that p. Various philosophers have made the notion of a perceptual seeming more precise by distinguishing perceptual seemings from both sensations and beliefs to accommodate a) the epistemic difference between perceptual judgments of novices and experts, and, b) the problem of the speckled hen. Using somewhat different terminology, perceptual seemings are supposed to be high‐level percepts instead of low‐level sensations. I argue that although it is right that perceptual seemings should not be identified with sensations, they should also not be identified with percepts. There is no strong reason to assume that sensations and percepts exist as separate conscious states, and it appears therefore best to identify perceptual seemings simply with perceptual experiences interpreted as entities incorporating aspects from both sensations and percepts. However, even with this plausible identification in hand, the speckled hen will remain problematic for PD.     

Are spatial selection and identity extraction separable when attention is controlled endogenously?

Visual search for a target involves two processes: spatial selection and identity extraction. Ghorashi, Enns, and Di Lollo (2008) found these processes to be independent and surmised that they were carried out along distinct visual pathways: dorsal and ventral, respectively. The two experiments that are described in the present article evaluated this hypothesis. Attentional-blink methodology was combined with voluntary spatial cuing in a visual search task: Intertarget lag was used to manipulate identity extraction; predictive cues were used to signal target locations. Central digit cues in Experiment 1 required participants to identify digits before voluntarily directing attention to a corresponding location, whereas flashed dots in Experiment 2 (indicating an opposite location) required attentional redeployment without prior cue identification. Consistent with the dual-pathway hypothesis, cuing was impaired only when the first target and the number cue competed for ventral-pathway mechanisms. Collectively, the results support the dual-pathway account of the separability of spatial selection and identity extraction.     

Seeing or hearing? Perceptual independence,modality confusions,and crossmodal congruity effects with focused and divided attention

Observers were given brief presentations of pairs of simultaneous stimuli consisting of a visual and a spoken letter. In the visual focused-attention conditon, only the visual letter should be reported; in the auditory focused-attention condition, only the spoken letter should be reported; in the divided-attention condition, both letters, as well as their respective modalities, should be reported (forced choice). The proportions of correct reports were nearly the same in the three conditions (no significant divided-attention decrement), and in the divided-attention condition, the probability that the visual letter was correctly reported was independent of whether the auditory letter was correctly reported. However, with a probability much higher than chance, the observers reported hearing the visual stimulus letter or seeing the spoken stimulus letter (modality confusions). The strength of the effect was nearly the same with focused as with divided attention. We also discovered a crossmodal congruity effect: Performance was better when the two letters in a stimulus pair were the same than when they differed in type.     

Are spatial and dimensional attention separate? Evidence from Posner,Stroop, and Eriksen tasks

Do various operational definitions of visual attention tap the same underlying process? To address this question, we probed visual selective attention using orientation of attention, flanker, and Stroop tasks. These were embedded in combined designs that enabled assessment of each effect, as well as their interaction. For the orientation task, performance was poorer at unexpected than at expected locations. The flanker effects also differed across the two locations. In contrast, the Stroop effects were comparable at expected and unexpected locations. We conclude that spatial attention (tapped by the orientation and the flanker tasks) and dimensional attention (tapped by the Stroop task) engage separate processes of visual selection, both of which are needed in normal attention processing.     

Distracted and confused?: selective attention under load

The ability to remain focused on goal-relevant stimuli in the presence of potentially interfering distractors is crucial for any coherent cognitive function. However, simply instructing people to ignore goal-irrelevant stimuli is not sufficient for preventing their processing. Recent research reveals that distractor processing depends critically on the level and type of load involved in the processing of goal-relevant information. Whereas high perceptual load can eliminate distractor processing, high load on "frontal" cognitive control processes increases distractor processing. These findings provide a resolution to the long-standing early and late selection debate within a load theory of attention that accommodates behavioural and neuroimaging data within a framework that integrates attention research with executive function.     

Perceptual and motor inhibition of return: components or flavors?

