Separate mechanisms recruited by exogenous and endogenous spatial cues: Evidence from a spatial Stroop paradigm.

The present experiments tested whether endogenous and exogenous cues produce separate effects on target processing. In Experiment 1, participants discriminated whether an arrow presented left or right of fixation pointed to the left or right. For 1 group, the arrow was preceded by a peripheral noninformative cue. For the other group, the arrow was preceded by a central, symbolic, informative cue. The 2 types of cues modulated the spatial Stroop effect in opposite ways, with endogenous cues producing larger spatial Stroop effects for valid trials and exogenous cues producing smaller spatial Stroop effects for valid trials. In Experiments 2A and 2B, the influence of peripheral noninformative and peripheral informative cues on the spatial Stroop effect was directly compared. The spatial Stroop effect was smaller for valid than for invalid trials for both types of cues. These results point to a distinction between the influence of central and peripheral attentional cues on performance and are not consistent with a unitary view of endogenous and exogenous attention. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attentional components of partial report.

In 8 bar-probe, partial-report experiments, performance declined as the duration of the cue increased. This effect obtained with peripheral but not central cues occurred even when cues are uninformative and was not found when the cue required some interpretation. Results suggest that the effect of cue duration is related to the exogenous attentional system and is not found when the endogenous attentional system is used exclusively. Results also suggest that long-duration cues do not interfere with shifts of attention and that local contour proximity is neither necessary nor sufficient to produce the effect. It is hypothesized that long-duration cues generate interference because they direct attention to a period of time when the decaying visual representation of the array is unreliable. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

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. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Capture of attention in selective frequency listening.

Four signal-detection experiments demonstrated robust stimulus-driven, or exogenous, attentional processes in selective frequency listening. Detection of just-above-threshold signal tones was consistently better when the signal matched the frequency of an uninformative cue tone, even with relatively long cue-signal delays (Experiment 1) or when as few as 1 in 8 signals were at the cued frequency (Experiment 2). Experiments 3 and 4 compared performance with informative and uninformative cues. The involvement of intentional, or endogenous, processes was found to only slightly increase the size of the cuing effect beyond that evident with solely exogenous processes, although the attention band, a measure of how narrowly attention is focused, was found to be wider when cues were informative. The implications for models of auditory attention are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Simon effect with and without awareness of the accessory stimulus.

The authors investigated whether a Simon effect could be observed in an accessory-stimulus Simon task when participants were unaware of the task-irrelevant accessory cue. In Experiment 1A a central visual target was accompanied by a suprathreshold visual lateral cue. A regular Simon effect (i.e., faster cue-response corresponding reaction times [RTs]) was found. Experiment 1B demonstrated that this effect cannot be attributed to perceptual grouping of the target and cue. Experiments 2A, 2B, and 2C showed a reverse Simon effect (i.e., faster noncorresponding RTs) when participants were not aware of the cue. In this condition, the Simon effect would occur relative to the reorientation of attention from the cue, which would initially capture attention, toward the target. This conclusion is supported by the results of Experiments 3A and 3B, in which the reorientation of attention was induced by having the target flash after its onset. With suprathreshold cues either a reverse or regular Simon effect was observed by using a 100-ms or ≥200-ms onset flashing interval, respectively, whereas with subthreshold cues a reverse Simon effect was found irrespective of the interval length. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A new component of visual orienting: Implicit effects of peripheral information and subthreshold cues on covert attention.

Four experiments examined effects of peripheral cue stimuli on covert spatial attention. In Experiment 1 target stimuli were preceded by a pair of bilaterally presented cue letters. The relative location of the cues predicted target location (left or right), but participants were not informed of this. After a brief practice period, visual orienting was influenced by the letter cues. This implicit peripheral cuing effect was unrelated to participants' awareness of the cue-target relationship. Experiments 2 and 3 showed that visual orienting may occur independently of both perceptual awareness of the peripheral cue event itself and contingency awareness concerning the cue–target relation. Experiment 4 demonstrated that implicit peripheral cuing is qualitatively distinct from voluntary orienting. These findings are discussed in relation to work on spatial attention, implicit learning, and perception without awareness. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Interactive Activation in Visual Word Recognition: Constraints Imposed by the Joint Effects of Spatial Attention and Semantics.

