Role Of Visual Attention Research Articles

The role of visual attention in action priming

It has been demonstrated that the task-irrelevant left-right orientation of an object is capable of facilitating left-right-hand responses when the object is orientated towards the responding hand. We investigated the role of attention in this orientation effect. Experiment 1 showed that object orientation facilitates responses of the hand that is compatible with the object's orientation, despite the entire object being irrelevant. However, when a task-relevant fixation point was displayed over the prime object in Experiment 2, the effect was not observed. Together Experiments 1 and 2 suggest that the orientation information of viewed objects primes the action selection processes even when the object is irrelevant, but only when attention is not allocated to a competing stimulus during the prime presentation. Experiment 3 suggested that the elimination of the effect in Experiment 2 could not be attributed to the elimination of an attentional shift to the graspable part of the prime. Finally, Experiment 4 showed that object orientation can evoke an abstract response code, influencing the selection of finger responses.

Do Visual Attentional Factors Contribute to Phonological Ability? Studies in Adult Dyslexia

A case study approach was taken to examine the role of visual attention and auditory memory processes in eight adults with dyslexia, all of whom demonstrated phonological difficulties. The participants were administered a battery of neuropsychological tests and participated in an attentional cueing experiment. Individual data revealed that, although one adult with dyslexia showed overt visual attention deficits on a visual search task, and five showed auditory working memory deficits, the difficulty that all of the adults with dyslexia had in common was with covert shifts of attention toward and away from fixation. These results indicate that deficits in overt visual attentional processing and working memory can be present with dyslexia, but neither is a necessary requirement. Overall, the results suggest that covert visual attention makes a significant contribution to phonological ability, which thus has implications for reading ability.

Parietal activation during visual search in the absence of multiple distractors.

Search for a target object embedded in a visual scene involves the posterior parietal cortex. This region is thought to play a role in visual attention by counteracting the effects of distractors on targets or by inhibiting distractors. Using fMRI, we investigated whether the parietal cortex is also engaged in visual search without distractors. Cortical activation was compared between two 'single object' search tasks differing only in difficulty. Activation differences between both tasks were found in the anterior and inferior part of the intraparietal sulcus, but in neither its posterior part nor the frontal eye fields. Thus a subset of parietal regions participates in the control of visual search even in the absence of distractors.

A dynamical model of figure‐ground reversal perception based on the role of visual attention

AbstractIn an attempt to clarify the dynamical process in human visual perception, we propose a neural network model explaining the figure‐ground reversal phenomenon of a three‐dimensional ambiguous figure, and examine its behavior in numerical experiments. In contrast to conventional models that explain perceptual reversal at a “symbolic representation level” using the oscillation between two memorized patterns in a network, our model tries to explain this phenomenon at a “structural representation level.” That is, the model has a field that represents the 3D structure of the visual input and the spatial distribution of visual attention, where the attention and structural representation interact with each other to bring dynamical change in the perceived structure. Another important feature of our model is that it reflects both space‐oriented and object‐oriented properties of visual attention. By discussing the structure and operation of our model, we introduce the concept of the “dynamics of perception and attention” as a general framework for understanding the dynamical transition of human visual perception. © 2002 Wiley Periodicals, Inc. Syst Comp Jpn, 33(10): 21–30, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10104

Visual Attention and Coactivation of Response Decisions for Features From Different Dimensions

The role of visual attention in task performance has been extensively debated. On the basis of the dimensional-action model, we hypothesized that a major role of attention is to transfer response decisions from targets on which it is focused to high-level centers dealing with response execution. This hypothesis predicts that response decisions for two targets will interact only when attention is focused on both targets, and only when the response to the targets is defined by different dimensions. Three experiments, using the redundancy-gain paradigm, tested and confirmed this prediction. Experiment 1 showed that coactivation of two cross-dimensional targets occurred only when the targets were positioned in the same location, not when they were in separate locations. Experiment 2 manipulated the focus of attention and showed that coactivation can occur even for targets positioned in different locations if they are both within the attentional focus. Experiment 3 showed that this attention-induced coactivation does not occur for targets from the same dimensional module. These results suggest that a major role of attention is postperceptual and involves gating of selected responses to executive functions.

Visual attention and coactivation of response decisions for features from different dimensions.

The role of visual attention in task performance has been extensively debated. On the basis of the dimensional-action model, we hypothesized that a major role of attention is to transfer response decisions from targets on which it is focused to high-level centers dealing with response execution. This hypothesis predicts that response decisions for two targets will interact only when attention is focused on both targets, and only when the response to the targets is defined by different dimensions. Three experiments, using the redundancy-gain paradigm, tested and confirmed this prediction. Experiment 1 showed that coactivation of two cross-dimensional targets occurred only when the targets were positioned in the same location, not when they were in separate locations. Experiment 2 manipulated the focus of attention and showed that coactivation can occur even for targets positioned in different locations if they are both within the attentional focus. Experiment 3 showed that this attention-induced coactivation does not occur for targets from the same dimensional module. These results suggest that a major role of attention is postperceptual and involves gating of selected responses to executive functions.

