A comparison of the effects of bilateral and unilateral infusions of muscimol into the basal forebrain on cued detection of visual targets in rats.

This study investigated the role of the basal forebrain cholinergic system (BFCS) in rats' performance of a visuospatial attention task. Muscimol was infused bilaterally and unilaterally into the BFCS to inhibit cholinergic projections to the cortex. Muscimol slowed responding without significantly affecting side-bias. Bilateral infusions increased accuracy for all targets, whereas unilateral infusions reduced accuracy for targets contralateral to the infusion and increased accuracy for targets ipsilateral to the infusion. After a low unilateral dose of muscimol, invalid cues impaired detection of contralateral targets and spared detection of ipsilateral targets. A high unilateral dose of muscimol impaired detection of contralateral targets independently of cueing. These results suggest that interhemispheric imbalance in cortical activity by pharmacological manipulation of the BFCS can impair the detection of lateralized visual stimuli. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Covert visual orienting across the lifespan.

Three groups of 20 K–5th graders, 20 college students, and 20 older adults (mean age 72.8 yrs) were tested. The S's task was the speeded discrimination of "X" from "O", but of primary interest was the effect of a location cue that appeared prior to the target. Both an abrupt stimulus cue and a voluntary information cue were studied using response time measures. Eye movements were monitored to control for differences in the ability to maintain fixation. Exp 1 showed that in comparison with young adults, children were less able to sustain orienting over time, and senior adults required more time to use the cue. Exp 2 (using K–1st graders, 4th–5th graders, 20 college students, and 20 older adults) tested the relation between stimulus and information cues when they both occurred prior to a given target. All age groups were able to use information cues in the presence of conflicting stimulus cues, but young adults were better able to do so than either children or senior adults. Results are interpreted as support for the view that separate mechanisms underlie stimulus-based versus information-based spatial orienting. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of superior colliculus lesions on rats' orienting and detection of neglected visual cues.

Superior colliculus lesions generally result in deficit in visual orienting described as sensory neglect. This observation was confirmed in this study: Rats with lesions did not orient to some stimuli that intact rats readily oriented to. However, rats with lesions did orient to stimuli that the intact rats treated as more salient. Also, when the less salient stimuli signaled aversive stimulation, the rats with lesions detected these stimuli. These findings suggest that superior colliculus lesions do not affect the detection of visual stimuli that have been neglected. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Development and habituation of the heart rate orienting response to auditory and visual stimuli in the rat.

Studied development and habituation of responsivity to sound and visual stimuli in 120 8–19 day old Sprague-Dawley pups by using a change in heart rate (HR) as the indicant response (Exp I). A change in HR to sound (white noise) first occurred around 14–25 days of age and was acceleratory in nature. Within 3 days, the direction of the HR response shifted to bradycardia. The HR response to light was also characterized by tachycardia in young pups (14 days), which shifted to bradycardia as the pups matured (16 days and older). In Exp II, the HR response of 15- and 19-day-old Ss was studied at 3 auditory stimulus intensities (60, 70, and 90 db, B scale). Stimulus intensity influenced the magnitude of the cardiac response in the 19-day-old pups. Data suggest that even weak sensory stimuli elicited a defensive reaction (HR acceleration) during the 1st few days that followed onset of function in each sensory system; later in development, the same stimulus elicited an orienting response (cardiac deceleration). (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of visual experience on the habituation of orienting behavior.

Three experiments studied the orienting behavior (OB) at 30, 60, 90, or 120 days old of male Long-Evans rats, of whom 88 were light-reared (LR) and 84 dark-reared (DR). OB was assessed by examining S's ability to interrupt ongoing licking and perform appropriate head and postural adjustments when presented with apparently moving or stationary light displays or tones. When the lights were first presented to the LR and DR Ss, their OB did not differ at any of the ages. However, age and visual experience did influence habituation and recovery of orienting with changes in the light display. The older DR Ss habituated with fewer repeated presentations of the light displays than the LR Ss and did not recover orienting as effectively to all the subsequent changes of the light displays. The younger LR and DR Ss did not differ reliably. Results are discussed with regard to the nature of the habituation process for rodents and the relation between visual experience and habituation of attentional responses. (32 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Object-based facilitation and inhibition from visual orienting in the human split-brain.