The most common evidence for inhibition of return (IOR) is the robust finding of increased response times to targets that appear at previously cued locations following a cue?Ctarget interval exceeding ~300?ms. In a variation on this paradigm, Abrams and Dobkin (Journal of Experimental Psychology: Human Perception and Performance 20:467?C477, 1994b) observed that IOR was greater when measured with a saccadic response to a peripheral target than with that to a central arrow, leading to the conclusion that saccadic responses to peripheral targets comprise motoric and perceptual components (the two-components theory for saccadic IOR), whereas saccadic responses to a central target comprise a single motoric component. In contrast, Taylor and Klein (Journal of Experimental Psychology: Human Perception and Performance 26:1639?C1656, 2000) discovered that IOR for saccadic responses was equivalent for central and peripheral targets, suggesting a single motoric effect under these conditions. Rooted in methodological differences between the studies, three possible explanations for this discrepancy can be found in the literature. Here, we demonstrate that the empirical discrepancy is rooted in the following methodological difference: Whereas Abrams and Dobkin (Journal of Experimental Psychology: Human Perception and Performance 20:467?C477, 1994b) administered central arrow and peripheral onset targets in separate blocks, Taylor and Klein (Journal of Experimental Psychology: Human Perception and Performance 26:1639?C1656, 2000) randomly intermixed these stimuli in a single block. Our results demonstrate that (1) blocking central arrow targets fosters a spatial attentional control setting that allows for the long-lasting IOR normally generated by irrelevant peripheral cues to be filtered and (2) repeated sensory stimulation has no direct effect on the magnitude of IOR measured by saccadic responses to targets presented about 1?s after a peripheral cue.     

Cueing the location of a distractor: an inhibitory mechanism of spatial attention?

Presenting an irrelevant distractor increases reaction times to a target. The current study shows that cueing the location of an upcoming 'distractor' can help to reduce the effects the distractor has on target processing. It is hypothesized that this reduction is due to the active inhibition of the cued location. In two experiments in which the location of the distractor was cued in advance, a reduced effect of the distractor on target-processing was observed. Analyses indicated that this effect was most likely caused by inhibition of the distractor location. The present findings suggest that inhibition plays an important role in visual-spatial selection processes and that this inhibitory mechanism can be controlled in a top-down fashion.     

Does visual experience influence the spatial distribution of auditory attention?

Sighted individuals are less accurate and slower to localize sounds coming from the peripheral space than sounds coming from the frontal space. This specific bias in favour of the frontal auditory space seems reduced in early blind individuals, who are particularly better than sighted individuals at localizing sounds coming from the peripheral space. Currently, it is not clear to what extent this bias in the auditory space is a general phenomenon or if it applies only to spatial processing (i.e. sound localization). In our approach we compared the performance of early blind participants with that of sighted subjects during a frequency discrimination task with sounds originating either from frontal or peripheral locations. Results showed that early blind participants discriminated faster than sighted subjects both peripheral and frontal sounds. In addition, sighted subjects were faster at discriminating frontal sounds than peripheral ones, whereas early blind participants showed equal discrimination speed for frontal and peripheral sounds. We conclude that the spatial bias observed in sighted subjects reflects an unbalance in the spatial distribution of auditory attention resources that is induced by visual experience.     

Predicting attention and avoidance: When do avoiders attend?

Three avoidance measures, the Miller Behavioural Style Scale (MBSS), Index of Self-Regulation of Emotion (ISE) and Mainz Coping Inventory (MCI), were compared in their ability to predict attention and avoidance of threats in the emotional Stroop task. It was also examined if the avoidance mechanism of individuals who would normally avoid threat-indicating words becomes disrupted under conditions of dopamine reduction. Results show that only the ISE predicted attention/avoidance of threat-indicating words. In addition, the avoidance mechanism, as measured by the ISE and MCI, was not activated when regular smokers abstained from smoking.     

Modularity and attention: Is the binding problem real?

Abstract

Van der Heijden rejects the feature integration theory of visual attention (Treisman, 1988, 1993; Treisman & Gelade, 1980) and proposes instead a theory relating modularity in the visual system to selection for action. His positive proposals about the relations between visual processing, intention, and selection for action are interesting, but I do not believe they are incompatible with my theory. In this paper I will focus on and question his arguments about the binding problem and the role of attention in visual perception. Van der Heijden attacks two claims that are fundamental to my theory: (1) the idea that modularity gives rise to a “binding problem” (the need to specify which of the features present characterize any particular object), and (2) the more general idea that there are limits to capacity at the level of perceptual processing. I will argue that he is wrong to reject the two claims, that the binding problem is a real one, for his model as for others, and that his account is more similar to mine than he appears to realize.     