Role of Visual Attention in Cognitive Control of Oculomotor Readiness in Students with Reading Disabilities

This study investigated eye movement and comprehension therapy in Grade 6 children with reading disabilities (RD). Both order of therapy and type of therapy were examined. Furthermore, the implications of visual attention in ameliorating reading disability are discussed. Thirty-one students with RD were identified using standardized reading comprehension tests. Eye movements were analyzed objectively using an infra-red recording device. Reading scores of participating children were 0.5 to 1 SD below the national mean. Testing took place before the start of therapy (T1) and was repeated after 12 weeks (T2) and 24 weeks (T3) of therapy. One group of students had eye movement therapy first, followed by comprehension therapy; in the other group, the order was reversed. Data were evaluated using a repeated measures MANOVA and post hoc tests. At T1, mean reading grade was 2 years below grade level, and eye movement scores were at about Grade 2 level. Mean growth in reading comprehension for the total sample was 2.6 years (p < .01) at T3; equally significant improvement was measured in eye movements (p < .01). Learning rate in reading comprehension improved from 60% (T1) to 400% (T3). Although within-group differences were statistically significant, between-group differences were not significant for comprehension or eye movements. Order of therapy (comprehension first or eye movements first) was not significant. Improvements in within-group scores for comprehension and eye movements were consistently significant at T2 and T3. Eye movement therapy improved eye movements and also resulted in significant gains in reading comprehension. Comprehension therapy likewise produced improvement both in eye movement efficiency and in reading comprehension. The results support the notion of a cognitive link among visual attention, oculomotor readiness, and reading comprehension.

Associating object names with descriptions of shape that distinguish possible from impossible objects

Five experiments examine the proposal that object names are closely linked to representations of global, 3D shape by comparing memory for simple line drawings of structurally possible and impossible novel objects. Objects were rendered impossible through local edge violations to global coherence (cf. Schacter, Cooper, & Delaney, 1990) and supplementary observations confirmed that the sets of possible and impossible objects were matched for their distinctiveness. Employing a test of explicit recognition memory, Experiment 1 confirmed that the possible and impossible objects were equally memorable. Experiments 2–4 demonstrated that adults learn names (single-syllable non-words presented as count nouns, e.g., “This is a dax”) for possible objects more easily than for impossible objects, and an item-based analysis showed that this effect was unrelated to either the memorability or the distinctiveness of the individual objects. Experiment 3 indicated that the effects of object possibility on name learning were long term (spanning at least 2 months), implying that the cognitive processes being revealed can support the learning of object names in everyday life. Experiment 5 demonstrated that hearing someone else name an object at presentation improves recognition memory for possible objects, but not for impossible objects. Taken together, the results indicate that object names are closely linked to the descriptions of global, 3D shape that can be derived for structurally possible objects but not for structurally impossible objects. In addition, the results challenge the view that object decision and explicit recognition necessarily draw on separate memory systems, with only the former being supported by these descriptions of global object shape. It seems that recognition also can be supported by these descriptions, provided the original encoding conditions encourage their derivation. Hearing an object named at encoding appears to be just such a condition. These observations are discussed in relation to the effects of naming in other visual tasks, and to the role of visual attention in object identification.

Neurophysiological indices of voluntary and involuntary visual attention in humans

The visual evoked potentials (EPs) in response to lateralized and central visual symbols under the conditions of involuntary (passive viewing) and selective attention (when one of the symbols was a target and required a rapid and precise motor reaction) are considered. The evoked potentials in the occipital, parietal, and frontal derivations were recorded in 20 healthy subjects. It was shown that the EP during selective attention are most pronounced and more alike in the parietal derivations. A strong positive correlation was revealed between the EP amplitude ([N1–P3] component) and the EP stability (correlation between the repeated EP). The involuntary and voluntary forms of attention supplement each other: the more expressed the involuntary attention (assessed by the [N1–P3] component) the higher the EP to target stimuli during voluntary attention and the shorter the reaction time. It is suggested that the role of visual attention consists in the increase and stabilization of cortical activity (primarily, the parietal regions) engaged in solving a visual task.

Attention in the ventral pathway?