Object-based attention was examined in 2 split-brain patients. A precued object could move within a visual field or cross the midline to the opposite field. Normal individuals show an inhibition in detecting signals in the cued object whether it moves within or between fields. Both patients showed this effect when the cued object moved within a visual field. When it crossed the midline into the opposite visual field, however, detection was faster in the cued box. These results reveal both facilitatory and inhibitory effects on attention that are object based and may last for several hundred milliseconds. However, the inhibition requires an intact corpus callosum for interhemispheric transfer, whereas the facilitation is transferred subcortically. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Inhibitory component of externally controlled covert orienting in visual space.

Four experiments, with 24 university students and staff, investigated an inhibitory effect associated with externally controlled orienting, first identified by M. I. Posner and Y. A. Cohen (1980, 1984). The effect takes the form of an inability to respond quickly to a stimulus appearing in the same location in the visual periphery as a previous one that produced covert orienting. Several characteristics of the effect were revealed that eliminate possible explanations in terms of response inhibition, masking, and sensory habituation. Results show that the inhibitory component of orienting occurred whether or not the 1st stimulus required a response, lasted at least a second, affected not only the originally stimulated location but also nearby locations, was determined by environmental coordinates, and occurred both in the periphery and at the fovea. It is concluded that inhibition may act together with an early facilitatory component in directing the attention and eye movement systems to maintain efficient spatial sampling. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Chronometric analysis of apparent spotlight failure in endogenous visual orienting.

Ss made speeded responses to peripheral luminance increments or decrements preceded by informative central precues. In 4 experiments with 48 university students, one of these stimuli was much more likely to occur than the other. In a simple detection task, the likely and unlikely stimuli showed equivalent cuing effects. In a discrimination task (bright/dim), the likely stimuli showed cuing but the unlikely one did not (spotlight failure), and there was a tendency to make the likely response when the unlikely stimulus occurred at the cued location. In Exp 5, the 2 stimuli were equally likely, and a choice was required. Large cuing effects were observed for both stimuli with no evidence of a speed–accuracy trade-off. A logogen-activation framework is described within which criterion and sensitivity adjustments are needed to accommodate the full pattern of results. Endogenous orienting appears to enhance processing of all stimuli at attended (relative to unattended) locations, an effect that may be masked by specific stimulus or response expectancies. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attentional orienting within visual field in a lexical decision task.

The influence of spatial attention on lexical decisions to lateralized target letter-strings appearing either along with a distractor (Experiment 1) or in an otherwise empty field (Experiments 2–6) was examined. Attentional orienting was controlled by peripheral (Experiments 1, 2, 3, and 6) and central (Experiments 4–5) cuing methods. Manipulations of spatial attention, including cue validity and cue–target stimulus onset asynchrony, were combined with manipulations of word frequency in Experiments 3-6. All the attentional manipulations were effective, but they did not modify the right visual field advantage in word performance, In addition, the attentional effects did not interact with either the presence or absence of distractors or with stimulus familiarity. Implications of these results regarding the influence of spatial attention (the posterior attention system) on word processing are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Covert orienting biases in scene-based reference frames: Orientation priming and visual field differences.

Performance advantages for stimuli presented in the right versus the left visual field have been found in a variety of attentional tasks. Such advantages were exploited in the present set of studies to examine orientation priming and directional biases in retinotopic and scene-based spatial coordinates. The results demonstrate that directional biases occur within spatial coordinates across orientation transformations that dissociate retinotopic from scene-based visual half fields. The results are discussed concerning the representation of spatial maps in higher visual analysis, the role of spatial coordinates in guiding covert orienting, and methods of presenting stimuli in the right or left visual field to test for functional hemispheric asymmetries. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Parametric exploration of the Simon effect across visual space.