Two lexical-decision experiments investigated the effects of semantic priming and stimulus intensity when target location varied and was cued by an abrupt onset. In Experiment 1, the spatial cue was a good predictor of target location, and in Experiment 2 it was not. The results indicate that word recognition processes were postponed until spatial attention was focused on the target and that whether attention further affected word recognition depended on cue validity. The joint effects of cue validity and priming interacted when cue validity was high but were additive when cue validity was low. The joint effects of stimulus intensity and semantic priming also varied according to cue validity (i.e., interactive when high and additive when low). The results are discussed in terms of their implications for visual word recognition, the distinction between exogenous and endogenous spatial attention, and how attention is affected by visual word recognition processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On the uniqueness of attentional capture by uninformative gaze cues: Facilitation interacts with the Simon effect and is rarely followed by IOR.

Orienting to an uninformative peripheral cue is characterized by a brief facilitation followed by a long-lasting inhibition once attention is removed from the cued location. Although central gaze cues cause reflexive orienting, the inhibitory effect that is relatively ubiquitous following exogenous orienting to uninformative peripheral cues has been relatively rare. We hypothesized that IOR might be seen following gaze-induced orienting if attention were effectively returned to centre by a return gaze or return flash. The timecourse of gaze-directed orienting was measured by varying the interval between the gaze cue and a peripheral target requiring an orientation discrimination (permitting measurement of the Simon effect). Significant facilitation was observed at all but the longest SOA tested, 2,880 ms, by which time the facilitation had disappeared with no evidence of IOR. Gaze-induced cuing (which was unaffected by return cue condition) interacted with the Simon effect, decreasing it at the gazed-at location, a pattern that is not seen with more typical endogenous and exogenous cuing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Competition between endogenous and exogenous attention to nonemotional stimuli in social anxiety.

This study investigated whether impaired endogenous attention and enhanced exogenous attention for the processing of nonemotional stimuli were observed in individuals with high social anxiety. In each trial, participants were presented with an endogenous cue at a center, followed by exogenous cues at peripheral locations; subsequently, nonemotional masked targets were presented wherein the subjects were asked to distinguish between the targets. The accuracy rates were influenced by social anxiety only in exogenous conditions. Individuals with high social anxiety exhibited higher accuracy in the valid condition than in the invalid condition of exogenous attention, whereas individuals with low social anxiety displayed uniform accuracy rates in valid, neutral, and invalid conditions. The validity effects in individuals with high social anxiety did not diminish when controlling for trait and state anxiety and depression. The results suggest that individuals with high social anxiety have an enhanced exogenous attentional system and that they are attracted to salient stimuli regardless of emotionality. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visuospatial attention is guided by both the symbolic value and the spatial proximity of selected arrows.

There is considerable evidence that overlearned symbols, especially arrows, can orient attention to peripheral locations. In 2003, Pratt and Hommel showed that when 1 arrow is selected from a set of arrows, based on an attentional control setting for a specific target color, the selected arrow determines the orientation of attention. Recently, Leblanc and Jolicoeur (2010) reexamined this finding, and concluded that spatial proximity of the arrow to the target, not the symbolic value of the arrow, determines the orienting of attention. Here, we manipulated both the symbolic value of the cue (direction arrows or directionless circles) and the proximity of the cue to the peripheral target location (near or far), and found that although proximity does play a role in the orienting of attention (larger cuing effects were found with far cues than near cues), the symbolic content of the cue also plays an important role (larger cuing effects were found with arrows than circles). Thus, both the symbolic value and the spatial proximity of cues affect the orienting of attention. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Is Posner's "beam" the same as Treisman's "glue?" On the relation between visual orienting and feature integration theory.

In the present study we investigated whether the visually allocated "beam" studied by Posner and others is the same visual attentional resource that performs the role of feature integration in Treisman's model. Subjects were cued to attend to a certain spatial location by a visual cue, and performance at expected and unexpected stimulus locations was compared. Subjects searched for a target letter (R) with distractor letters that either could give rise to illusory conjunctions (PQ) or could not (PB). Results from three separate experiments showed that orienting attention in response to central cues (endogenous orienting) showed similar effects for both conjunction and feature search. However, when attention was oriented with peripheral visual cues (exogenous orienting), conjunction search showed larger effects of attention than did feature search. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Enhanced facilitation of spatial attention in schizophrenia.