In real life, as opposed to laboratory experiments, multiple objects in the visual scene compete for attention, such that behaviourally relevant objects are processed at the expense of irrelevant objects. How this is achieved in terms of cortical activity is the topic of much current research, and the detailed map of visual areas in the macaque and their interconnections 1 Felleman D.J. Van Essen D.C. Distributed hierarchical processing in primate cerebral cortex. Cereb. Cortex. 1991; 1: 1-47 Crossref PubMed Scopus (5388) Google Scholar has aided greatly in the search for cortical regions that might have a role in visual attention. In a recent experiment, De Weerd and colleagues examined the possible role of two extrastriate visual areas, V4 and TEO, in attention 2 De Weerd P. et al. Loss of attentional stimulus selection after extrastriate cortical lesions in macaques. Nat. Neurosci. 1999; 2: 753-758 Crossref PubMed Scopus (132) Google Scholar . These two regions are part of the ‘ventral’ pathway through extrastriate cortex, which is important for object recognition in primates, although it has also been shown that responses of neurons in V4 and TEO are modulated by the attentional demands of many different visual task. De Weerd et al. tested directly the role of these areas in visual attention by making lesions in the cortex of two macaques, such that a lesion of V4 affected one quadrant of the visual field, a lesion of TEO affected another quadrant, with combined lesions of both areas affecting a third quadrant. The remaining quadrant was intact, thus serving as a control. The monkeys were trained on an orientation-discrimination task, and, in blocks of trials, were presented with grating stimuli away from the fixation point, in each of the visual quadrants in turn. In further blocks of trials, distractor discs surrounding the target grating were added to the visual display.

Maintaining Situational Awareness: The Role of Visual Attention

This study examined the relationship between the UFOV® test (Ball, et al. 1993), and measures of situational awareness (SA) for the purpose of identifying those components of visual attention that are most important in maintaining SA. Situational awareness was assessed using a PC based driving simulator that tests a participant's ability to detect and respond to hazardous situations, as well as their knowledge of the locations of other cars. Subtests 2 and 3 of the UFOV test, which assess a participants divided and selective attention ability, were found to be significantly correlated with a participant's ability to recognize hazards and recall the location of other cars. The results suggest that the divided and selective attention tasks of the UFOV® test measure abilities that contribute significantly to a person's capacity to maintain situational awareness.

Increasing the benefits of eye-tracking devices in divided visual field studies of cerebral asymmetry

A wide range of methods has been proposed for ensuring central fixation in divided visual field studies of cerebral asymmetry. We present some of the problems associated with ensuring central fixation and argue that objectively monitoring fixation location with an eye-tracking device can provide the only accurate and, therefore, acceptable technique. However, the mere use of this equipment does not overcome all of the problems associated with controlling fixation location, and previous studies have overlooked the importance of providing feedback on fixation accuracy and the role of visual attention. We propose a straightforward method of accommodating both these influences in studies using eyetracking devices to control fixation location.

Two Roles for Attention in Shape Perception: A Structural Description Model of Visual Scrutiny

This paper presents MetriCat, a model of the human capacity to recognize objects both as members of a general class (e.g. “chair”) and as specific instances (“my office chair”), and of the role of visual attention in this capacity. MetriCat represents the attributes of an object's parts and their relations in a non-linear fashion that provides a natural basis for recognition at both the class and instance levels (Stankiewicz & Hummel, 1996). Like previous structural description models (e.g. Hummel & Biederman, 1992), MetriCat represents part attributes and relations independently, dynamically binding them into structural descriptions. The resulting representation suggests two roles forvisual attention in shape recognition: attention for binding and attention for signal-to-noise control. MetriCat implements both functions as special cases of a single mechanism for controlling the synchrony relations among units representing separate object parts. The model accounts for the time course of class- and instance-level classification, and makes several predictions about the relationships between attention, time and levels of classification.

The role of attention in priming for left-right reflections of object images: Evidence for a dual representation of object shape.

Three experiments investigated the role of visual attention in priming for object images and their left-right reflections. Objects to which participants attended were visually primed in both the same view and in the left-right reflected view; ignored objects were primed only in the same view. The effects of attention (attended vs. ignored) and view (same vs. reflected) were strictly additive. These results suggest that 2 separate representations mediate human object recognition (J.E. Hummel & B.J. Stankiewicz, 1996): One requires attention but is invariant with left-right reflection, whereas the other can be activated automatically but is sensitive to left-right reflection. Both representations appear to be invariant with translation across the visual field.

A Polysynaptic Feedback Circuit in Rat Visual Cortex

Feedback connections from extrastriate cortex to primary visual cortex (V1) in the primate may provide "top-down" information that plays a role in visual attention and object recognition. Our work in a rodent model of corticocortical circuitry demonstrates that feedback pathways synapse preferentially with pyramidal cells in V1 () and favor excitation over inhibition in cortical microcircuits (). To investigate the polysynaptic circuits activated by feedback inputs, we studied chains of neurons postsynaptic to feedback connections using a combination of axonal tract tracing and anterograde degeneration. This approach enabled independent labeling of local collaterals of forward-projecting neurons in V1 and feedback connections from extrastriate lateromedial (LM) visual area to V1. Postsynaptic targets were identified in the electron microscope after retrograde transport of biotinylated dextran amine (BDA) to identify dendrites of forward-projecting neurons (i.e., from V1 to LM) and postembedding immunogold labeling to identify GABAergic interneurons. The results show that feedback connections provide strong monosynaptic input to forward-projecting neurons in V1. These neurons in turn make local connections that preferentially form synapses with other pyramidal cells ( approximately 97%), many of which were identified as forward-projecting neurons. This indicates that feedback pathways provide input directly to neurons which make the reciprocal forward connection, and that feedback-recipient forward-projecting neurons are strongly interconnected. The function of these excitatory networks within V1 may be to amplify feedback activity and provide a circuit for modulation of striate cortical activity by top-down influences.