The Simon effect refers to the performance advantage for responding to the nonspatial identity of the target when the target's irrelevant location corresponds with the relative location of the response. The present study is a parametric examination of the magnitude of the Simon effect across visual space. Response keys were arranged along vertical, horizontal, and two diagonal axes, and stimuli were arranged in two concentric circles (near and far from fixation) along the same axes. The results show that the Simon effect is of similar magnitude regardless of stimulus-response axis. In contrast to findings from stimulus-response compatibility paradigms, there was no evidence in this study for the presence of an orthogonal compatibility effect or left-right prevalence effect, suggesting that these effects only arise when response location is relevant. The results demonstrate the robust generalizability of the Simon effect under different spatial conditions and thus broaden the relevance of the Simon effect to a variety of applications. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Asymmetries in visual search for conjunctive targets.

Asymmetry is demonstrated between conjunctive targets in visual search with no detectable asymmetries between the individual features that compose these targets. Exp 1 demonstrates this phenomenon for targets composed of color and shape. Exps 2 and 4 demonstrate this asymmetry for targets composed of size and orientation and for targets composed of contrast level and orientation, respectively. Exp 3 demonstrates that search rate of individual features cannot predict search rate for conjunctive targets. These results demonstrate the need for 2 levels of representations: one of features and one of conjunction of features. A model related to the modified feature integration theory is proposed to account for these results. The proposed model and other models of visual search are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Characteristics of covert and overt visual orienting: Evidence from attentional and oculomotor capture.

Five visual search experiments found oculomotor and attentional capture consistent with predictions of contingent orienting, contrary to claims that oculomotor capture is purely stimulus driven. Separate saccade and attend-only conditions contained a color target appearing either singly, with an onset or color distractor, or both. In singleton mode, onsets produced oculomotor and attentional capture. In feature mode, capture was absent or greatly reduced, providing evidence for top-down modulation of both types of capture. Although attentional capture by color abstractors was present throughout, oculomotor capture by color occurred only when accompanied by transient change, providing evidence for a dissociation between oculomotor and attentional capture. Oculomotor and attentional capture appear to be mediated by top-down attentional control settings, but transient change may be necessary for oculomotor capture. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Biases in visual orienting to negative and positive scenes in dysphoria: An eye movement study.

The study investigated biases for negative information in component processes of visual attention (initial shift vs. maintenance of gaze) in dysphoric and nondysphoric individuals. Eye movements were recorded while participants viewed a series of picture pairs depicting negative, positive, and neutral scenes (each pair presented for 3 s). Biases in initial orienting were assessed from the direction and latency of the initial shift in gaze, whereas biases in the maintenance of attention were assessed from the duration of gaze on the picture that was initially fixated. Results indicated that the dysphoric group showed a significantly greater bias to maintain gaze longer on negative pictures, relative to control pictures, compared with the nondysphoric group. There was no evidence of a dysphoria-related bias in initial shift of orienting to negative cues. Results are consistent with a depression-related bias that operates in the maintenance of attention on negative material. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Grouping processes in visual search: Effects with single- and combined-feature targets.

We report evidence for spatially parallel visual search for targets defined by combinations of form elements in visual search. In Section 1, we show that flat search functions occur for combined-form targets when distractor forms are homogeneous and can be grouped together, thus segmenting the target from the distractors. Introducing heterogeneous distractors lessens distractor grouping and can produce serial search. These results cannot be easily attributed to subjects' use of local feature information to discriminate targets. Instead, they suggest that grouping can operate at a level at which combined form information is represented. In Section 2 we show that these grouping effects are spatially scaled by the size of the stimuli. In Section 3 we show that heterogeneity does not prevent flat search functions when the target has a unique defining feature. Data are interpreted in terms of a hierarchical processing system involving both devoted single- and combined-feature (junction) maps. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Reflexive and voluntary orienting of visual attention: Time course of activation and resistance to interruption.