Objective: While attentional functions are usually found to be impaired in schizophrenia, a review of the literature on the orienting of spatial attention in schizophrenia suggested that voluntary attentional orienting in response to a valid cue might be paradoxically enhanced. We tested this hypothesis with orienting tasks involving the cued detection of a laterally presented target stimulus. Method: Subjects were chronic schizophrenia patients (SZ) and matched healthy control subjects (HC). In Experiment 1 (15 SZ, 16 HC), cues were endogenous (arrows) and could be valid (100% predictive) or neutral with respect to the subsequent target position. In Experiment 2 (16 SZ, 16 HC), subjects performed a standard orienting task with unpredictive exogenous cues (brightening of the target boxes). Results: In Experiment 1, SZ showed a larger attentional facilitation effect on reaction time than HC. In Experiment 2, no clear sign of enhanced attentional facilitation was found in SZ. Conclusions: The voluntary, facilitatory shifting of spatial attention may be relatively enhanced in individuals with schizophrenia in comparison to healthy individuals. This effect bears resemblance to other relative enhancements of information processing in schizophrenia such as saccade speed and semantic priming. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Aging and shifts of visual spatial attention.

Three experiments examined adult age differences in the efficiency of endogenous (voluntary) and exogenous (involuntary) attention shifts. Younger and older Ss performed a spatial cuing task in which abruptly onset peripheral cues (Exp 1) or central, symbolic cues (Exps 2 and 3) were presented before a target stimulus at intervals ranging from 50 to 250 msec. With peripheral cues, the magnitude of cuing effects was at least as great for older as for younger adults and followed a similar time course. Similar results were obtained with symbolic cues, although cuing effects for older adults varied with cue difficulty. The results suggest that cue encoding may decline with advancing age but that the efficiency of the shift process is preserved. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A unique role of endogenous visual-spatial attention in rapid processing of multiple targets.

Visual spatial attention can be exogenously captured by a salient stimulus or can be endogenously allocated by voluntary effort. Whether these two attention modes serve distinctive functions is debated, but for processing of single targets the literature suggests superiority of exogenous attention (it is faster acting and serves more functions). We report that endogenous attention uniquely contributes to processing of multiple targets. For speeded visual discrimination, response times are faster for multiple redundant targets than for single targets because of probability summation and/or signal integration. This redundancy gain was unaffected when attention was exogenously diverted from the targets but was completely eliminated when attention was endogenously diverted. This was not a result of weaker manipulation of exogenous attention because our exogenous and endogenous cues similarly affected overall response times. Thus, whereas exogenous attention is superior for processing single targets, endogenous attention plays a unique role in allocating resources crucial for rapid concurrent processing of multiple targets. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

How attentional systems process conflicting cues. The superiority of social over symbolic orienting revisited.

We investigated orienting of attention by social and symbolic cues presented inside/outside the locus of attention. Participants responded to laterally presented targets preceded by simultaneously presented gaze and arrow cues. Participants’ attention was allocated to either of the cues and the other cue served as a distractor. In Experiments 1–4 nonpredictive cues were employed. The validity of the attended cue and distractor were varied orthogonally. Valid cues and distractors produced additive facilitation to reaction times when compared to invalid cues and distractors. The effects of gaze and arrow distractors were similar. When the cue was 100% valid and the distractor 50% valid (Experiment 5), distractor validity had no effect on reaction times. When realistic gaze and arrow cues were employed (Experiment 6), arrow but not gaze distractors influenced the reaction times. The results suggest that social and symbolic directional information can be integrated for attention orienting. The processing of social and symbolic directional information can be modulated by top-down control, but the efficiency of the control depends on the visual saliency of the cues. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sound affects the speed of visual processing.

The authors examined the effects of a task-irrelevant sound on visual processing. Participants were presented with revolving clocks at or around central fixation and reported the hand position of a target clock at the time an exogenous cue (1 clock turning red) or an endogenous cue (a line pointing toward 1 of the clocks) was presented. A spatially irrelevant sound presented 100 ms before the cue speeded visual latency when compared with a sound presented 100 ms after the cue. The effect of the sound was larger the farther the target was from fixation, and it was larger for endogenous than exogenous cues. A visual temporal warning signal had different effects on perceptual latency. These results demonstrate that an asynchronous sound can shift the perceived time of occurrence of a visual cue (temporal ventriloquism) and speed the velocity of the attentional shift toward the target. Sounds thus have multiple effects on visual perception. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Auditory and visual capture during focused visual attention.