The Role of Visual Attention in Head-Up Displays: Design Implications for Varying Symbology Intensity

Twenty pilots from the University of Illinois flew a low fidelity simulator during cruise flight. The intensity of the display symbology was manipulated in three different weather conditions to influence the discriminability of the instrumentation. The symbology was displayed in either head-up or head-down locations, with equivalent optical distances and display formats. Half of the subjects flew with a conformal symbology set, while the other half flew with a partially conformal symbology set. Responses to near and far domain events were measured, and tracking error of the three axes of control was calculated. The results revealed a head-up advantage to the far domain event detection and a head-down advantage to the near domain event detection. Performance in the head-up condition approached that of the otherwise superior head-down condition when an appreciable contrast between the symbology and the background environment was provided. The results are discussed in terms of an effect of the modulation of focused attention.

The role of visual attention in saccadic eye movements.

The relationship between saccadic eye movements and covert orienting or visual spatial attention was investigated in two experiments. In the first experiment, subjects were required to make a saccade to a specified location while also detecting a visual target presented just prior to the eye movement. Detection accuracy was highest when the location of the target coincided with the location of the saccade, suggesting that subjects use spatial attention in the programming and/or execution of saccadic eye movements. In the second experiment, subjects were explicitly directed to attend to a particular location and to make a saccade to the same location or to a different one. Superior target detection occurred at the saccade location regardless of attention instructions. This finding shows that subjects cannot move their eyes to one location and attend to a different one. The result of these experiments suggest that visuospatial attention is an important mechanism in generating voluntary saccadic eye movements.

The role of visual attention in neglect: A dissociation between perceptual and directional motor neglect

Abstract Patients with unilateral spatial neglect (neglect, for short) fail to report, respond, or orient to stimuli presented on the side of space contralateral to the lesion. This dysfunction is evident when the task requires an overt response. In contrast, patients can process the neglected stimuli and perform post-perceptual processing of the neglected stimuli, when the task requires a covert response (Berti & Rizzolatti, 1992; Lìdavas, Paladini, & Cubelli, 1993).

Electroretinograms reveal no evidence for centrifugal modulation of retinal inputs during selective attention in man.

ABSTRACTEason, Oakley, and Flowers (1983, Physiological Psychology, 11, 18–28) have recently described changes in the B‐wave and after‐potential of the human electroretinogram (ERG) during spatial selective attention. These results suggested that centrifugal modulation of retinal input may play a role in visual attention. We investigated this effect in two experiments in which subjects attended to sequences of flashes in one visual half‐field while ignoring similar flashes in the opposite half‐field. Visual event‐related potentials (ERPs) were recorded from electrodes placed at periorbital and scalp sites, while the ERG was simultaneously recorded using a gold‐foil electrode contacting the cornealscleral surface of the right eye. Selective visual attention was evident in an enhancement of the scalp‐recorded N150 component of the visual ERP to flashes in the attended half‐field. However, no effect of attention was observed on the B‐wave or after‐potential of the ERG. Long‐latency positive shifts related to attention were demonstrated in the corneal‐scleral recording and are discussed with respect to volume‐conducted brain activity.

Delayed response deficits in squirrel monkeys with unilateral lesions in the midbrain reticular formation

Electrophysiological experiments suggest that the midbrain reticular formation plays a role in visual attention. However, behavioral tests of this hypothesis have been few and their results inconsistent. Squirrel monkeys with unilateral lesions in the midbrain reticular formation were compared to control animals in their performance on a delayed-response task and a visual pattern discrimination. Nystagmus, adduction of limbs, and lack of visual responsivity were noted a few days after the lesion was made, but these symptoms were transient and were not seen during delayed response testing. The monkeys with lesions had delayed response deficits when the baited food well was contralateral to the lesion and responses were delayed 10 sec or longer. They did not differ significantly from controls on the delayed response task when the baited food well was ipsilateral to the lesion or in learning the visual pattern discrimination. The delayed response task presumably measures the ability to maintain orienting responses, overtly or covertly, during the delay interval. This experiment suggests that the midbrain reticular formation facilitates orienting responses over long delays.