When cross-modal spatial attention fails.

There is now convincing evidence that an involuntary shift of spatial attention to a stimulus in one modality can affect the processing of stimuli in other modalities, but inconsistent findings across different paradigms have led to controversy. Such inconsistencies have important implications for theories of cross-modal attention. The authors investigated why orienting attention to a visual event sometimes influences responses to subsequent sounds and why it sometimes fails to do so. They examined visual-cue-on-auditory-target effects in two paradigms--implicit spatial discrimination (ISD) and orthogonal cuing (OC)--that have yielded conflicting findings in the past. Consistent with previous research, visual cues facilitated responses to same-side auditory targets in the ISD paradigm but not in the OC paradigm. Furthermore, in the ISD paradigm, visual cues facilitated responses to auditory targets only when the targets were presented directly at the cued location, not when they appeared above or below the cued location. This pattern of results confirms recent claims that visual cues fail to influence responses to auditory targets in the OC paradigm because the targets fall outside the focus of attention. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cross-modal links in spatial attention

A great deal is now known about the effects of spatial attention within individual sensory modalities, especially for vision and audition. However, there has been little previous study of possible cross-modal links in attention. Here, we review recent findings from our own experiments on this topic, which reveal extensive spatial links between the modalities. An irrelevant but salient event presented within touch, audition, or vision, can attract covert spatial attention in the other modalities (with the one exception that visual events do not attract auditory attention when saccades are prevented). By shifting receptors in one modality relative to another, the spatial coordinates of these cross-modal interactions can be examined. For instance, when a hand is placed in a new position, stimulation of it now draws visual attention to a correspondingly different location, although some aspects of attention do not spatially remap in this way. Cross-modal links are also evident in voluntary shifts of attention. When a person strongly expects a target in one modality (e.g. audition) to appear in a particular location, their judgements improve at that location not only for the expected modality but also for other modalities (e.g. vision), even if events in the latter modality are somewhat more likely elsewhere. Finally, some of our experiments suggest that information from different sensory modalities may be integrated preattentively, to produce the multimodal internal spatial representations in which attention can be directed. Such preattentive cross-modal integration can, in some cases, produce helpful illusions that increase the efficiency of selective attention in complex scenes.     

Audiovisual links in endogenous covert spatial attention.

In 7 experiments we investigated cross-modal links for endogenous covert spatial orienting in hearing and vision. Participants judged the elevation (up vs. down) of auditory or visual targets regardless of their laterality or modality. When participants were informed that targets were more likely on 1 side, elevation judgments were faster on that side, even if the modality of the target was uncertain. When participants expected a target on a particular side in Just 1 modality, corresponding shifts of covert attention also took place in the other modality, as evidenced by faster elevation judgments on that side. However, it was possible to "split" auditory and visual attention when targets in the 2 modalities were expected on constant but opposite sides throughout a block, although covert orienting effects were larger when targets were expected on the same side in both modalities. These results show that although endogenous covert attention does not operate exclusively within a supramodal system, there are strong spatial links between auditory and visual attention. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Crossmodal links between vision and touch in covert endogenous spatial attention.

The authors report a series of 6 experiments investigating crossmodal links between vision and touch in covert endogenous spatial attention. When participants were informed that visual and tactile targets were more likely on one side than the other, speeded discrimination responses (continuous vs. pulsed, Experiments 1 and 2; or up vs. down, Experiment 3) for targets in both modalities were significantly faster on the expected side, even though target modality was entirely unpredictable. When participants expected a target on a particular side in just one modality, corresponding shifts of covert attention also took place in the other modality, as evidenced by faster elevation judgments on that side (Experiment 4). Larger attentional effects were found when directing visual and tactile attention to the same position rather than to different positions (Experiment 5). A final study with crossed hands revealed that these visuotactile links in spatial attention apply to common positions in external space. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effects of rotation on spatial attention

OBJECTIVE: To clarify whether out-of-hours health centre visits and referrals to hospital are equally distributed in the three different duty models being used for health care in southwestern Finland. DESIGN: A medical audit of 2926 health centre visits and 223 referrals to hospitals by general practitioners (GPs) on duty. The duty models were formed on the basis of a possibility to utilize a local health centre during nights and weekends. Two-month follow-up period. SETTING: Primary health care. Population 46438. MAIN OUTCOME MEASURES: Out-of-hours visits to health centres and referrals to hospital, and the effect of age and duty model on referrals and visits. RESULTS: Patients over 64 years of age received most of the referrals although they visited the health care centre less frequently than the 0-14 year-olds (p < 0.001). The people who had an opportunity to utilize their local health centres visited more during out-of-hours than those who did not have this opportunity (p < 0.001). CONCLUSIONS: The health centre visits were not equally distributed in the three examined duty models. The over 64 year-olds in particular had the least visits and the most referrals.     