It is well known that auditory and visual onsets presented at a particular location can capture a person’s visual attention. However, the question of whether such attentional capture disappears when attention is focused endogenously beforehand has not yet been answered. Moreover, previous studies have not differentiated between capture by onsets presented at a nontarget (invalid) location and possible performance benefits occurring when the target location is (validly) cued. In this study, the authors modulated the degree of attentional focus by presenting endogenous cues with varying reliability and by displaying placeholders indicating the precise areas where the target stimuli could occur. By using not only valid and invalid exogenous cues but also neutral cues that provide temporal but no spatial information, they found performance benefits as well as costs when attention is not strongly focused. The benefits disappear when the attentional focus is increased. These results indicate that there is bottom-up capture of visual attention by irrelevant auditory and visual stimuli that cannot be suppressed by top-down attentional control. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Emotional scene content drives the saccade generation system reflexively.

The authors assessed whether parafoveal perception of emotional content influences saccade programming. In Experiment 1, paired emotional and neutral scenes were presented to parafoveal vision. Participants performed voluntary saccades toward either of the scenes according to an imperative signal (color cue). Saccadic reaction times were faster when the cue pointed toward the emotional picture rather than toward the neutral picture. Experiment 2 replicated these findings with a reflexive saccade task, in which abrupt luminosity changes were used as exogenous saccade cues. In Experiment 3, participants performed vertical reflexive saccades that were orthogonal to the emotional–neutral picture locations. Saccade endpoints and trajectories deviated away from the visual field in which the emotional scenes were presented. Experiment 4 showed that computationally modeled visual saliency does not vary as a function of scene content and that inversion abolishes the rapid orienting toward the emotional scenes. Visual confounds cannot thus explain the results. The authors conclude that early saccade target selection and execution processes are automatically influenced by emotional picture content. This reveals processing of meaningful scene content prior to overt attention to the stimulus. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perceptual-motor expectancies interact with covert visual orienting under conditions of endogenous but not exogenous control.

Investigated whether the interaction between endogenous cueing and stimulus/response (S/R) would be obtained if attention was controlled exogenously, using 16 Ss. Central and peripheral cues were used to endogenously or exogenously direct the S's attention to the location at which an increase or decrease in the size of a peripheral object was most likely to occur. For each S, one size change was more likely to occur than the other, and the task was choice reaction time (RT; expansion/contraction). S/R probability (particular size change) interacted with cue condition (valid, neutral, and invalid) when the cues were central (endogenous), but the 2 variables were additive when the cues were peripheral (exogenous). Data suggest that controlled allocation of attention in response to a peripheral cue involves qualitatively different mechanisms from those associated with endogenous generation of an expectancy. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Switching in the cocktail party: Exploring intentional control of auditory selective attention.

Using a novel variant of dichotic selective listening, we examined the control of auditory selective attention. In our task, subjects had to respond selectively to one of two simultaneously presented auditory stimuli (number words), always spoken by a female and a male speaker, by performing a numerical size categorization. The gender of the task-relevant speaker could change, as indicated by a visual cue prior to auditory stimulus onset. Three experiments show clear performance costs with instructed attention switches. Experiment 2 varied the cuing interval to examine advance preparation for an attention switch. Experiment 3 additionally isolated auditory switch costs from visual cue priming by using two cues for each gender, so that gender repetition could be indicated by a changed cue. Experiment 2 showed that switch costs decreased with prolonged cuing intervals, but Experiment 3 revealed that preparation did not affect auditory switch costs but only visual cue priming. Moreover, incongruent numerical categories in competing auditory stimuli produced interference and substantially increased error rates, suggesting continued processing of task-relevant information that often leads to responding to the incorrect auditory source. Together, the data show clear limitations in advance preparation of auditory attention switches and suggest a considerable degree of inertia in intentional control of auditory selection criteria. (PsycINFO Database Record (c) 2011 APA, all rights reserved)