Is the exogenous orienting of spatial attention truly automatic? Evidence from unimodal and multisensory studies

The last decade has seen great progress in the study of the nature of crossmodal links in exogenous and endogenous spatial attention (see [Spence, C., McDonald, J., & Driver, J. (2004). Exogenous spatial cuing studies of human crossmodal attention and multisensory integration. In C. Spence, & J. Driver (Eds.), Crossmodal space and crossmodal attention (pp. 277-320). Oxford, UK: Oxford University Press.], for a recent review). A growing body of research now highlights the existence of robust crossmodal links between auditory, visual, and tactile spatial attention. However, until recently, studies of exogenous and endogenous attention have proceeded relatively independently. In daily life, however, these two forms of attentional orienting continuously compete for the control of our attentional resources, and ultimately, our awareness. It is therefore critical to try and understand how exogenous and endogenous attention interact in both the unimodal context of the laboratory and the multisensory contexts that are more representative of everyday life. To date, progress in understanding the interaction between these two forms of orienting has primarily come from unimodal studies of visual attention. We therefore start by summarizing what has been learned from this large body of empirical research, before going on to review more recent studies that have started to investigate the interaction between endogenous and exogenous orienting in a multisensory setting. We also discuss the evidence suggesting that exogenous spatial orienting is not truly automatic, at least when assessed in a crossmodal context. Several possible models describing the interaction between endogenous and exogenous orienting are outlined and then evaluated in terms of the extant data.     

Does gaze direction really trigger a reflexive shift of spatial attention?

Previous studies have found that the gaze direction of a centrally presented face facilitates response time (RT) to a lone peripheral target. The widely accepted interpretation of this finding is that gaze direction triggers a cortically mediated reflexive shift of spatial attention. In the present study we tested an alternative explanation, that a target appearing abruptly on its own in the visual field triggers a subcortically mediated reflexive shift of spatial attention, which is modulated by compatibility with gaze direction. Using central gaze cues, we compared RT to a single peripheral onset target with RT to a peripheral onset target accompanied by an equivalent distractor at the mirror opposite location. In both cases the facilitation effect was the same, demonstrating conclusively that the observed orienting is attributable to the reflexive effects of the gaze cue.     

Posterior parietal cortex: An interface between attention and learning?

The posterior parietal cortex (PPC) of rats has most recently been defined based on patterns of thalamic and cortical connectivity. The anatomical characteristics of this area suggest that it may be homologous to the PPC of primates and contribute to similar functions. This review summarizes evidence for and against a role for the rat PPC in attention and working memory and evaluates how the function of the rat PPC compares to that of primates on these dimensions. Theories of how the rat PPC contributes to behavior are presented, including the notion that PPC may serve as an interface between attention and learning. Finally, several avenues for future research are considered.     

Divided attention during encoding and retrieval: differential control effects?

Previous studies have shown that divided attention (DA) during retrieval has little effect on recall of episodic memories, although DA during encoding has a large detrimental effect. One possible reason for this asymmetry is that stimulus presentation at encoding is under experimenter control, whereas retrieval operations and responses are under participant control. This experiment tested this possibility by presenting paired-associate word lists for learning and recall, either at a fixed 4-s rate or at a rate controlled by the participant. The results showed that the higher recall levels for DA at retrieval than for DA at encoding held under all combinations of experimenter and participant control. The implications of these results for a fuller understanding of encoding and retrieval processes are discussed.     

Object-based attention: Shifting or uncertainty?

The contribution of object-based attentional guidance to visual processing is widely accepted, and recent models of attentional selection now include both space- and object-based representations. Nevertheless, although the mechanism of space-based attentional selection has been well characterized, the mechanism underlying object-based attentional selection remains poorly understood. Recent attempts at identifying the mechanism giving rise to object-based attentional selection have put forth two conflicting alternatives. The first suggests that object-based effects are driven by attentional uncertainty (i.e., the attentional prioritization hypothesis), whereas the second suggests that objects guide attentional selection only when an attentional shift is necessitated (i.e., the attentional-shifting hypothesis). Here, we directly investigated which of the two suggested accounts drives object-based effects, by pitting attentional certainty against attentional shifting. In a series of four experiments, we manipulated the certainty of target location, shifting of attention, and the stimulus onset asynchrony. It was observed that object-based effects depended solely on certainty of the forthcoming target location. These results suggest that attentional prioritization, and not a mere shift of attention, gives rise to object-based guidance of attentional selection. In addition, these results lend further support to the attentional prioritization account of object-based attention and provide further constraints on the mechanisms of object-based selection.     

Visual spatial constancy and modularity: Does intention penetrate vision?

Is vision informationally encapsulated from cognition or is it cognitively penetrated? I shall argue that intentions penetrate vision in the experience of visual spatial constancy: the world appears to be spatially stable despite our frequent eye movements. I explicate the nature of this experience and critically examine and extend current neurobiological accounts of spatial constancy, emphasizing the central role of motor signals in computing such constancy. I then provide a stringent condition for failure of informational encapsulation that emphasizes a computational condition for cognitive penetration: cognition must serve as an informational resource for visual computation. This requires proposals regarding semantic information transfer, a crucial issue in any model of informational encapsulation. I then argue that intention provides an informational resource for computation of visual spatial constancy. Hence, intention penetrates vision.