Luminance and spatial attention effects on early visual processing

Event-related potentials (ERPs) were recorded from healthy subjects in response to unilaterally flashed high and low luminance bar stimuli presented randomly to left and right field locations. Their task was to covertly and selectively attend to either the left or right stimulus locations (separate blocks) in order to detect infrequent shorter target bars of either luminance. Independent of attention, higher stimulus luminance resulted in higher ERP amplitudes for the posterior N95 (80-110 ms), occipital P1 (110-140 ms), and parietal N1 (130-180 ms). Brighter stimuli also resulted in shorter peak latency for the occipital N1 component (135-220 ms); this effect was not observed for the N1 components over parietal, central or frontal regions. Significant attention-related amplitude modulations were obtained for the occipital P1, occipital, parietal and central N1, the occipital and parietal P2, and the parietal N2 components; these components were larger to stimuli at the attended location. In contrast to the relatively short latencies of both spatial attention and luminance effects, the first interaction between luminance and spatial attention effects was observed for the P3 component to the target stimuli (350-750 ms). This suggests that interactions of spatial attention and stimulus luminance previously reported for reaction time measures may not reflect the earliest stages of sensory/perceptual processing. Differences in the way in which luminance and attention affected the occipital P1, occipital N1 and parietal N1 components suggest dissociations among these ERPs in the mechanisms of visual and attentional processing they reflect.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of cross-modal and intramodal division of attention on perceptual implicit memory.

Extant results motivate 3 hypotheses on the role of attention in perceptual implicit memory. The first proposes that only intramodal manipulations of attention reduce perceptual priming. The second attributes reduced priming to the effects of distractor selection operating in a central bottleneck process. The third proposes that manipulations of attention only affect priming via disrupted stimulus identification. In Experiment 1, a standard cross-modal manipulation did not disrupt priming in perceptual identification. However, when study words and distractors were presented synchronously, cross-modal and intramodal distraction reduced priming. Increasing response frequency in the distractor task produced effects of attention regardless of target-distractor synchrony. These effects generalized to a different category of distractors arguing against domain-specific interference. The results support the distractor-selection hypothesis. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Figural aftereffects and spatial attention

Distracting attention away from the location of an adaptation figure reduces the positional shift of a displaced test figure in the figural aftereffect (FAE). Participants performed an alignment task after adaptation involving various manipulations of spatial attention. In 1 condition, participants counted how often numbers occurred in an alphanumeric sequence presented during adaptation. (The sequence also appeared in a comparison condition, but no attention was required.) The FAE was reduced when the alphanumeric sequence attended to was in the center of the display while the adaptation figure was 3 degrees eccentric but not when the pattern was superimposed on the adaptation figure. Forced attention to 1 feature of the adaptation figure, its orientation, did not reduce the FAE (Experiment 3). To obtain a maximum FAE, the span of attention must cover the adaptation figure.     

Dissociation of covert and overt spatial attention during prehension movements: selective interference effects

In four experiments, the influence of distractor objects on the temporal evolution of the reach-to-grasp movement toward a target object (an apple) was examined. In the first experiment, the distractor was another apple, which moved laterally behind the target and occasionally changed direction toward the target, thus becoming the to-be-grasped object. In the second and third experiments, the distractor was a stationary piece of fruit, which sometimes became the to-be-grasped object because of a change in illumination. The fourth experiment was a combination of the first two experiments. In all cases, selective interference effects on the transport and manipulation components were observed only when attention to the distractor was covert rather than overt. It is proposed that covert visuospatial attention selects information about distracting but potentially important stimuli, such that a registration of significance is accomplished without the need to process all available information.     

Size scaling and spatial factors in visual attention

This study investigates the effect of the visibility of near and far letter distractors on target processing by scaling the size of the distractor letters to compensate for changes in resolution across the visual field. In Experiment 1, scaled and unscaled distractors were presented at varied stimulus onset asynchronies. Results showed that scaling the size of distractor letters in relation to their distance from the target was effective in producing strong compatibility effects. Scaled distractors presented prior to, or simultaneously with, the target were found to interfere with target processing whether they were near or far from the target. Experiment 2 used scaled distractors and varied the presentation location and the amount of time for processing prior to the presentation of the target. Compatibility effects were found to vary by location and by the exposure duration of the distractor. The finding of distance effects at far locations supports a space-based visual-attention mechanism with a wide attention beam (Steinman, Steinman, & Lehmkuhle, 1995).     

The retinotopy of visual spatial attention

We used high-field (3T) functional magnetic resonance imaging (fMRI) to label cortical activity due to visual spatial attention, relative to flattened cortical maps of the retinotopy and visual areas from the same human subjects. In the main task, the visual stimulus remained constant, but covert visual spatial attention was varied in both location and load. In each of the extrastriate retinotopic areas, we found MR increases at the representations of the attended target. Similar but smaller increases were found in V1. Decreased MR levels were found in the same cortical locations when attention was directed at retinotopically different locations. In and surrounding area MT+, MR increases were lateralized but not otherwise retinotopic. At the representation of eccentricities central to that of the attended targets, prominent MR decreases occurred during spatial attention.     

Shifting and focusing auditory spatial attention.