To study the mechanisms underlying covert orienting of attention in visual space, subjects were given advance cues indicating the probable locations of targets that they had to discriminate and localize. Direct peripheral cues (brightening of one of four boxes in peripheral vision) and symbolic central cues (an arrow at the fixation point indicating a probable peripheral box) were compared. Peripheral and central cues are believed to activate different reflexive and voluntary modes of orienting (J. Jonides, 1981; M. I. Posner; see record 1981-09397-001). Experiment 1 showed that the time courses of facilitation and inhibition from peripheral and central cues were characteristic and different. Experiment 2 showed that voluntary orienting in response to symbolic central cues is interrupted by reflexive orienting to random peripheral flashes. Experiment 3 showed that irrelevant peripheral flashes also compete with relevant peripheral cues. The amount of interference varied systematically with the interval between the onset of the relevant cue and of the distracting flash (cue-flash onset asynchrony) and with the cuing condition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The suppression of reflexive visual and auditory orienting when attention is otherwise engaged.

Two experiments were conducted to examine whether abrupt onsets are capable of reflexively capturing attention when they occur outside the current focus of spatial attention, as would be expected if exogenous orienting operates in a truly automatic fashion. The authors established a highly focused attentional state by means of the central presentation of a stream of visual or auditory characters, which participants sometimes had to monitor. No intramodal reflexive cuing effects were observed in either audition or vision when participants performed either an exogenous visual or auditory orthogonal cuing task together with the central focused attention task. These results suggest that reflexive unimodal orienting is not truly automatic. The fact that cuing effects were eliminated under both unimodal and cross-modal conditions is consistent with the view that auditory and visual reflexive spatial orienting are controlled by a common underlying neural substrate. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On the independence of naming and locating masked targets in visual search.

Twelve Ss were required to name or locate masked letters in arrays containing noise elements. Accuracy in locating was lower when target letters were presented among Vs than when presented among triangles or with no noise. Naming was as accurate when Vs and triangles were presented with the target as when no noise was presented. Since noise did not affect naming in the same way it affected locating, it was concluded that naming is independent of locating. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On the orienting value of attitudes: Attitude accessibility as a determinant of an object's attraction of visual attention.

Tested the hypothesis that objects toward which individuals hold attitudes that are highly accessible from memory (i.e., attitude-evoking objects) are more likely to attract attention when presented in a visual display than objects involving less accessible attitudes. In Exps 1 and 2, Ss were more likely to notice and report such attitude-evoking objects. Exp 3 yielded evidence of incidental attention; Ss noticed attitude-evoking objects even when the task made it beneficial to ignore the objects. Exp 4 demonstrated that inclusion of attitude-evoking objects as distractor items interfered with Ss' performance of a visual search task. Apparently, attitude-evoking stimuli attract attention automatically. Thus, accessible attitudes provide the functional benefit of orienting an individual's visual attention toward objects with potential hedonic consequences. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Species of redundancy in visual target detection.

We report a series of investigations into the effects of common names, physical identity, and physical similarity on visual detection time. The effect of these factors on the capacity of the system processing the signals was also examined. We used a redundant targets design with separate testing of the target-distractor (single target), target-target (redundant targets), and distractor-distractor (no targets) displays. When a target and a distractor share names, detection of the target is slower than it is in a situation in which the two do not go by a common name. Nevertheless, the gain reaped by redundant targets in this situation is larger and signal processing is of increased capacity compared with those in a situation in which the target and the distractor are coded by different names. The results also highlight the role of physical identity of targets: Detection is disproportionately efficient when reproductions of a given signal are presented. Together, the results provide guiding principles for a model of visual detection by a context-sensitive human detector. (PsycINFO Database Record (c) 2010 APA, all rights reserved)