Auditory spatial attention was investigated by manipulating spatial and temporal relations between an auditory spatial cue and an auditory target. The principal findings were that performance improved as time available to shift attention to a cued spatial position increased, accurate spatial cues facilitated performance more than inaccurate cues, performance was virtually identical for shifts of attention ranging from 0° and 180°, and performance declined as the distance of an unexpected target from a cued spatial location increased. The experiments provided evidence that auditory attention may be allocated to a specific location in response to an auditory spatial cue and that the time required to shift attention does not appear to depend on the distance of the shift. Furthermore, the findings suggest that the spatial distribution of auditory attention may be described most accurately by a gradient model in which attentional resources decline gradually with distance from a focal point. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Graded effects of spatial and featural attention on human area MT and associated motion processing areas

Functional magnetic resonance imaging was used to quantify the effects of changes in spatial and featural attention on brain activity in the middle temporal visual area and associated motion processing regions (hMT+) of normal human subjects. When subjects performed a discrimination task that directed their spatial attention to a peripherally presented annulus and their featural attention to the speed of points in the annulus, activity in hMT+ was maximal. If subjects were instead asked to discriminate the color of points in the annulus, the magnitude and volume of activation in hMT+ fell to 64 and 35%, respectively, of the previously observed maximum response. In another experiment, subjects were asked to direct their spatial attention away from the annulus toward the fixation point to detect a subtle change in luminance. The response magnitude and volume dropped to 40 and 9% of maximum. These experiments demonstrate that both spatial and featural attention modulate hMT+ and that their effects can work in concert to modulate cortical activity. The high degree of modulation by attention suggests that an understanding of the stimulus-driven properties of visual cortex needs to be complemented with an investigation of the effects of task-related factors on visual processing.     

Multiple resources in divided attention: A cross-modal test of the independence of hemispheric resources.

Used a dual-task methodology to assess a multiple-resources account of information processing in which each cerebral hemisphere is assumed to have access to its own finite amount of attentional resources. A visually presented verbal memory task was paired with an auditory tone memory task, and Ss, 19 right-handed male undergraduates, were paid to emphasize one task more than the other. When Ss were trying to remember tones presented to the right ear, they could trade performance between tasks as a function of the emphasis condition, whereas on left-ear trials they could not. A control session indicated that stimuli presented to the unattended ear demanded processing resources, even when it was to the detriment of performance. Data support the 2nd author and M. C. Polson's (see record 1982-07236-001) model of independence between the hemispheres' resource supplies. (27 ref) (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)     

Behavioral and computational models of spatial attention.

Pigeons pecked for food in a spatially cued choice reaction time (RT) task. A brief (50-msec) white light appeared on a left or right key and probabilistically predicted the location (on either the left or right key) of a subsequent target stimulus. The time between cue and target onset (stimulus onset asynchrony), the base rate of left cues, and the probability that the cue correctly predicted the target (cue validity) were experimentally varied. The mean RT to respond to the target key was faster on correctly cued trials (defining a validity effect), decreased for both valid and invalid trials as stimulus onset asynchrony increased (defining an alerting effect), showed a variety of base-rate effects, and did not depend on cue validity. It is shown with a computational-processing model that dynamic interactions of short-term and associative memory processes are sufficient to produce these attention-like empirical phenomena. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Semantic and spatial components of selective attention.

Semantic and spatial effects on selective processing were examined. A prime presented 250 ms or 1,000 ms before a pair of masked words was related to 1 of the words on 1/3 of the trials. Although Experiments 1 and 2 required report of both words, processing was selective; typically, just 1 word could be reported. In Experiment 1, reported words were more often top words, showing spatial selectivity, and more often words related to the prime, showing semantic selectivity. Experiment 2 included to-be-ignored peripheral cues 50 ms before the pair. Related words were reported more often at both delays, and cuing produced an additive benefit at 1,000 ms. Experiment 3 required report of just the cued word and included 100-ms cues. Cued words were reported more often, especially at 1,000 ms and with 100-ms cues, but semantic selectivity also occurred. Selectivity via semantic priming and via location reflect separate attentional mechanisms. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Some effects of testing methodology on children's cross-modal performance.

Tested 40 41-57 mo old children on the number of trials they took to learn the identical form-discrimination problem given in either visual or tactual modalities in either "held" (E gave S the reward) or "platform" (S himself picked up the reward) conditions. It appears that when testing methodology is equated in the 2 modalities, cross-modal transfer of a simple form discrimination is not asymmetrical, but rather is equivalent to the transfer from the tactual to the visual modality. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hemispheric asymmetries of near-far spatial attention.

Although most of the visual cognitive activities performed by the left hemisphere take place close to the body (peripersonal space), most visual cognitive activities mediated by the right hemisphere take place in extrapersonal space. The left hemisphere, therefore, may have a propensity to direct attention toward the body and the right hemisphere away from the body. Because attentional bias influences judgments of spatial magnitude, the authors tested this hypothesis. Normal participants were asked to compare the size of horizontal lines presented in the sagittal plane in either right or left hemispace. When participants looked leftward, lines appeared shorter than when participants looked rightward. These results are consistent with the hypothesis that the right hemisphere directs attention toward visual extrapersonal space and the left hemisphere directs attention toward visual peripersonal space. (PsycINFO Database Record (c) 2010 APA, all rights reserved)